
==== Front
Mol Biol Rep
Mol Biol Rep
Molecular Biology Reports
0301-4851
1573-4978
Springer Netherlands Dordrecht

39287911
9930
10.1007/s11033-024-09930-7
Original Article
Intervertebral disc degenerative disease in South Africa: a case-control analysis of selected gene variants
Pearce Keenau kpearce@uwc.ac.za

1
Less Stephanie 1
Liebenberg Adriaan W. 2
Benjeddou Mongi 1
1 https://ror.org/00h2vm590 grid.8974.2 0000 0001 2156 8226 Precision Medicine Unit, Department of Biotechnology, University of the Western Cape, Cape Town, South Africa
2 Health Collective, Panorama Healthcare Building, Cape Town, South Africa
17 9 2024
17 9 2024
2024
51 1 9929 4 2024
10 9 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by/4.0/ Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Background

Intervertebral disc (IVD) degenerative disease is a multifactorial disease for which genetics plays an integral role. Several genes, and their variants, associated with the development and progression of IVD degenerative disease have been identified. While several studies have investigated these genes in Asian and European populations, no available evidence exists for the South African population. Therefore, this study aimed to investigate these parameters.

Methods and results

Biological samples were collected in the form of buccal swabs from patients and DNA was extracted using a standard salt-lysis protocol. DNA purity and quantity was assessed by spectrophotometry, and subsequent genotyping was performed using the MassARRAY®System IPLEX extension reaction. For associations between variants and the presence of IVD degenerative disease, odds ratios (OR), confidence intervals (CI), chi-squared analysis and logistic regression was calculated. Age and sex were adjusted for, and Bonferroni’s correction was applied. This study found statistically significant associations for five of the evaluated single nucleotide polymorphisms (SNPs) with IVD degenerative disease, whereby IL-1α rs1304037 and rs1800587, ADAMTs-5 rs162509, and MMP-3 rs632478 demonstrated increased odds of a positive diagnosis for IVD degenerative disease, while decreased odds of IVD degenerative disease were seen for GDF-5 rs143383.

Conclusion

To the best of our knowledge, this study represents the first of its kind to investigate the association of gene variants associated with IVD degenerative disease within the South African population. This study has shown that 5 of these gene variants were significantly associated with the presence of IVD degenerative disease, reflecting their integral roles in development and possible progression of the disease.

Keywords

Intervertebral disc degenerative disease
Single nucleotide polymorphism
Genotype
Allele
South Africa
University of the Western CapeOpen access funding provided by University of the Western Cape.

issue-copyright-statement© Springer Nature B.V. 2024
==== Body
pmcIntroduction

Intervertebral disc (IVD) degenerative disease and related back pain are either acute or chronic forms of disease that may be caused by various factors [1, 2]. Globally, these conditions represent a significant cause of diminished quality of life, morbidity, and mortality. Lower back pain (LBP), in particular, is a common debilitating musculoskeletal condition and affects approximately 637 million people, globally–with a lifetime prevalence of approximately 80% [2–4]. In South Africa, the prevalence of diagnosed spinal degenerative disease in the urban population is estimated to range from 48 to 78.2% [5]. Many causes for LBP exist, but IVD degeneration has been found to be a more common diagnosis among individuals who suffer from LBP than those who do not. Back pain may not always be a symptom of IVD degeneration, although it is often an early sign of degenerative spine pathologies. The IVD is among the most pivotal biological structures of the human body [6, 7].

Progressive degradation of IVD structures that leads to disruption of the homeostasis of the spine is clinically known as IVD degeneration and is often associated with severe pain [7]. IVDs are composed of fibrocartilaginous tissue that assists in maintaining stability and flexibility of the entire spine [8]. The primary role of the IVD is to connect two adjacent vertebral bodies while acting as a cushion that carries weight and pressure attributed to mechanical load. An intact and healthy IVD is comprised of three main structures: the central nucleus pulposus, the external annulus fibrosus, and endplates [9]. These structures provide the IVD with high compressive and tensile strength, support axial compression of the spine, and allow multiaxial flexibility [10].

IVD degenerative disease is a multifactorial disease often emerging due to several factors causing tissue weakening which ultimately results in pathological changes in the IVD—particularly the production of inflammatory mediators, increased apoptosis, and extracellular matrix loss [10]. These include endplate damage, nutritional deficiency, abnormal load, smoking, ageing, and genetics [10]. Genetic factors in particular have been estimated to contribute an estimated 75% to IVD degenerative disease aetiology [11, 12]. Genetic variation associated with the genes involved in processes that are related to degradation of the extracellular matrix components, apoptosis, and inflammation, have been associated with structural and functional changes within the IVD, which leads to disruption of the IVD’s metabolic activities and mechanical properties [8].

To date, several genes, and their variants, associated with the development and progression of IVD degenerative disease have been identified, including COL1A1 and COL11A1, GDF-5, CASP-3 and CASP-9, IL-1α and IL-6, ADAMTS-5, KIAA, CILP, COMT, MMP-3, and MMP-6 [7, 8, 13, 14]. Notably, associated gene variants have been extensively investigated in Asian and European populations, for which risk genotypes and alleles have been identified. It is essential to note, however, that South Africa is home to several genetically diverse population groups representing unique genetic profiles which include novel and rare variants regarding pharmaco-genetically relevant genes [15–17]. Moreover, this genomic diversity is a largely understudied domain, as compared to European populations, and within the context of IVD degenerative diseases is non-existent in the available literature. It is therefore unclear how previously identified genetic associations to IVD degenerative disease relate to the South African population and the unique genetic diversity represented therein. Therefore, this study aimed to investigate selected gene variants with the greatest level of evidence for association with IVD degenerative disease within the South African population.

Materials and methods

Patient data collection

All participants were briefed about the project and a consent form was completed and submitted by each participant before the experiment was conducted. All clinical data was collected by the Health Collective personnel in accordance with the Helsinki Declaration of 1975, as revised in 2016, and the Protection of Personal Information Act (POPIA) of 2013, and deidentified prior to inclusion in this study [18–20]. Ethical clearance for this study was obtained from the Senate Research Committee of the University of the Western Cape [Ethics clearance number BM 22/4/7].

Biological Sample collection

Biological samples were collected in the form of buccal swabs from patients visiting the Health Collective, Panorama Healthcare Building, Cape Town, South Africa. All patients included in this study were confirmed to have IVD degenerative disease by magnetic resonance imaging (MRI) and/or radionuclide scans and were confirmed to not have evidence of active cancer(s), a record of spinal trauma, or trauma to the surrounding spinal structures. Convenience sampling was employed for samples collected from healthy volunteers. An ethnically mixed population was utilised for the study cohort, and ethnicities of participants were determined by self-report.

Single nucleotide polymorphism selection

The 20 relevant genetic variants selected for this study were chosen based upon previous publications, where association was made between single nucleotide polymorphisms (SNPs) and the presence of IVD degenerative disease. The Ensembl data-base, accessed on 17 June 2023, was also used for cross-referencing the selected SNPs (http://www.ensembl.org) [21].

DNA isolation and genotyping

Genomic DNA was isolated from buccal swabs using a standard salt-lysis protocol [22]. Samples were stored at − 20 °C. DNA was quantified using a NanoDrop™2000/ 2000c UV/VIS Spectrophotometer (Thermo Scientific, Waltham, MA, USA). The SNPs were genotyped using the MassARRAY®System IPLEX extension reaction (Agena Bioscience, San Diego, CA, USA). Genotypes of the selected SNP variants were determined for all the study participants (Tables 3 and 4).

Statistical analysis

Statistical tests were selected in accordance with Clark et al. (2011) and included Hardy-Weinberg equilibrium (HWE) to assess the expected and observed genotypic distribution within the study population, odds ratio (OR) as a measure of association between variants and IVD degeneration, and logistic regression to adjust for age and sex [23]. Finally, Bonferroni’s correction was employed to control for error [23]. Statistical analysis for HWE, genotype frequencies, and allele frequencies were performed using GenALEx version 6.5 [24, 25]. For HWE, P < 0.05 was considered significant and thus a departure from HWE. For associations between variants and IVD degenerative disease, ORs with 95% confidence intervals, and logistic regression was calculated using IBM Statistical Package for Social Sciences (SPSS) version 26. A significance threshold of 0.05 was employed for association studies.

Results

Demographics and covariates

Study population demographic data are shown in Table 1, and age sex and smoking were evaluated as possible covariates. Following analysis, only age (P = 0.0056) and sex, i.e. female (P = 0.0019), were determined to be covariates within the study population (Table 1). The identified covariates were subsequently utilised in logistic regression.

Genotype distribution and hardy-Weinberg equilibrium

Genotype and allele distribution of the 20 SNPs were determined in the study participants (Tables 3 and 4). All SNPs analysed within the study population were found to be within Hardy-Weinberg equilibrium (HWE), with p-values ranging between 0.1007 and 0.9835 (Table 2).

Association of SNPs with IVD degenerative disease

Among the SNPs selected for this study, five displayed a significant association between IVD degenerative disease and genotype or allele prior to adjustment (Table 4). All non-significant SNPs are displayed in Table 3. The five significantly associated genes/SNPs are: IL-1α rs1304037 and rs1800587, GDF-5 rs143383, ADAMTS-5 rs162509, and MMP-3 rs632478.

Prior to adjustment, the heterozygous genotype CT, and the minor allele C of rs1304037 demonstrated significant associations with diagnosis of IVD degenerative disease [P = 0.0456, (OR: 2.22, 95% CI: 1.01–4.91) and P = 0.0476 (OR:1.77, 95% CI: 1.00-3.15) respectively] (Table 4). For rs1800587, the heterozygous genotype GA, and the minor allele A demonstrated significant associations with diagnosis of IVD degenerative disease [P = 0.0249, (OR: 2.50, 95% CI: 1.11–5.62) and P = 0.0434 (OR:1.78, 95% CI: 1.01–3.14) respectively] (Table 4). When analysed, the heterozygous genotype GA, and the minor allele A of rs143383 demonstrated significant associations with diagnosis of IVD degenerative disease [P = 0.0299, (OR: 0.37, 95% CI: 0.15–0.90) and P = 0.0474 (OR:0.58, 95% CI: 0.34–0.99) respectively] (Table 4). Next, the homozygous minor genotype CC and the minor allele C of rs162509 demonstrated significant associations with diagnosis of IVD degenerative disease [P = 0.0152, (OR: 3.71, 95% CI: 1.29–10.68) and P = 0.0112 (OR: 1.99, 95% CI: 1.16–3.40) respectively] (Table 4). Finally, the heterozygous genotype GT of rs632478 demonstrated significant associations with diagnosis of IVD degenerative disease [P = 0.0249, (OR: 2.70, 95% CI: 1.13–6.44)] (Table 4).

Following adjustment, only the C allele of rs1304037 remained significantly associated [P = 0.0459 (OR:1.99, 95% CI: 1.01–3.93) respectively] (Table 4). For rs1800587, the heterozygous genotype GA, and the minor allele A remained significantly associated following adjustment [P = 0.0249, (OR: 2.55, 95% CI: 1.00-6.49) and P = 0.0434 (OR:2.14 95% CI: 1.10–4.18) respectively] (Table 4). The homozygous minor genotype CC and the minor allele C of rs162509 remained significantly associated with IVD degenerative disease following adjustment [P = 0.0105, (OR: 6.47, 95% CI: 1.54–27.07) and P = 0.0040 (OR: 2.59, 95% CI: 1.35–4.96) respectively] (Table 4). Once adjusted, only the heterozygous genotype i.e. GT of rs632478 demonstrated a significant association with diagnosis of IVD degenerative disease [P = 0.0057, (OR: 5.17, 95% CI: 1.61–16.61) (Table 4).

Lastly, after Bonferroni correction, significance was maintained for the A allele of rs1800587 (P = 0.0498), the homozygous minor genotype CC, and the minor allele C of rs162509 (P = 0.0210 and P = 0.0080), along with the heterozygous GT genotype of rs632478 (P = 0.0114) (Table 4).

Table 1 Study population demographic data demonstrating the average age, sex and smoking status within the study population, along with significant associations for age and sex (female) with IVD degeneration

Parameter		Total patients (n = 117)	Diagnosed IVD degenerative disease
(n = 67)	No IVD degenerative disease
(n = 50)	p-value	
Age (years; mean ± SD)	Combined	50.5 ± 18.6	58.9 ± 13.2	39.2 ± 19.0	P = 0.0056	
Sex	Male

Female

	47

70

	23

44

	24

26

	P = 0.1390

P = 0.0019

	
Smoking		37	15	22	P = 0.2498	
Significance (p < 0.05) is shown in bold

Table 2 SNP information including rsID numbers, gene name, chromosomal position, location, and allelic change, all evaluated SNPs were within HWE

SNP	Gene	Chromosomal position	Location	Allele change	HWE p-value	
rs1052576	CASP-9	1:15506048	Missense	C > T	0.9260	
rs1304037	IL-1α	2:112774659	3’ UTR	T > C	0.6098	
rs1420100	IL-18	2:102420542	Intron	A > C	0.2543	
rs143383	GDF-5	20:35438203	5’ UTR	G > A	0.9010	
rs162509	ADAMTS-5	21:26953456	Intron	G > C	0.3239	
rs1676486	COL11A1	1:102888582	Missense	G > A	0.1379	
rs16924573	KIAA1217	10:24315964	Intron	G > A	0.6592	
rs16944	IL-1β	2:112837290	Intergenic	A > G	0.1048	
rs17561	IL-1α	2:112779646	Missense	C > A	0.9750	
rs17576	MMP-9	20:46011586	Missense	A > G	0.9835	
rs1800012	COL1A1	17:50200388	Intron	C > A	0.3443	
rs1800587	IL-1α	2:112785383	Intergenic	G > A	0.7842	
rs1800795	IL-6	7:22727026	Intron	G > C	0.2240	
rs20575	DR4	8:23201811	Missense	G > C	0.3416	
rs2073711	CILP	15:65201874	Missense	A > G	0.2693	
rs2076311	COL11A2	6:33177592	Intron	C > A	0.8490	
rs2228564	COL9A2	1:40307477	Missense	C > T	0.1320	
rs2856836	IL-1α	2:112774506	3’ UTR	A > G	0.7926	
rs4633	COMT	22:19962712	Synonymous	C > T	0.1007	
rs632478	MMP-3	11:102844950	Intergenic	G > T	0.1721	
Significance (p < 0.05) is shown in bold

Table 3 Genotype and allele frequencies of 20 SNPs demonstrating no significant association to IVD degenerative disease for 15 SNPs

SNP	Genotype/
Allele	Case
n (%)	Control
n (%)	OR (95% CI)	p-value	
rs1052576	CC	29 (43.9)	13 (27)	Reference		
CT	27 (40.9)	27 (56.2)	2.23 (0.96–5.19)	P = 0.0625	
TT	10 (15.1)	8 (16.6)	1.78 (0.57–5.56)	P = 0.3180	
C	85 (64.4)	53 (55.2)	Reference		
T	47 (35.6)	43 (44.8)	1.46 (0.86–2.51)	P = 0.1620	
rs1420100	AA	14 (21.2)	13 (26.5)	Reference		
AC	29 (43.9)	22 (44.8)	0.81 (0.32–2.08)	P = 0.6722	
CC	23 (34.8)	14 (28.5)	0.66 (0.24–1.79)	P = 0.4104	
A	57 (43.1)	48 (48.9)	Reference		
C	75 (56.8)	50 (51)	0.78 (0.46–1.33)	P = 0.3830	
rs1676486	GG	40 (61.5)	29 (61.7)	Reference		
GA	24 (36.9)	17 (36.1)	0.98 (0.45–2.14)	P = 0.9536	
AA	1 (1.5)	1 (2.1)	1.38 (0.08–22.97)	P = 0.8227	
G	104 (80)	75 (79.7)	Reference		
A	26 (20)	19 (20.2)	1.01 (0.52–1.96)	P = 0.9687	
rs16924573	GG	61 (93.8)	43 (89.5)	Reference		
AG	4 (6.1)	5 (10.4)	1.77 (0.45–6.99)	P = 0.4130	
G	126 (96.9)	91 (94.7)	Reference		
A	4 (3)	5 (5.2)	1.73 (0.45–6.62)	P = 0.4231	
rs16944	AA	13 (19.6)	11 (22.9)	Reference		
GA	25 (37.8)	22 (45.8)	1.04 (0.39–2.79)	P = 0.9379	
GG	28 (42.4)	15 (31.2)	0.63 (0.23–1.75)	P = 0.3792	
A	51 (38.6)	44 (45.8)	Reference		
G	81 (61.3)	52 (54.1)	0.74 (0.43–1.26)	P = 0.2770	
rs17561	CC	40 (61.5)	24 (50)	Reference		
CA	22 (33.8)	20 (41.6)	1.51 (0.69–3.34)	P = 0.3021	
AA	3 (4.6)	4 (8.3)	2.22 (0.46–10.79)	P = 0.3220	
C	102 (78.4)	68 (70.8)	Reference		
A	28 (21.5)	28 (29.1)	1.5 (0.81–2.75)	P = 0.1905	
rs17576	AA	17 (26.1)	14 (28.5)	Reference		
AG	32 (49.2)	25 (51)	0.95 (0.39–2.29)	P = 0.9065	
GG	16 (24.6)	10 (20)	0.76 (0.26–2.19)	P = 0.6102	
A	66 (50.7)	53 (54)	Reference		
G	64 (49.2)	45 (45.9)	0.87 (0.51–1.48)	P = 0.6202	
rs1800012	CC	43 (70.4)	36 (75)	Reference		
CA	17 (27.8)	12 (25)	0.84 (0.36–1.99)	P = 0.6979	
AA	1 (1.6)	0 (0)	0.39 (0.02–10.05)	P = 0.5754	
C	103 (84.4)	84 (87.5)	Reference		
A	19 (15.5)	12 (12.5)	0.74 (0.35–1.68)	P = 0.5196	
rs1800795	GG	32 (48.4)	31 (64.5)	Reference		
CG	28 (42.4)	12 (25)	0.44 (0.19–1.02)	P = 0.0563	
CC	6 (9)	5 (10.4)	0.86 (0.24–3.11)	P = 0.8184	
G	92 (69.6)	74 (77)	Reference		
C	40 (30.3)	22 (22.9)	0.68 (0.37–1.25)	P = 0.2171	
rs20575	GG	12 (18.1)	16 (33.3)	Reference		
GC	39 (59)	23 (47.9)	0.44 (0.18–1.09)	P = 0.0785	
CC	15 (22.7)	9 (18.7)	0.45 (0.15–1.37)	P = 0.1604	
G	63 (47.7)	55 (57.2)	Reference		
C	69 (52.2)	41 (42.7)	0.68 (0.40–1.15)	P = 0.1543	
rs2073711	AA	14 (22.2)	9 (18.3)	Reference		
AG	28 (44.4)	21 (42.8)	1.17 (0.42–3.20)	P = 0.7650	
GG	21 (33.3)	19 (38.7)	1.40 (0.49–3.99)	P = 0.5205	
A	56 (44.4)	39 (39.7)	Reference		
G	70 (55.5)	59 (60.2)	1.21 (0.70–2.06)	P = 0.4851	
rs2076311	CC	24 (38.7)	24 (48.9)	Reference		
CA	29 (46.7)	21 (42.8)	0.72 (0.32–1.60)	P = 0.4274	
AA	9 (14.5)	4 (8.1)	0.44 (0.12–1.64)	P = 0.2238	
C	77 (62.1)	69 (70.4)	Reference		
A	47 (37.9)	29 (29.5)	0.68 (0.39–1.21)	P = 0.1959	
rs2228564	CC	9 (13.8)	3 (6.2)	Reference		
CT	20 (30.7)	19 (39.5)	2.85 (0.66–12.15)	P = 0.1568	
TT	36 (55.3)	26 (54.1)	2.17 (0.53–8.79)	P = 0.2793	
C	38 (29.2)	25 (26)	Reference		
T	92 (70.7)	71 (73.9)	1.17 (0.64–2.12)	P = 0.5973	
rs2856836	AA	40 (61.5)	24 (51)	Reference		
GA	22 (33.8)	20 (42.5)	1.52 (0.69–3.34)	P = 0.3021	
GG	3 (4.6)	3 (6.3)	1.67 (0.31–8.93)	P = 0.5508	
A	102 (78.4)	68 (72.3)	Reference		
G	28 (21.5)	26 (27.6)	1.39 (0.75–2.57)	P = 0.2915	
rs4633	CC	21 (32.3)	16 (32.6)	Reference		
CT	25 (38.4)	23 (46.9)	1.21 (0.51–2.86)	P = 0.6683	
TT	19 (29.2)	10 (20.4)	0.69 (0.25–1.89)	P = 0.4705	
C	67 (51.5)	55 (56.1)	Reference		
T	63 (48.4)	43 (43.8)	0.83 (0.49–1.40)	P = 0.4922	
OR: odds ratio; CI 95% confidence interval. Percent does not account of missing alleles at specific loci.

Table 4 Genotype and allele frequencies of 5 SNPs demonstrating significant association to IVD degenerative disease adjusted for age and sex

	Unadjusted	Adjusted	
SNP/ Gene	Genotype
/Allele	Case
n (%)	Control
n (%)	OR (95% CI)	p-value	OR (95% CI)	p-value	Bonferroni corrected p-values	
rs1304037	TT	37 (57.8)	18 (36.7)	Reference		Reference			
IL-1α	CT	24 (37.5)	26 (53)	2.22 (1.01–4.91)	P = 0.0456	2.29 (0.91–5.75)	P = 0.0773	-	
CC	4 (6.2)	5 (10.2)	2.56 (0.61–10.74)	P = 0.1857	3.36(0.64–17.44)	P = 0.1491	-	
T	98 (75.3)	62 (63.2)	Reference		Reference			
C	32 (24.6)	36 (36.7)	1.77 (1.00-3.15)	P = 0.0476	1.99 (1.01–3.93)	P = 0.0459	P = 0.0918	
rs1800587	GG	36 (56.9)	17 (34.6)	Reference		Reference			
IL-1α	GA	22 (33.8)	26 (53)	2.50 (1.11–5.62)	P = 0.0249	2.55 (1.00-6.49)	P = 0.0488	P = 0.0976	
AA	6 (9)	6 (12.2)	2.11 (0.59–7.54)	P = 0.2409	3.50 (0.76–16.01)	P = 0.1063	-	
G	96 (73.8)	60 (61.2)	Reference		Reference			
A	34 (26.1)	38 (38.7)	1.78 (1.01–3.14)	P = 0.0434	2.14 (1.10–4.18)	P = 0.0249	P = 0.0498	
rs143383	GG	12 (18.7)	19 (38.7)	Reference		Reference			
GDF-5	GA	36 (56.2)	21 (42.8)	0.37 (0.15–0.90)	P = 0.0299	0.29 (0.08–1.01)	P = 0.0529	-	
AA	16 (25)	9 (18.3)	0.36 (0.12–1.06)	P = 0.0629	0.178 (0.02–1.13)	P = 0.0673	-	
G	60 (46.8)	59 (60.2)	Reference		Reference			
A	68 (53.1)	39 (39.7)	0.58 (0.34–0.99)	P = 0.0474	0.535 (0.28-1.00)	P = 0.0516	-	
rs162509	GG	24 (37.5)	11 (22.4)	Reference		Reference			
ADAMTS-5	CG	30 (46.8)	21 (42.8)	1.53 (0.62–3.79)	P = 0.3594	2.36 (0.72–7.71)	P = 0.1539	-	
CC	10 (15.6)	17 (34.6)	3.71 (1.29–10.68)	P = 0.0152	6.47 (1.54–27.07)	P = 0.0105	P = 0.0210	
G	78 (60.9)	43 (43.8)	Reference		Reference			
C	50 (39)	55 (56.1)	1.99 (1.16–3.40)	P = 0.0112	2.59 (1.35–4.96)	P = 0.0040	P = 0.0080	
rs632478	GG	25 (42.6)	10 (22)	Reference		Reference			
MMP-3	GT	28 (45.9)	32 (64)	2.70 (1.13–6.44)	P = 0.0249	5.17 (1.61–16.61)	P = 0.0057	P = 0.0114	
TT	7 (11.4)	7 (14)	2.36 (0.67–8.36)	P = 0.1818	2.87 (0.66–12.52)	P = 0.1585	-	
G	80 (65.5)	54 (54)	Reference		Reference			
T	42 (34.4)	46 (46)	1.62 (0.94–2.79)	P = 0.0803	1.81 (0.94–3.49)	P = 0.0740	-	
OR: odds ratio; CI 95% confidence interval. percent does not account of missing alleles at specific loci. significance (p < 0.05) is shown in bold.

Discussion

In this study, the genetic association of 20 possible biomarkers for the presence of IVD degenerative disease was determined. All SNPs tested were found to be within HWE and showed p-values ranging between 0.1007 and 0.9835 within the study population (Table 2). Genotype and allele distribution of the 20 SNPs were determined in study cohort (Tables 3 and 4). Among the SNPs analysed, 15 of the selected SNPs exhibited no statistically significant association with IVD degenerative disease within the study cohort (Table 3). The respective genotypes and alleles of the remaining 5 SNPs i.e. rs1304037 (CT P = 0.0456; C P = 0.0476), rs1800587 (GG P = 0.0249; A P = 0.0434), rs162509 (GG P = 0.0152; C P = 0.0112), rs632478 (GT P = 0.0249), and rs143383 (GA P = 0.0299; A P = 0.0474), however demonstrated significant associations between variant and IVD degenerative disease, prior to adjustment (Table 4). From our analysis, SNPs rs1304037, rs1800587, rs162509, rs632478 demonstrated increased odds of a positive diagnosis for IVD degenerative disease. Conversely, decreased odds of IVD degenerative disease were seen for rs143383.

Interleukin-1 (IL-1) is an inflammatory cytokine expressed in the IVD that is tied to the degradation of extracellular matrix components through the production of degradative enzymes, inhibition of proteoglycan resynthesis, cytokine upregulation, and through inhibition of extracellular matrix component production [7, 11, 26]. The IL-1α gene in particular is linked to an increased risk of IVD degenerative disease [7]. Hypersensitivity to IL-1α in IVD cells has been described as a significant motivator for degeneration, playing a key role in extracellular matrix metabolism and modic changes—an MRI trait associated with IVD degenerative disease [27]. To date, several IL-1α polymorphisms have been shown to be associated with IVD severity and modic changes, including the rs1800587 and rs1304037 variants [26].

The C allele of the IL-1α rs1304037 variant was reported to be associated with increased severity of IVD degenerative disease and the accompanying modic changes [26]. In this study, we have similarly shown a significant association between the rs1304037 variant and IVD degenerative disease (Table 4), particularly for the CT genotype and C allele prior to adjustment. Following adjustment, the C allele remained significantly associated with IVD degenerative disease within the study cohort. Thus, the findings presented here for rs1304037 are in accordance with those reported by Parera et al. [26]. With regard to the rs1800587 variant, the TT genotype, as compared to the CC genotype, has previously been shown to be associated with and increased risk of IVD degenerative disease in several studies [27–31]. Particularly, this association was demonstrated in a Caucasian population [27, 28], a Chinese Han population [29], and a Finnish population in studies investigating middle-aged men [30] and young girls aged 12–14 [31]. Thus, from the available literature, the C and T allele combination is the most reported, however, a G and A combination has also been described. To date, two studies have demonstrated an association with IVD degenerative disease for the G and A allelic combination for the variant in a Spanish population [32], as well as a Sri Lankan population [26]. In their studies, the A allele was shown to be associated with reduced severity of IVD degenerative disease and the accompanying modic changes [26, 32]. Presently, we similarly report the G and A allelic combination for rs1800587 within the study cohort. Unlike previous studies, however, our analysis revealed a significantly increased likelihood of IVD degenerative disease for the GA genotype and A allele (Table 4). These findings are contradictory to previous reports and thus merit further investigation within a larger study cohort. Nevertheless, the findings presented here reiterate the importance of the interleukins in IVD degenerative disease and its progression.

ADAMTS form a group of metalloproteinases possessing several important biological functions, such as extracellular matrix remodelling, procollagen processing, cell migration, and inflammatory processes [33, 34]. The binding of ADAMTS to extracellular matrix components is modulated via a thrombospondin structural domain which may lead to proteolysis [34]. ADAMTS-5 (aggrecanase-2) in particular has been identified as an important risk factor in the development of IVD degenerative disease [33]. Several studies have shown an association between the ADAMTS-5 rs162509 variant and IVD degenerative disease [35–37]. Early studies of the ADAMTS-5 rs162509 variant in the Chinese Han population reported the C and G allele combination and further showed no statistically significant association with IVD degenerative disease [38]. Interestingly, however, a later study of the same population reported a G and A allelic combination and further reported the G allele to be significantly higher in patients with IVD degenerative disease, as compared to healthy individuals [37]. Similarly, a study by Rajasekaran et al. also reported a significant association between rs165209 and the severity of IVD degenerative disease in an Indian population [36]. The present analysis demonstrated the C and G allele combination within the study cohort, and further that the CC genotype and C allele were significantly associated with the presence of IVD degenerative disease following adjustment and Bonferroni correction (Table 4). These findings are contradictory to those reported by Wu et al., however, and may indicate that the ADAMTS-5 rs165209 variant plays an integral role in the presence of IVD degenerative disease within the South African population. Based on this, further, more rigorous investigation of this variant within a larger cohort is essential.

Matrix metalloproteinases (MMPs) are the principal catabolic enzymes of the IVD and are the main mediators of extracellular matrix degradation that allow for normal remodelling and the abolishment of pathological tissues [14]. Degradation of the IVD’s extracellular matrix by MMP enzymes is important in the pathogenesis of IVD degeneration [8]. MMP-3 is reportedly one of the most significant proteoglycan-degrading enzymes [8, 14]. Specific conditions such as inflammation and mechanical loading can trigger the expression of the MMP-3 gene and the resulting IVD degeneration from this expression may, hereby, increase with time [14]. While available literature is limited, the MMP-3 rs63248 variant has been shown to play an integral role toward spinal bone mineral density and degenerative disease [39, 40]. Investigations into the role of MMP-3 rs63248 variant in IVD degenerative disease by Saberi et al. demonstrated a significant association within an Iranian population [40]. More specifically, they showed that the CC genotype was associated with a significantly increased risk of IVD degenerative disease, relative to the AA genotype, and was further suggested to be a contributing factor toward increased susceptibility within the studied population [40]. Presently, the alternate G and T allele combination was detected within the SA study cohort, for which our analysis revealed a significant association for the GT genotype (Table 4). Furthermore, the GT genotype remained significantly associated with the presence of IVD degenerative disease following adjustment and Bonferroni correction (Table 4). Accordingly, these findings add a valuable contribution to the limited body of literature associating this variant to the presence of IVD degenerative disease, and further highlight the importance of MMP-3 in the aetiology of this disease. Furthermore, these findings may be indicative of an integral role of the variant for IVD degenerative disease within the South African population. However, considering the limited size of the studied cohort, further analysis in a larger population is crucial.

Members of the growth differentiation factor (GDF) family are the most significant signalling molecules that maintain the homeostasis of the IVD, and its upregulation increases the expression of healthy cell marker genes [41]. Growth differentiation factor-5 (GDF-5), which is present in both normal and degenerated IVDs, has the capacity to regulate the composition of the extracellular matrix and plays an important role in the formation of soft tissues and the development of bones, cartilage, and ligaments [41]. The polymorphism on rs143383 is located in the 5’ non-coding region of GDF-5 gene and is thought to yield downregulation of GDF-5 gene expression, ultimately yielding an increased onset risk of IVD degenerative disease [42, 43]. The rs143883 variant has, accordingly, been shown to have a strong association with the development of hip dysplasia, osteoarthritis, and lumbar-related disease in several populations [43–47]. A study by Williams et al. linked the rs143383 variant with IVD degenerative disease, reporting a significantly increased risk of disc-space narrowing and osteophyte formation in Northern European women expressing the T allele [43]. Subsequent meta-analysis has similarly shown an association between the rs143383 variant and susceptibility to IVD degenerative disease, with the T allele conferring risk and the C allele protection [46]. A more recent meta-analysis has shown the CC genotype to confer an increased incidence of IVD degenerative disease in the Chinese Han population [47]. Present analysis of the rs143383 variant in the South African cohort reveals a G and A allelic combination for the rs143383 variant, along with a significant association with the presence of IVD degenerative disease prior to adjustment (Table 4). In particular, low ORs for the GA genotype (OR: 0.38) and A allele (OR: 0.57) were observed. These findings may be indicative of a potential protective function toward GDF-5 gene dysfunction in those expressing the G/A allelic combination, and further that GDF-5 may ultimately not be involved in the presence of IVD degenerative disease within the South African population. While interesting, adjusting for age and sex diminished the statistical significance of these observations—an occurrence likely due to the limited sample size used in this study. It is therefore imperative that the relationship of the rs143383 GDF-5 variant within the SA population be evaluated within a larger cohort. Moreover, determining if this potential protective function is unique to any specific racial group within the SA population would be beneficial.

It must also be mentioned that while several significant findings have been described in this study, the relatively small population size is a notable limitation, as this may have an impact on the statistical power. Moreover, the study utilised a mixed population and thus the influence of race toward the findings cannot be excluded. Thus, it is essential that these limitations are addressed in future studies.

Conclusion

To the best of our knowledge, this study represents the first of its kind to investigate the association of gene variants with IVD degenerative disease within the South African population. This study has shown that 5 of these gene variants were significantly associated with the presence of IVD degenerative disease, reflecting their integral roles in the development and possible progression of the disease. For this reason, further investigation is recommended within a larger study population, taking into account the possible influence of the various racial groups within South Africa.

Acknowledgements

The authors would like to express their immense gratitude to the Health Collective for their expertise, access to patient samples and records, and for their continued research support.

Keenau Pearce was partially supported as a Post-Doctoral Fellow by funding from the South African Medical Research Council (SAMRC) through its Division of Research Capacity Development under the Research Capacity Development Initiative (RCDI) Programme from funding received from the South African National Treasury. The content hereof is the sole responsibility of the authors and do not necessarily represent the official views of the SAMRC or the funders.

Author contributions

All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Keenau Pearce and Stephanie Less. The first draft of the manuscript was written by Keenau Pearce, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Funding

This study was made possible through funding by the South African Medical Research Counsil through its Division of Research Capacity Development under funding received from the South African National Treasury (Cape Town, Western Cape, South Africa).

Open access funding provided by University of the Western Cape.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval

This study was approved by the Senate Research Ethics Committee of the University of the Western Cape, South Africa [Ethics clearance number BM 22/4/7]. All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2016 [18].

Competing interests

The authors declare no competing interests.

Consent to participate

Samples were obtained from the participants with informed consent.

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
==== Refs
References

1. Kos N Gradisnik L Velnar T A brief review of the degenerative intervertebral disc disease Med Arch (Sarajevo Bosnia Herzegovina) 2019 73 421 424 10.5455/medarh.2019.73.421-424
Kos N, Gradisnik L, Velnar T (2019) A brief review of the degenerative intervertebral disc disease. Med Arch (Sarajevo Bosnia Herzegovina) 73:421–424. 10.5455/medarh.2019.73.421-424
2. Staszkiewicz R Gładysz D Gralewski M Pathomechanism of the IVDs degeneration and the role of neurotrophic factors and concentration of selected elements in Genesis of Low Back Pain Curr Pharm Biotechnol 2023 24 1164 1177 10.2174/1389201024666221021142904 36281863
Staszkiewicz R, Gładysz D, Gralewski M et al (2023) Pathomechanism of the IVDs degeneration and the role of neurotrophic factors and concentration of selected elements in Genesis of Low Back Pain. Curr Pharm Biotechnol 24:1164–1177. 10.2174/138920102466622102114290436281863
3. Diwan AD Melrose J Intervertebral disc degeneration and how it leads to low back pain JOR Spine 2023 6 e1231 10.1002/jsp2.1231 36994466
Diwan AD, Melrose J (2023) Intervertebral disc degeneration and how it leads to low back pain. JOR Spine 6:e1231. 10.1002/jsp2.123136994466
4. Oichi T Taniguchi Y Oshima Y Pathomechanism of intervertebral disc degeneration JOR Spine 2020 3 e1076 10.1002/jsp2.1076 32211588
Oichi T, Taniguchi Y, Oshima Y et al (2020) Pathomechanism of intervertebral disc degeneration. JOR Spine 3:e1076. 10.1002/jsp2.107632211588
5. Khumalo K Haffejee F Prevalence and associated risk factors of low back pain among users of a primary health care clinic serving semi-urban and rural settlements in KwaZulu-Natal, South Africa Afr Health Sci 2022 22 592 601 10.4314/ahs.v22i2.68 36407349
Khumalo K, Haffejee F (2022) Prevalence and associated risk factors of low back pain among users of a primary health care clinic serving semi-urban and rural settlements in KwaZulu-Natal, South Africa. Afr Health Sci 22:592–601. 10.4314/ahs.v22i2.6836407349
6. Dou Y, Sun X, Ma X et al (2021) Intervertebral disk degeneration: the Microenvironment and tissue Engineering Strategies. Front Bioeng Biotechnol 9. 10.3389/fbioe.2021.592118
7. Fiani B, Covarrubias C, Jarrah R (2021) Genetic predictors of early-onset spinal intervertebral disc degeneration: Part one of two. 10.7759/cureus.15182. Cureus
8. Feng Y Egan B Wang J Genetic factors in intervertebral disc degeneration Genes Dis 2016 3 178 185 10.1016/j.gendis.2016.04.005 27617275
Feng Y, Egan B, Wang J (2016) Genetic factors in intervertebral disc degeneration. Genes Dis 3:178–185. 10.1016/j.gendis.2016.04.00527617275
9. Ou-Yang DC Kleck CJ Ackert-Bicknell CL Genetics of Intervertebral Disc Degeneration Curr Osteoporos Rep 2023 21 56 64 10.1007/s11914-022-00769-0 36680730
Ou-Yang DC, Kleck CJ, Ackert-Bicknell CL (2023) Genetics of Intervertebral Disc Degeneration. Curr Osteoporos Rep 21:56–64. 10.1007/s11914-022-00769-036680730
10. Pan H Li H Guo S The mechanisms and functions of TNF-α in intervertebral disc degeneration Exp Gerontol 2023 174 112119 10.1016/j.exger.2023.112119 36758650
Pan H, Li H, Guo S et al (2023) The mechanisms and functions of TNF-α in intervertebral disc degeneration. Exp Gerontol 174:112119. 10.1016/j.exger.2023.11211936758650
11. Kepler CK Ponnappan RK Tannoury CA The molecular basis of intervertebral disc degeneration Spine J 2013 13 318 330 10.1016/j.spinee.2012.12.003 23537454
Kepler CK, Ponnappan RK, Tannoury CA et al (2013) The molecular basis of intervertebral disc degeneration. Spine J 13:318–330. 10.1016/j.spinee.2012.12.00323537454
12. Martirosyan NL, Patel AA, Carotenuto A et al (2016) Genetic alterations in intervertebral disc disease. 10.3389/fsurg.2016.00059. Front Surg 3:
13. Munir S Rade M Määttä JH Intervertebral Disc Biology: genetic basis of Disc Degeneration Curr Mol Biol Rep 2018 4 143 150 10.1007/s40610-018-0101-2 30464887
Munir S, Rade M, Määttä JH et al (2018) Intervertebral Disc Biology: genetic basis of Disc Degeneration. Curr Mol Biol Rep 4:143–150. 10.1007/s40610-018-0101-230464887
14. Teles Filho RV Abe G de Daher M Genetic influence in disc degeneration - systematic review of literature Rev Bras Ortop 2020 55 131 138 10.1055/s-0039-1692626
Teles Filho RV, Abe G, de Daher M MT (2020) Genetic influence in disc degeneration - systematic review of literature. Rev Bras Ortop 55:131–138. 10.1055/s-0039-1692626
15. Ikediobi O Aouizerat B Xiao Y Analysis of pharmacogenetic traits in two distinct South African populations Hum Genomics 2011 5 265 282 10.1186/1479-7364-5-4-265 21712189
Ikediobi O, Aouizerat B, Xiao Y et al (2011) Analysis of pharmacogenetic traits in two distinct South African populations. Hum Genomics 5:265–282. 10.1186/1479-7364-5-4-26521712189
16. Warnich L Drögemöller BI Pepper MS Pharmacogenomic Research in South Africa: lessons learned and Future opportunities in the Rainbow Nation Curr Pharmacogenomics Person Med 2011 9 191 207 10.2174/187569211796957575 22563365
Warnich L, Drögemöller BI, Pepper MS et al (2011) Pharmacogenomic Research in South Africa: lessons learned and Future opportunities in the Rainbow Nation. Curr Pharmacogenomics Person Med 9:191–207. 10.2174/18756921179695757522563365
17. Zhang C Hansen MEB Tishkoff SA Advances in integrative African genomics Trends Genet 2022 38 152 168 10.1016/j.tig.2021.09.013 34740451
Zhang C, Hansen MEB, Tishkoff SA (2022) Advances in integrative African genomics. Trends Genet 38:152–168. 10.1016/j.tig.2021.09.01334740451
18. Mellin-Olsen J Filipescu D Mahajan RP Shapiro FE Helsinki Declaration 2016: global patient safety ASA Monit 2016 80 22 24
Mellin-Olsen J, Filipescu D, Mahajan RP, Shapiro FE (2016) Helsinki Declaration 2016: global patient safety. ASA Monit 80:22–24
19. Staunton C Tschigg K Sherman G Data protection, data management, and data sharing: stakeholder perspectives on the protection of personal health information in South Africa PLoS ONE 2021 16 e0260341 10.1371/journal.pone.0260341 34928950
Staunton C, Tschigg K, Sherman G (2021) Data protection, data management, and data sharing: stakeholder perspectives on the protection of personal health information in South Africa. PLoS ONE 16:e0260341. 10.1371/journal.pone.026034134928950
20. Wentzel W (2021) The Protection of Personal Information Act: its effect on clinical practice and Health Research. South Afr J Occup Ther 51. 10.17159/2310-3833/2021/vol51n2a1
21. Flicek P Amode MR Barrell D Ensembl 2012 Nucleic Acids Res 2012 40 D84 D90 10.1093/nar/gkr991 22086963
Flicek P, Amode MR, Barrell D et al (2012) Ensembl 2012. Nucleic Acids Res 40:D84–D90. 10.1093/nar/gkr99122086963
22. Leat N Benjeddou M Davison S Nine-locus Y-chromosome STR profiling of caucasian and xhosa populations from Cape Town, South Africa Forensic Sci Int 2004 144 73 75 10.1016/j.forsciint.2004.02.022 15240024
Leat N, Benjeddou M, Davison S (2004) Nine-locus Y-chromosome STR profiling of caucasian and xhosa populations from Cape Town, South Africa. Forensic Sci Int 144:73–75. 10.1016/j.forsciint.2004.02.02215240024
23. Clarke GM Anderson CA Pettersson FH Basic statistical analysis in genetic case-control studies Nat Protoc 2011 6 121 133 10.1038/nprot.2010.182 21293453
Clarke GM, Anderson CA, Pettersson FH et al (2011) Basic statistical analysis in genetic case-control studies. Nat Protoc 6:121–133. 10.1038/nprot.2010.18221293453
24. Peakall R Smouse P GENALEX 6: genetic analysis in Excel. Population genetic software for teaching and research Mol Ecol Notes 2006 6 288 295 10.1111/j.1471-8286.2005.01155.x
Peakall R, Smouse P (2006) GENALEX 6: genetic analysis in Excel. Population genetic software for teaching and research. Mol Ecol Notes 6:288–295. 10.1111/j.1471-8286.2005.01155.x
25. Peakall R Smouse PE GenAlEx 6.5: genetic analysis in Excel. Population genetic software for teaching and research—an update Bioinformatics 2012 28 2537 2539 10.1093/bioinformatics/bts460 22820204
Peakall R, Smouse PE (2012) GenAlEx 6.5: genetic analysis in Excel. Population genetic software for teaching and research—an update. Bioinformatics 28:2537–2539. 10.1093/bioinformatics/bts46022820204
26. Perera RS Dissanayake PH Senarath U Single nucleotide variants of candidate genes in Aggrecan Metabolic Pathway are Associated with lumbar disc degeneration and Modic Changes PLoS ONE 2017 12 e0169835 10.1371/journal.pone.0169835 28081267
Perera RS, Dissanayake PH, Senarath U et al (2017) Single nucleotide variants of candidate genes in Aggrecan Metabolic Pathway are Associated with lumbar disc degeneration and Modic Changes. PLoS ONE 12:e0169835. 10.1371/journal.pone.016983528081267
27. Liu J, Chen Y, Shan X, Wang H (2022) Association between CILP and IL-1α polymorphisms and phenotype-dependent intervertebral disc degeneration susceptibility: a meta-analysis. Front Genet 13. 10.3389/fgene.2022.1005393
28. Azharuddin A Ilmawan M Fajar JK The role of single nucleotide polymorphisms of IL-1A -889C > T (rs1800587), TNF-A -238G > A (rs361525), and VDR TaqI (rs731236) on susceptibility to herniated nucleus pulposus: a systematic review and meta-analysis F1000Research 2021 10 419 10.12688/f1000research.53235.3 34504685
Azharuddin A, Ilmawan M, Fajar JK et al (2021) The role of single nucleotide polymorphisms of IL-1A -889C > T (rs1800587), TNF-A -238G > A (rs361525), and VDR TaqI (rs731236) on susceptibility to herniated nucleus pulposus: a systematic review and meta-analysis. F1000Research 10:419. 10.12688/f1000research.53235.334504685
29. Chen Y, Ma H, Bi D, Qiu B (2018) Association of interleukin 1 gene polymorphism with intervertebral disc degeneration risk in the Chinese Han population. Biosci Rep 38. 10.1042/BSR20171627
30. Karppinen J Solovieva S Luoma K Modic changes and interleukin 1 gene locus polymorphisms in occupational cohort of middle-aged men Eur Spine J 2009 18 1963 1970 10.1007/s00586-009-1139-x 19701653
Karppinen J, Solovieva S, Luoma K et al (2009) Modic changes and interleukin 1 gene locus polymorphisms in occupational cohort of middle-aged men. Eur Spine J 18:1963–1970. 10.1007/s00586-009-1139-x19701653
31. Eskola PJ Kjaer P Daavittila IM Genetic risk factors of disc degeneration among 12-14-year-old Danish children: a population study Int J Mol Epidemiol Genet 2010 1 158 165 21537388
Eskola PJ, Kjaer P, Daavittila IM et al (2010) Genetic risk factors of disc degeneration among 12-14-year-old Danish children: a population study. Int J Mol Epidemiol Genet 1:158–16521537388
32. Polo YL Borda J Szczypiorska M Bartolomé N Clinical and genetic characteristics of ankylosing spondylitis patients with peripheral arthritis at disease onset Clin Exp Rheumatol 2019 37 215 221 30299251
Polo YL, Borda J, Szczypiorska M, Bartolomé N et al (2019) Clinical and genetic characteristics of ankylosing spondylitis patients with peripheral arthritis at disease onset. Clin Exp Rheumatol 37:215–22130299251
33. Jiang L, Lin J, Zhao S et al (2021) ADAMTS5 in Osteoarthritis: Biological functions, Regulatory Network, and potential targeting therapies. Front Mol Biosci 8. 10.3389/fmolb.2021.703110
34. Liang H Luo R Li G The proteolysis of ECM in intervertebral disc degeneration Int J Mol Sci 2022 23 1715 10.3390/ijms23031715 35163637
Liang H, Luo R, Li G et al (2022) The proteolysis of ECM in intervertebral disc degeneration. Int J Mol Sci 23:1715. 10.3390/ijms2303171535163637
35. Huo J-Z, Ji X-H, Su Z-Y et al (2018) Association of ADAMTS4 and ADAMTS5 polymorphisms with musculoskeletal degenerative diseases: a systematic review and meta-analysis. Biosci Rep 38. 10.1042/BSR20181619
36. Rajasekaran S Kanna RM Senthil N Genetic susceptibility of lumbar degenerative disc disease in young Indian adults Eur Spine J 2015 24 1969 1975 10.1007/s00586-014-3687-y 25416170
Rajasekaran S, Kanna RM, Senthil N et al (2015) Genetic susceptibility of lumbar degenerative disc disease in young Indian adults. Eur Spine J 24:1969–1975. 10.1007/s00586-014-3687-y25416170
37. Jiang H Yang Q Jiang J Association between COL11A1 (rs1337185) and ADAMTS5 (rs162509) gene polymorphisms and lumbar spine pathologies in Chinese Han population: an observational study BMJ Open 2017 7 e015644 10.1136/bmjopen-2016-015644 28583914
Jiang H, Yang Q, Jiang J et al (2017) Association between COL11A1 (rs1337185) and ADAMTS5 (rs162509) gene polymorphisms and lumbar spine pathologies in Chinese Han population: an observational study. BMJ Open 7:e015644. 10.1136/bmjopen-2016-01564428583914
38. Wu N Chen J Liu H The involvement of ADAMTS-5 genetic polymorphisms in predisposition and diffusion tensor imaging alterations of lumbar disc degeneration J Orthop Res 2014 32 686 694 10.1002/jor.22582 24415654
Wu N, Chen J, Liu H et al (2014) The involvement of ADAMTS-5 genetic polymorphisms in predisposition and diffusion tensor imaging alterations of lumbar disc degeneration. J Orthop Res 32:686–694. 10.1002/jor.2258224415654
39. Jehan F Zarka M de la Houssaye G New insights into the role of matrix metalloproteinase 3 in bone FASEB BioAdvances 2022 4 524 538 10.1096/fba.2021-00092 35949513
Jehan F, Zarka M, de la Houssaye G et al (2022) New insights into the role of matrix metalloproteinase 3 in bone. FASEB BioAdvances 4:524–538. 10.1096/fba.2021-0009235949513
40. Saberi A Salehi Z Naderinabi B Genetic dimension of intervertebral disc degeneration: polymorphism of matrix metalloproteinase 1 and 3 in the north Iranian population Turk Neurosurg 2017 10.5137/1019-5149.JTN.19978-17.0
Saberi A, Salehi Z, Naderinabi B et al (2017) Genetic dimension of intervertebral disc degeneration: polymorphism of matrix metalloproteinase 1 and 3 in the north Iranian population. Turk Neurosurg. 10.5137/1019-5149.JTN.19978-17.0
41. Lv B Gan W Cheng Z Current insights into the maintenance of structure and function of intervertebral disc: a review of the Regulatory role of growth and differentiation Factor-5 Front Pharmacol 2022 13 842525 10.3389/fphar.2022.842525 35754493
Lv B, Gan W, Cheng Z et al (2022) Current insights into the maintenance of structure and function of intervertebral disc: a review of the Regulatory role of growth and differentiation Factor-5. Front Pharmacol 13:842525. 10.3389/fphar.2022.84252535754493
42. Reynard LN Bui C Syddall CM Loughlin J CpG methylation regulates allelic expression of GDF5 by modulating binding of SP1 and SP3 repressor proteins to the osteoarthritis susceptibility SNP rs143383 Hum Genet 2014 133 1059 1073 10.1007/s00439-014-1447-z 24861163
Reynard LN, Bui C, Syddall CM, Loughlin J (2014) CpG methylation regulates allelic expression of GDF5 by modulating binding of SP1 and SP3 repressor proteins to the osteoarthritis susceptibility SNP rs143383. Hum Genet 133:1059–1073. 10.1007/s00439-014-1447-z24861163
43. Williams FMK Popham M Hart DJ GDF5 single-nucleotide polymorphism rs143383 is associated with lumbar disc degeneration in northern European women Arthritis Rheum 2011 63 708 712 10.1002/art.30169 21360499
Williams FMK, Popham M, Hart DJ et al (2011) GDF5 single-nucleotide polymorphism rs143383 is associated with lumbar disc degeneration in northern European women. Arthritis Rheum 63:708–712. 10.1002/art.3016921360499
44. Zhou H Zhu F Qiu Y [Effect of intervertebral disc degeneration on spinal flexibility in patients with degenerative lumbar scoliosis] Zhonghua Wai Ke Za Zhi 2014 52 739 744 25573212
Zhou H, Zhu F, Qiu Y et al (2014) [Effect of intervertebral disc degeneration on spinal flexibility in patients with degenerative lumbar scoliosis]. Zhonghua Wai Ke Za Zhi 52:739–74425573212
45. Gologorsky Y Chi J Genetic predisposition to lumbar disc degeneration Neurosurgery 2014 74 N10 N11 10.1227/NEU.0000000000000275 24435142
Gologorsky Y, Chi J (2014) Genetic predisposition to lumbar disc degeneration. Neurosurgery 74:N10–N11. 10.1227/NEU.000000000000027524435142
46. Jiang L, Wang Y, Zhu X et al (2017) A single nucleotide polymorphism in the GDF5 gene (rs143383) may contribute to the increased risk of osteoarthritis and lumbar disc degeneration: an updated Meta-analysis. J Bone Res 05. 10.4172/2572-4916.1000183
47. Wang Z Li Y Wang Y Association between GDF5 single nucleotide polymorphism rs143383 and lumbar disc degeneration Exp Ther Med 2018 16 1900 1904 10.3892/etm.2018.6382 30186416
Wang Z, Li Y, Wang Y et al (2018) Association between GDF5 single nucleotide polymorphism rs143383 and lumbar disc degeneration. Exp Ther Med 16:1900–1904. 10.3892/etm.2018.638230186416
