The Rett and Rett-like syndromes: a broad concept.

Eight patients who satisfied the following three criteria: 1) autistic behavior, 2) mental retardation and 3) stereotypic hand movements were evaluated. Four patients fulfilled the diagnostic criteria for the Rett syndrome developed by representatives of the International Rett Syndrome Association and the Center for Disease Control, Atlanta, USA. The other four Rett-like patients were atypical in the sense that the manifestations were incomplete or psychomotor development throughout the first 6 months of life was abnormal or the disease was heralded by infantile spasms with transient stereotypic hand movements or the baby was born with congenital microcephaly. All eight patients were girls. No laboratory test result specific for the Rett syndrome or Rett-like syndrome was obtained.