Neuropsychological disorders in fragile X syndrome

Fragile X syndrome is a hereditary disease that ranks second in frequency after Down syndrome among hereditary forms of mental retardation in boys. It is caused by the expansion of trinucleotide repeats «cytosine- guanine-guanine» in the promoter region of the FMR1 gene. Its somatic phenotypic features are: an elongated face with a high forehead and large protruding ears, hypermobility of the joints and macroorchidism that occurs in adolescence. The behavioral phenotype for this disease is represented by a combination of neuropsychological syndromes of mental retardation of varying severity, autism and attention deficit hyperactivity. Manual stereotypes, increasing with age, complement the clinical picture. These somatic and behavioral phenotypes make it possible to suspect the syndrome of fragile X chromosome. However, a specific molecular genetic study is required to confirm the diagnosis.