
==== Front
Mater Sociomed
Mater Sociomed
Mater Sociomed
Materia Socio-Medica
1512-7680
1986-597X
AVICENA, d.o.o., Sarajevo Bosnia and Herzegovina

MSM-35-8
10.5455/msm.2023.35.8-12
Original Paper
Genetically Homogeneous or Heterogeneous Population – Distribution of the Recessive Allele in Selected Qualitative Characteristics of Selected Working-Age Population Sample
Metovic Azra 1
Musanovic Jasmin 1
Lujinovic Almira 2
Pepic Esad 3
Prstojevic-Kovacevic Jelena 4
1 Faculty of Medicine, Department of Medical Biology with Human genetics, University of Sarajevo
2 Faculty of Medicine, Department of Anatomy, University of Sarajevo, Bosnia and Herzegovina Bosnia and Herzegovina
3 Faculty of Medicine, Department of Patophysiology, University of Sarajevo, Bosnia and Herzegovina
4 Clinical Center University of Sarajevo, Bosnia and Herzegovina
Corresponding author: Azra Metovic, PhD. Department of medical Biology with Human genetics, Faculty of Medicine, University of Sarajevo. Address: Cekalusa 90, 71000 Sarajevo, Bosnia and Herzegovina. Phone: +38761278142. address: azra.metovic@mf.unsa.ba. ORCID ID: https://orcid.org 0000-0003-2305-4995.
3 2023
35 1 812
20 1 2023
05 3 2023
© 2023 Azra Metovic, Jasmin Musanovic, Almira Lujinovic, Esad Pepic, Jelena Prstojevic-Kovacevic
2023
https://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background:

The genetic structure of each population can be explained according to the frequency of genes and their allelic variants, genotypes, and phenotypes.

Objective:

To analyze the genetic heterogeneity of the working-age population from the area of Sarajevo Canton based on classic genetic markers. The studied parameters of genetic heterogeneity were assessed by the relative frequency of the recessive allele for static-morphological traits (earlobe shape, chin shape, hairiness of the middle digital phalanx, bending of the distal phalanx of the little finger and digital index) and dynamic-morphological traits (rolling of the tongue into a groove, extensibility of the proximal thumb knuckle, extensibility of the distal thumb knuckle, the way the forearms are crossed, and the way the fists are made).

Results:

The results of the t-test showed a significant difference in the manifestation of the recessive homozygote for the observed parameters of qualitative variation in the subsamples of men and women. Only for two traits (attached earlobe and hyperextensibility of the distal knuckle of the thumb). The selected sample represent a relatively genetically homogenous population.

Conclusion:

This study serves as a valuable source of data for future research and the formation of a genetic database in Bosnia and Herzegovina.

genetically homogeneous population
genetically heterogeneous population
recessive allele
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pmc1. BACKGROUND

According to the nature of within-group variability, all traits can be divided into two basic categories: qualitative and quantitative (1, 2). Quantitative traits are polygenic determined by a larger number of genes, while qualitative traits are determined by one gene or a small number of genes (so-called monogenic or oligogenic determination) (3, 4). Genes that determine qualitative properties have an obvious influence on the phenotype, so we can easily detect their mutations. In population genetic studies of variability, the analysis of phenotypic characteristics is used, which are easy to observe by observation and measurement (5, 6). All traits, qualitative and quantitative, can be classified into: morphological, biochemical, physiological, psychological or into combined categories such as: morpho-physiological, biochemical-physiological, psycho-physiological (3, 7).

Qualitative traits are under the control of one or fewer genes, so it is relatively easy to determine the types of alleles and calculate their frequency in a certain sample. Research into the genetic structures of an individual population, with regard to the assessment of qualitative variations, includes observation and analysis of phenotypic forms (8, 9). Such genetic study is insufficiently represented in the areas of Bosnia and Herzegovina. With this study, we contribute to a higher level of knowledge of qualitative hereditary variation, and therefore of individual genetic structures. Morphological properties are classified according to several criteria, and most often they are classified into static-morphological and dynamic-morphological properties (10).

Table 1. Analyzed static-morphological properties

Phenotype systems	Observed allele	Dominant genotype/phenotype	Recessive genotype/phenotype	
Earlobes	E> e	EE,Ee /free earlobe	ee/attached earlobe	
Cleft in chin	CH>ch	CHCH,ChCh/cleft	chch /Round	
Hairiness digital phalanx finger	D>d	DD,Dd with hair	dd / no-hairiness phalanx	
Flexion of the distal phalanx of the little finger	F > f	FF,Ff/ curved	ff/ strait	
Digit Index	D >d	Male DD,Dd/short	dd/long	
Female DD,Dd/long	dd/short	

Table 2. Analyzed dynamic-morphological properties

Phenotype systems	Observed allele	Dominant genotype/phenotype	Recessive genotype/phenotype	
Tongue rolling (side edges up)	R > r	RR, Rr Roller	rr/noroller	
Extensibility proximal knuckle of the thumb	T>t	TT, Tt/ no extensibility	tt/ hyper extensibility	
Extensibility distal knuckle of the thumb	DK>dk	DK, Dk/ no extensibility	dk/ hyper extensibility	

Table 3. Genetic determination of dynamic-morphological properties

Phenotype systems	Alternative phenotypes	
The manner of making fists	right/left	
Crossing the forearms	right/left	

Static-morphological traits include those phenotypic systems whose alternative variants are determined by direct observation of the corresponding body structure elements, without special requirements.

We mainly assess genetic variation in population genetics by determining the frequency of genes and alleles within populations and if they change over time and/or space. The proportion of a specific genotype within a population is called genotype frequency. The proportion of a particular phenotype within a population is called the phenotype frequency. Allele frequency is the share of a certain allele within the population (11-13).

2. OBJECTIVE

The aims of this study were: a) To determine the phenotypes variation of certain statistical-morphological features among middle-aged subjects; b) Determine the variation of the phenotypes of certain dynamic-morphological features among middle-aged subjects; c) To determine the statistical significance of observed differences in the distribution of observed phenotypic characteristics between sexes with regard to the studied sample.

3. MATERIAL AND METHODS

The data for this experimental study was collected by direct testing and surveying 200 respondents aged between 20-55 years in one company from Sarajevo. The study analyzed five static-morphological and five dynamic morphological traits (Tables 1, 2, 3).

The phenomenon of reversal of dominance, which refers to cases when, under the influence of gender-specific regulators, there is a change in the direction of dominance among the alleles of a given gene locus. noted (unequal) frequency of alternative digital index phenotypes by sexually defined categories, due to the dominance of the allele for the long index finger in women, i.e. its recessiveness in men, i.e. The short index finger allele is dominant in the male and recessive in the female sex (14).

Manifestation of alternative phenotypes of these two phenotypic systems (Table 3) is independent of gender and age, and is not related to a person’s right-handedness or left-handedness.

When collecting data on static-morphological characteristics, the observation method was applied, while the most acceptable method was the demonstration method when examining dynamic-morphological properties (2)-

After categorizing the data, the data was processed by applying the appropriate ones mathematical-statistical and population-genetic methods (15, 16).

From the absolute frequency of the recessive phenotype (Rf), the relative frequency of the recessive allele (q) was calculated, according to the formulas:

R=R(f)NteQ=R

Where q is the relative frequency of the recessive allele (q)

N – the number of subjects;

R(f)–absolute frequency of the recessive phenotype;

R – relative frequency of recessive homozygote.

Statistical analysis

Standard methods of descriptive statistics were used in the statistical processing of the data. For comparison, the Student t test was used, while the comparison in the last two tables was tested by chi-square or by Fisher‘s exact test.

4. RESULTS

The obtained data on the relative frequency of the recessive phenotype, the recessive allele and the t-test with its p-values are tabulated for each individually analyzed characteristics.

Out of 200 respondents, 94 respondents were men and 106 were women.

Figure 1. Age structure of respondents

In terms of age, most respondents belonged to the group between 21 and 30 years old (54%). 27% of respondents were in the age group from 31-40 years. Respondents aged 41-50 accounted for 15%, and respondents aged 51-60 were the least represented with 4% (Figure 1).

Figure 2 present a comparison of the relative frequency of the recessive homozygote for the static-morphological and dynamic-morphological characteristics of the compared categories of both sexes.

In most of the examined static-morphological traits, the frequency of the recessive allele is higher in the subpopulation of women (Figure 2) and the results of the t-test showed a statistically significant difference only in the comparison of the increased earlobe phenotype (Table 4).

The analysis of the recessive phenotype and the distribution of the recessive allele in dynamic morphological traits shows that there are differences in the gender distribution of the recessive phenotype and the recessive allele, but the differences are significant only for the phenotypic property “hyper extensibility” of the distal joint of the thumb (Table 4).

From Figure 2 and Table 4 it can be seen that a slightly higher frequency of the recessive phenotype “attached” earlobe was recorded in the subpopulation of female subjects (q =0.70) compared to males (q=0.59), and the observed difference in the distribution of the recessive allele is statistically significant (t %= -2.007, p= 0.046). The recessive phenotype round chin is more common in females (q=0.76) compared to males (q=0.69), but this difference is not statistically significant (t %= -1.654; p= 0.099). A slightly higher frequency of the no-hairiness recessive phenotype was observed in the population to females (q= 0.81) compared to the males (q=0.75), but the observed difference was not statistically significant (t= -1.245, p=0.215).

Recessive phenotype “straight” regarding the distal phalanx of the little finger was observed in 34 males subject and in 48 female subjects, but this difference is not statistically significant (t%= -1.310; p=0.192).

In relation to the dynamic morphological trait digital index, a slightly higher frequency of recessive phenotype and recessive allele was observed in males (Rf= 0.45; q= 0.80), but this difference is not statistically significant (t= 1.268; p=0.206).

Although a variation in the distribution of the recessive phenotype “non-roller” was observed between the sexes, with a slightly higher frequency in the female sex (Rf= 0.45; q=0.67) compare to male sex (Rf= 0.40; q= 0.63), this difference is not significant (t %0 -0.690; p= 0.491).

The difference in the distribution of the recessive phenotype hyper extensibility of the proximal knuckle of the thumb is insignificant (t%=0.421; p= 0.064 (Table 4).

Analyzing the obtained values of the frequency of the recessive phenotype hyper extensible distal knuckle (hitchhiker’s inches), a higher frequency was observed in males (Rf=0.34; q=0.58) compared to females subjects (Rf=0,17; q=0.41, Table 4), and the difference in the frequency of this phenotype and the recessive allele is statistically significant (t%=2.784; p= 0.006) (Table 4). The frequency of recessive phenotype, recessive alleles and statistical significance of observed differences between genders. The results from Table 5 show that 56 male subjects make their fists “to the right”, that is 59.6%, and 38 male respondents make fists “to the left”, which is 40.4%.

Figure 2. Comparative presentation of the relative frequency of the recessive homozygote for selected morphological traits

Among women, 62 of them make their fists “to the right”, or 58.5%, and 44 of them make their fists to the “left”, which in percentage terms represents 41.5%.

The results of the chi square test and p value show that the difference in the distribution of alternative phenotype between the sexes is not significant when it comes to the manner of making fists (χ2= 0.0001; p= 0.991).

By analyzing the results of the way of crossing the forearms, 42.6% of male subjects cross their forearms “right” and 57.4% cross their forearms “left” (Table 5).

Out of a total of 106 women, 66% make their fists “to the right”, while 34% cross their forearms to the left (Table 5). The difference between the sexes is significant as far as the crossing of the forearms is concerned (χ2 =10.173; p=0.001)

Table 4. The frequency of recessive phenotype, recessive alleles and statistical significance of observed differences between genders

Phenotype systems	Recessive phenotype	Gender	N	R	Rf	q	t%	P	
Earlobes	Attached earlobe	Male	94	33	0.35	0.59	-2.007	0.046	
Female	106	52	0.49	0.70	
Cleft in chin	Round	Male	94	44	0.47	0.69	-1.654	0.099	
Female	106	62	0.58	0.76	
Hairiness digital phalanx finger	No-hairiness phalanx	Male	94	54	0.57	0.75	-1.245	0.215	
Female	106	70	0.66	0.81	
Flexion of the distal phalanx of the little finger	Strait	Male	94	34	0.36	0.60	-1.310	0.192	
Female	106	48	0.45	0.67	
Digital index	Long	Male	94	42	0.45	0.80	1.268	0.206	
Short	Female	106	38	0.36	0.60	
Tongue rolling (side edges up)	No roller	Male	94	38	0.40	0.63	-0.690	0.491	
Female	106	48	0.45	0.67	
Extensibility proximal knuckle of the thumb	Hyper extensibility	Male	94	31	0.33	0.57	0.421	0.674	
Female	106	32	0.30	0.55	
Extensibility distal knuckle of the thumb	Hyper extensibility	Male	94	32	0.34	0.58	2.784	0.006	
Female	106	18	0.17	0.41	

Table 5. The manner of making fists and crossing the forearms by gender

	Male	Female	χ2	P	
N	%	N	%	
The manner of making fists	Right	56	59.6	62	58.5	0.0001	0.991	
Left	38	40.4	44	41.5	
Crossing the forearms	Right	40	42.6	70	66.0	10.173	0.001	
Left	54	57.4	36	34.0	
Total	94	100.0	106	100.0			

5. DISCUSSION

By analyzing the frequency of static and dynamic-morphological properties in a selected sample of the working-age population of Sarajevo Canton, it was concluded that the frequency of the recessive phenotype for most of the analyzed static-properties is slightly higher in the category of the female gender compared to the male gender, which was also observed by the analysis of the t-test.

Total frequency of recessive allele according phenotype attached earlobes is q=0.66. This recessive phenotype shows significant difference in the distribution between the sexes. Higher frequency was observed in female sex (t%= -2.007; p=0.046).

The results of this study indicate that the frequency of recessive phenotype phalanx phenotype without hair is slightly higher (62%.) compared to the results of similar studies that indicate the frequency of this property in the United States 40%, Australia 52% and Israel 42% (17).

The digital index represents the different relationships between the index finger and the ring finger. This property is characterized by the appearance of a reversal of dominance, which means that in the male sex the allele for the short index finger is dominant, and for the female sex the index finger is a longer index finger than the ring finger represents the dominant property. The results of our study show that the frequency of phenotypes the long index finger reports 55 %, so it the approximate value of the results of similar studies (18).

The tongue rolling as a simple two-dimensional feature, where allele for rolling is dominates over the allele that causes the inability to rolling the tongue, and the allele ratio of an autosomal gene loci is completely dominant.

Comparing results this study for recessive phenotype non roller 55% with the results from the literature shows that the frequency of this phenotype in relation to the total sample fits into the range of variation of the frequency of this phenotype in the Bosnian population and parts of the world population (19).

By comparing the frequencies of the recessive homozygote of the dynamic-morphological properties, significant differences were recorded in the expression of only one recessive phenotype. Higher frequency was found of the phenotype “hyper extensibility of the distal knuckle of the thumb” in male sex (t=2.784; p=0.006).

By analyzing the summarized data of observed differences in the recessive phenotype of static and dynamic morphological properties, it was concluded that for most of the observed phenotypic indicators, no statistically significant difference in distribution between male and female.

Indicators of genetic heterogeneity of observed traits (from Cavalli-Sforza, Bodmer, 1999), are ranked by degree genetic differentiation. According to the degree of genetic heterogeneity, all values of this indicator for each individually studied property fall into the category of small genetic differentiation.

Based on the analysis of the complete results using phenotypic genetic markers, it was observed that there is no difference between the genetic structure of male and female subjects.

The results of this study are in correlation with similar studies (20, 21) whose results also indicate approximately equal frequencies of recessive phenotypes for most of the analyzed properties.

Analyzed samples in similar studies (22, 23) as well as our analyzed sample indicate a relatively genetically homogeneous population when it comes to gender differences in the observed parameters of qualitative variation.

6. CONCLUSION

The low values of the studied indicators of genetic heterogeneity can be interpreted as a consequence of the effects of genetic drift and poorly expressed propagation mobility. With this study, we can complete the incomplete database of population genetics in the area of Sarajevo.

This study serves as a valuable source of data for future research and the formation of a genetic database in Bosnia and Herzegovina.

Our suggestion is that in future research, the database should be completed by analyzing the complete parameters of qualitative variation and provide as detailed an explanation as possible about the influence of gender on the genetic structure of populations.

Author's contribution:

All authors were involved in all steps of preparation this article. Final proofreading was made by the first author.

Conflict of interest:

None declared.

Financial support and sponsorship:

Nil.
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