OBJECTIVERett syndrome (RTT) is a neurodevelopmental disorder which causes severe mental retardation. This study aimed at elucidating clinical features of 66 Chinese RTT cases diagnosed by The Department of Pediatric Neurology, Peking University First Hospital since 1987, and at analysis of the MeCP2 genotype / phenotype correlation.

METHODSSixty-six RTT cases were followed up every one to two years to get the information of their clinical manifestations and the response to the L-carnitine treatment which was administered to the patients at a dose of 80-100 mg/(kg d). MeCP2 mutation analysis by PCR and sequencing were performed on 39 cases.

RESULTSIn this cohort of cases, the onset of the disease occurred between 3 and 38 months of age, 89% of the cases lost their purposeful hand use at 7 months to six years of age, all the cases had stereotype hand movement which presented at 1 to 5 years of age, 85% of the cases lost language ability at 11 months to eight years of age, 21% of the cases lost the ability of walking at ages of 2 years and 9 months to 15 years. The symptoms/signs such as small head circumference, seizures, breathing irregularities, teeth grinding, scoliosis/ kyphosis were presented in many of the cases. The clinical manifestations were improved in 6 cases after L-carnitine treatment. MeCP2 gene mutation was found in 64% of the cases. Two cases with non-sense mutation C502t (amino acid change R168X) died, two cases with missense mutation C397T (amino acid change R133C) and one case with missense mutation A398T (amino acid change R133H) preserved several words.

CONCLUSIONDeceleration of the head growth, loss of acquired purposeful hand use, stereotype hand movement and language deterioration were the main characteristics of RTT. L-carnitine could improve the clinical manifestation of some cases. There are some correlations between MeCP2 genotype and phenotype.