The fragile X syndrome: 13 years of experience

Fragile X syndrome (FXS; MIM #300624; FRAXA, Xq27.3) is well known and a common cause of X-linked mental retardation. The syndrome is caused by dynamic mutation of FMR1 gene CpG island CGG repeats. Clinically FXS patients demonstrate delayed developmental milestones, particularly speech, attention-deficit/hyperactivity disorder, autistic features, and psychomotor development delay. Dysmorphic face and macroorchidism are important features in the postpubertal age. We present our 13-year experience with FXS patients who were confirmed by molecular diagnostic. Phenotype-genotype evaluation was made for 12 male FXS patients. Genotype-phenotype analysis did not reveal significant correlation between clinical symptoms observed in FXS patients and genotypes obtained from leucocytes DNA analysis. The prevalence of the fragile X syndrome in the Latvian male population was estimated to be 1/6428 (95% CI 5538-7552) or 15.55/100 000 males (95% CI 13.24 - 18.05). The prevalence of the fragile X syndrome among mentally retarded male patients was estimated to be 2.67%. The low number of diagnosed patients with fragile X syndrome demonstrated in our study led to the conclusion that fragile X syndrome is generally clinically unrecognised.