Rett syndrome: photographic evidence of rapid regression.

Rett Syndrome is known to occur in females, around the second year, with loss of hand use, onset of stereotypes and acquired microcephaly. Such regression is often very rapid, but this has never been documented. In one of our patients, photographs taken at different times clearly demonstrate the rapid progression of first symptoms. Moreover, in the present case, the occurrence of a febrile illness, which preceded the onset of the neurological picture, support the hypothesis that environmental factors may trigger the onset of Rett Syndrome in genetically predisposed subjects.