Clinical And Genetic Characteristics Of Spinal Cerebellar Ataxia Type 3

Objective:Screening of pathogenic genes in the family of Spinocerebellar ataxia(SCA)was conducted to investigate the Clinical and genetic characteristics of SCA.Methods: according to the Harding standard,2 families clinically diagnosed as SCA were collected,the clinical and genetic manifestation of the patients were summarized,and the standard genealogy was constructed.A total of 11 family members were select-ed.Sequence the number of CAG trinucleotide repeats of ATXN3 gene by PCR and calculate the number of CAG repeats,to make the gene diagnosis.Results:.Family 1: SCA3 families were diagnosed by sequencing results,There were 70 times CAG amplifications in ? 3,The ATXN3 product of ? 5 sequencing results show(the CAG)n amplification for 70 times,The ATXN3 product of IV6 sequencing results display(the CAG)n amplification for 69 times,the normal family members without clinical symptoms(? 2 IV4 IV5)repetitions for 8 times.The iv7 without family genetic history was 26 times.Family 2: genetic testing results:(There are two amplified fragments of atxn3 gene of proband ? 3.Small(236bp)(CAG)n repeats about 16 times,within the normal range,and the number of large(426bp)(CAG)n repeats is about 79 times.The repetitions of ? 4,? 1 and ? 2 were26,24 and 24 times respectively.Conclusions: 1.The first clinical symptom of SCA3 patients is unstable walking,Mu-scle tremor is widespread and investigated in two family patients,Eye tremor is a non-ataxia symptom that cannot be ignored in patients with SCA3.2.The pathogenic gene in this family was ATXN3,The normal CAG repeats were 8-26 times and the pathoge nic CAG repeats were 69-79 times in the families investigated.This study enriches th e number of normal CAG repeats.3.SCA3 has clinical heterogeneity,clinical features can guide genetic screening,and genetic testing is a unique measure to distinguish gen-otypes.