Genetic Screening for Expanded FMR1 Alleles in a Moroccan Cohort With Unexplained Intellectual Disability

Abstract

ABSTRACT Background Intellectual disability (ID) constitutes a major neurodevelopmental disorder (NDD), arising from diverse genetic and environmental aetiologies. Fragile X syndrome (FXS), caused by CGG repeat expansion in the FMR1 gene, is one of the most common inherited causes of ID and autism. Aim In Morocco, FMR1 molecular screening data are currently not available. This study provides the first characterisation of FMR1 mutations in Moroccan patients with nonsyndromic ID (NS‐ID). Methods One hundred children and adolescents (75 boys and 25 girls) were tested using AmplideX PCR/CE FMR1 Kit based on fluorescent triplet‐primed PCR (TP‐PCR) and capillary electrophoresis (CE) to determine CGG repeat sizes. Results A total of 92% of individuals (23 females and 69 males) carried an FMR1 allele within the normal CGG repeat range (< 44 repeats), two of which were diagnosed with Klinefelter syndrome (KS). Two females (2%) presented intermediate alleles (45–54 repeats), both with 53 repeats. Six full‐mutation males (6%) were identified with CGG repeats > 200. Conclusion As the first molecular screening initiative targeting FXS in high‐risk patients, our results demonstrate the utility of testing in this population highlighting the importance of future multicentre studies.