Work

Maternal age and the parental origin of trisomy 21 in Libyan individuals with Down syndrome: a preliminary familial D21S11 STR study

Year: 2026

Type: article

Abstract: Down syndrome (DS) is the most prevalent chromosomal disorder worldwide and is primarily caused by chromosome 21 nondisjunction (Ch21 NDJ). Categorizing trisomy 21 cases by parental origin allows a more precise assessment of maternal age (MA) as a DS risk factor. This study aimed to investigate the association between MA and parental allele transmission patterns at the D21S11 locus in individuals with DS. A familial-based study was conducted by collecting blood samples from 55 DS Libyan families, categorizing into two groups based on MA (<35 years and ≥35 years). Short tandem repeat analysis of D21S11 marker on Ch21 was used to trace allelic transmission from parents to offspring. The parental NDJ errors were traceable in 24 (58.5%) of 41 informative families, with maternal and paternal NDJ errors accounting for 20/24 (83.3%) and 4/24 (16.7%), respectively. Given the limited traceability rate, this investigation should be considered a preliminary study. Among the 24 informative cases, maternal-origin trisomy accounted for 8 of 10 cases (80.0%) in mothers aged <35 years and 12 of 14 cases (85.7%) in mothers aged ≥35 years. The present results suggest that MA may be associated with the distribution of trisomy 21 based on D21S11 parental allele transmission patterns; however, no statistically significant association was detected in the present cohort ( P = 0.563). Although additional Ch21 markers are needed, this study provides preliminary insights into MA-related patterns of allele transmission in Libyan individuals with DS.

Source: Human Genome Variation

DOI: 10.1038/s41439-026-00363-1