Clinical and Molecular Genetic Characterization of a Female with Fragile X Syndrome and Two Expanded Alleles: A Case Report

Fragile X syndrome is a genetic condition causing a range of developmental problems, with males more severely affected compared to female patients. The main features include a long and narrow face, large ears, and a prominent jaw and forehead. Males develop enlarged testicles after puberty, and carrier females are expected to show fragile X-associated primary ovarian insufficiency (FXPOI). Fragile X Syndrome (FXS) was suspected in a consanguineous family referred to a Medical Genetics center because of a family history of intellectual disability and primary ovarian insufficiency in their small village population. The cytosine guanine guanine (CGG) repeat expansion of the FMR1 gene in the 65-year-old proband was amplified and then analyzed by Gene Marker software. The female proband showed two expanded alleles, including one full mutation allele and one premutation allele with an accurate size of 74 (CGG) repeats. Despite having two mutant FMR1 alleles and manifesting some symptoms of FXS, she was fertile. Consanguineous marriages and, in more unfavorable conditions, marrying Fragile X-affected or premutation-carrying males with female carriers is not uncommon in such genetically isolated populations. Therefore, the need for Fragile X syndrome examination in suspected patients with similar features and screening their relatives is highly emphasized.