Rett syndrome: epidemiology and nosology--progress in knowledge 1986--a conference communication.

Recent progress from pooled clinical experience is reviewed. The approximate number of documented cases of Rett syndrome (RS) as of October 1986 was 1,100. Three sister pairs, 3 monozygotic twin pairs (both twin girls affected), 3 dizygotic twin pairs (one twin girl affected) are known. Genetics are discussed based on these and other known occurrences. Early seizure-onset variants have been reported in a dozen cases representing various countries. Approximately 20 incomplete RS related cases, also termed "formes frustes," are documented as of October 1986. An actual Swedish series of 66 classical RS, 4 "formes frustes," 2 early seizure-onset variants and 9 other clinically near related atypical cases is summarized. A suggested late stage IV spinal cord impairment is discussed, as well as the whole adult multifacetted complex neurological pattern. Gastrointestinal pathology is discussed with reference to possible generalized neuropeptide disturbances.