中華民國小兒科醫學會第137屆學術演講會教育演講：先天性畸形－智障學童染色體篩檢及其追蹤研究

This report summarizes the cytogenetic screening results of 2,353 mentally retarded school children conducted in the past 15 years through three research projects. The first project (1977-1981) was aimed at identifying the chromosome abnormalities from the 470 mentally retarded patients. The incidence of chromosome abnormalities, ranged from 6.12% to 13.86%, was correlated with the severity of the mental retardation. The second project (1988-1990) was mainly a pilot study for establishing newborn screening method of metabolic diseases. The chromosome analysis was carried out as a by-product because of the availability of blood samples. Of the 1,323 patients examined, the incidence of chromosome abnormalities was also correlated with IQ, with 7.87% for IQ 50-75 and 17.51% for IQ less than 50. The third project (1989-1992) was designed for the detection of fragile X patients and their relatives for the purpose of molecular analysis of the FMR-1 gene expression. We found 18 patients with fragile sites at Xq27.3 and 65 patients (11.6%) with other chromosome abnormalities. A follow-up study and genetic counseling were carried out for three fragile X probands and their relatives. Dried blood samples on filter papers from a family of six with three fragile X boys were analyzed by RT-PCR method. The three male patients did not express any appreciable amounts of FMR-1 transcripts, while their parents and sister were positive for the FMR-1 specific band. This assay may be applied for the mass screening of fragile X patients from the mentally retarded populations.