The epidemiology and public health significance of Rett syndrome.

Current data indicate that Rett syndrome is an important contributor to the total burden of idiopathic mental retardation. Studies from Sweden suggest that among girls the prevalence of Rett syndrome may be twice the prevalence of phenylketonuria. Successful epidemiologic studies of idiopathic mental retardation syndromes will require both large sample sizes and homogeneous populations. Because Rett syndrome is a relatively homogeneous and common syndrome of idiopathic mental retardation, epidemiologic methods may be more productive in the study of Rett syndrome than in other syndromes of mental retardation that are less clinically homogeneous. The approaches used in studying Rett syndrome epidemiologically may later be useful in the study of other syndromes of idiopathic mental retardation.