Diagnóstico y tamizaje del retardo mental hereditario más común, situación en Costa Rica.

fragile x syndrome (fraxa) is the most common type of hereditary mental retardation, and the second commonest with genetic origin. the range of affection in fraxa includes from learning problems to mental retardation. the syndrome includes speech and language deficits, abnormal behaviours, including autistic features, macro orchidism, prominent ears, hyperactivity, sensorial integration and motor impairments. actual data and the authors own work is reviewed. topics approached are the gene product, diagnostic methodology, clinical picture, epidemiology, prevention, screening and the actual situation in costa rica regarding this pathology.