[Rett syndrome a developmental disorder. Presentation of a variant with preserved speech]

Rett's syndrome is a disorder of neuropsychological development of unknown aetiology. All those described as having all the classical traits of the syndrome are girls. Typically apparently normal development in the first year of life is followed by loss of acquired hand skills and speech, together with deceleration in the growth of the head and development of characteristic hand washing movements, hyperventilation and mental retardation. The disorder is the most common cause of progressive mental retardation in girls. Parents experience health workers who have not heard about this disorder. The article describes a four year-old girl with some preserved speech and an ability to sing. This is an atypical trait in a variant of Rett's syndrome. The importance of cooperation between different professions and medical specialties is underlined. Early diagnosis and start of intervention may delay loss of function. Controlled clinical trials, both medical and psychological, are needed.