[Developmental disorder in girls due to Rett syndrome].

Three girls with Rett syndrome are presented. Patients A and B had initially exhibited normal development, patient C showed severe developmental delay from birth on. In all three stereotypical hand movements arose which led to Rett syndrome being suspected. For patients A and B the clinical diagnosis was further supported by the identification of mutations in the MECP2-gene. In patient C, the mutation found turned out to be a neutral variant. Rett syndrome is a X-linked developmental disorder, which is particularly prevalent in girls. In 70-90% of clinically diagnosed RS patients a mutation is detected. MECP2-mutations result in a far wider range of phenotypes than classic RS. Mutations of this gene also occur in boys, with or without Rett-syndrome type phenotypes.