ABSTRACT
Rett syndrome (RS) is one of the many mental retardation syndromes for which the genetic basis was recently identified. It is a neurodevelopmental disorder predominantly affecting females, associated with devastating loss of function between infancy and the fifth year of life. Thereafter, its course is relatively static, distinguishing it from most neurodegenerative disorders of childhood. Rett syndrome is pan-ethnic, affecting patients worldwide. The prevalence of the RS phenotype among females is estimated at 1:10,000-1:22,000, with 99.5% of all cases occurring in a sporadic manner. There are reports of males with molecular defects in the MeCP2 gene that present with a widely variable phenotype.
