Dynamic mutation analysis of a SCA3 Chinese Han family and prenatal diagnosis

Abstract

Objective To explore the clinical features, genetic characters and the importance of prenatal diagnosis in spinocerebellar ataxia 3 (SCA3) patients. Methods SCA3/ATXN3 gene was determined by using PCR and segmental analysis techniques in 2 patients among a SCA3 Chinese Han family which included 9 patients in four generations. One patient was the proband's fetus. The clinical characters were also documented and analyzed in this family. Results There were 9 patients in this family with autosomal dominant inheritance feature. The initial symptoms in all affected members except the fetus were the gait disorders accompanied by dysphasia. Inability of upward gaze and bilateral Barbinski's signs were noted in proband. The onset age became earlier from generation to generation in this family which was around 50 year⁃old, 40 to 45 year⁃old, 28 year⁃old in generation Ⅰ, Ⅱ and Ⅲ, respectively. CAG repeats in SCA3/ATXN3 allele were 77 in proband, as well as in the fetus, while the normal SCA3/ATXN3 allele CAG repeats were less than 44. Conclusion SCA3 is the most frequent subtype of SCA in Asian. Unsteadiness of gait are first noted in most patients accompanied by other different symptoms and signs. Genetic anticipation was found in SCA3. But gene analysis revealed less dynamic mutation frequence in this family. Since there was no effective treatment in SCA3, hereditary consultation and prenatal diagnosis play an important role in disease prevention and hereditary. DOI：10.3969/j.issn.1672⁃6731.2012.03.010

Keywords

• Spinocerebellar ataxias
• Trinucleotide repeat expansion
• Genetic counseling consultation
• Prenatal diagnosis