Abstract：OBJECTIVE: To explore the chromosome karyotypes in children with mental retardation. METHODS: The peripheral blood lymphocytes from 92 chidren with congenital mental retardation were cultured and analysed by the G-band technique. RESULTS: Of the 92 cases, 43 cases (47%) showed chromosome abnormalities. Autosomal abnormalities were found in 35 cases (38%) and sex chromosome abnormalities were found in 8 cases (9%). A novel abnormal karyotype 45,XX,psu dic（11;9）（p15;p24）was found in a child. CONCLUSIONS: Chromosome abnormalities may be important cytogenetic factors for congenital mental retardation. Cytogenetic chromosome karyotypic analysis appears to be an important method for genetic screening of congenital mental retardation.
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