[Genetic and clinical analysis in a Parkinson's disease family caused by expansion of SCA2].

To analyze the clinical and genetic features of a family with Parkinson's disease caused by expansion of CAG triplet repeat in the ATXN2 gene.The CAG/CAA repeat in the ATXN2 gene was analyzed by polymerase chain reaction (PCR) and Sanger sequencing.Molecular testing has documented a pathological heterozygous expansion of the CAG repeat from 33 to 35 in 6 patients and other 8 family members. Two patients had pure CAG triplet repeat expansion in their ATXN2 gene, while others had CAA interruption.Expanded CAG/CAA repeat in the ATXN2 gene is the causative mutation of the disease in this family.The 8 members with expanded CAG/CAA repeat may be asymptomatic patients. It is supposed that the number and configuration of the ATXN2 CAG/CAA repeat expansion may play an important role in the phenotypic variability of Parkinson's disease.