Objective        To make a genetic and clinical analysis in an autosomal dominant spinocerebellar ataxia (SCA) family combined with congenital atrial septal defect (ASD).       Methods        Family investigation

pedigree analysis and clinical diagnosis were performed on the 2 disease phenotypes respectively. Mutation detection of the disease genes associated with SCA and ASD by polymerase chain reaction (PCR) with direct DNA sequencing.       Results        There were 15 SCA familial patients of 4 generations

including 5 having dead. Both SCA and ASD were inherited in an autosomal dominant mode in this family. They presented walking instability

dysphagia and slurred speech after being 30 years old. Genetic diagnosis demonstrated the CAG repeat sizes of SCA3 causative gene were abnormally expanded. There were 5 ASD patients among these SCA patients

including the proband. Mutation screening of the ASD associated genes also revealed a coding mutation of MYH6 （c.1154CT） in the 3 ASD patients

which leading Ser385Leu. No such mutation was found in other family members.       Conclusion        There are 2 independent diseases in this family inherited as an autosomal dominant mode

which result from different pathogenic mutation of different disease genes.