Chinese J Med. Genet.
13:131, 1996.Shanghai Institute of Medical Genetics, Shanghai Children's Hospital, China.
This is a study on the pathogenesis of Huntington’s disease (HD), The polymorphic CAG repeats in the IT15 gene in normal Chinese and HD patients were determined with nested PCR, denaturing polyacrylamide gel electrophoresis and direct sequencing analysis. A total of 40 normal individuals and 122 members of 13 unrelated HD families from different provinces in China were included in this study. The results showed that the (CAG)n repeat numbers in 270 normal alleles ranged from 13 to 26, mostly 16 in number, while in 54HD alleles, the number of CAG repeats was from 40 to 94, with an unstable inheritance of expanded repeats in some families. There was no overlap between the copy number of the normal and affected alleles. In addition, the presymptomatic diagnosis 103 family members at risk for HD disclosed that 35 individuals had HD alleles. These findings suggest that the unstable mutation in IT15 gene be responsible for the genetic defect in Chinese HD patients and a correlation should exist between the number of (CAG)n repeats and the onset age of the disease.