SHORT 4TH TOES IN RETT-SYNDROME - A BIOLOGICAL INDICATOR

Classic Rett syndrome is now well-known as a non-dysmorphic developmen tal disorder almost certainly of genetic origin. Short 4th toe (uni- o r bi-lateral) is inherited as an autosomal dominant with 27% penetranc e and is found also in certain dysmorphic syndromes. Having observed t he anomaly in several Rett cases, we examined a cohort of classic Rett people at advisory clinics and all the residents in an adult learning disabled hospital in order to determine the significance of the assoc iation. Among the Rett clinic group 28 of 137 showed the anomaly (20%) . Among the heterogeneous hospital group it was found in 19 of 526 peo ple, 9 of 206 females (4%) and 10 of 320 males (3%). Rett syndrome was present in 7% of all the The women (14 of 206 women). Four of the Ret t women show ed the toe anomaly (28% of the Rett cases). The anomaly w as found in 4 men and 4 nomen with Down syndrome, representing 16% (8 of 49). Diagnoses in other men with the anomaly included foetal alcoho l syndrome, toxoplasmosis. 18/2 translocation and birth injury. The on ly other woman with the anomaly tvas profoundly disabled with short li mbs. The strong positive association of the anomaly with, Rett syndrom e and Down syndrome throws new light on the developmental processes af fected by these diseases.