CGG REPEAT INTERRUPTIONS IN THE FMR1 GENE IN PATIENTS WITH INFANTILE-AUTISM

We determined the CGG repeat length and AGG interruptions in the FMR1 gene in normal Chinese subjects and patients with infantile autism and mild mental retardation. Genomic DNA was investigated by PCR and Sout hern hybridisation for CGG repeat number and PCR with Mnl I restrictio n analysis for AGG interruption. Both the normal subjects and the pati ents with autism have 53 CGG repeats in FMR I, and the majority have t wo interspersed AGG. Our normal Chinese subjects have a similar number of interspersed AGG as other populations. When compared with the norm al subjects, the autism patients have less AGG interruptions and a dif ferent pattern of AGG distribution. There was a significant difference in the CGG configurations between normal subjects and patients with a utism. The latter had less interspersed AGG, as in fragile X patients, but they did not have fragile X. A study on mentally retarded patient s with no infantile autism should also be carried out to ascertain whe ther mental retardation alone may have contributed to such AGG pattern .