
==== Front
medRxiv
MEDRXIV
medRxiv
Cold Spring Harbor Laboratory

10.1101/2024.08.16.24312065
preprint
1
Article
Quantifying the Spectrum of Early Motor and Language Milestones in Sex Chromosome Trisomy
Thompson Talia http://orcid.org/0000-0001-6512-9743

Bothwell Samantha http://orcid.org/0000-0002-1616-8137

Janusz Jennifer http://orcid.org/0000-0002-6877-0947

Wilson Rebecca
Howell Susan http://orcid.org/0000-0001-7115-2165

Davis Shanlee http://orcid.org/0000-0002-0304-9550

Swenson Karli http://orcid.org/0000-0003-0513-7308

Martin Sydney http://orcid.org/0009-0006-5671-0142

Kowal Karen
Ikomi Chijioke http://orcid.org/0000-0002-0630-2355

Despradel Maria http://orcid.org/0009-0005-7413-1649

Ross Judith http://orcid.org/0000-0002-8613-2498

Tartaglia Nicole http://orcid.org/0000-0002-8529-6722

19 8 2024
2024.08.16.24312065https://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which allows reusers to copy and distribute the material in any medium or format in unadapted form only, for noncommercial purposes only, and only so long as attribution is given to the creator.
http://medrxiv.org/lookup/doi/10.1101/2024.08.16.24312065
nihpp-2024.08.16.24312065.pdf
Background and objectives: Sex chromosome trisomy (SCT) is a common chromosomal abnormality associated with increased risks for early developmental delays and neurodevelopmental disorders later in childhood. Our objective was to quantify the spectrum of early developmental milestones in SCT. We hypothesized later milestone achievement in SCT than the general population. Methods: Data were collected as part of the eXtraordinarY Babies Study, a prospective natural history of developmental and health trajectories in a prenatally identified sample of infants with SCT. Parent reported, clinician-validated, early motor and language milestones were collected at 2, 6, 12, 18, 24, and 36-months. Age distributions of milestone achievement were compared with normative data. Results: In all SCT conditions, compared with normative data, there was increased variability and a later median age of skill development across multiple gross motor and expressive language milestones. Results also show a significant amount of overlap with the general pediatric population, suggesting that for many children with prenatally identified SCT, early milestones present within, or close to, the expected timeline. Conclusions: As increasing numbers of infants with prenatal SCT diagnoses present at pediatric practices, we provide an evidence-based schedule of milestone achievement in SCT as a tool for pediatricians and families. Detailed data on SCT milestones can support clinical interpretation of milestone achievement. Increased variability and later median age of milestone acquisition in SCT compared to norms support consideration of all infants with SCT as high risk.
==== Body
pmc
