Objective: To investigate the influence of CAG trinucleotides repeat of some (CAG)n-containing gene and some gene polymorphisms in AO of SCA2, and analyse the difference of these gene polymorphisms between PD-SCA2 group and A-SCA2 group.

Background: Hereditary spinocerebellar ataxia type 2（SCA2）is one of the most prevalent autosomal dominant ataxias in china, with a high degree of clinical heterogeneity. Previous researches showed that age at onset (AO) of SCA2 is negatively correlated with the CAG trinucleotides repeat lengths in ATXN2 gene. However, the correlation can not fully explain the variation of AO and clinical symptoms between different patients.

Method: We obtained the DNA samples and clinical data from 75 autosomal dominant familial SAC2 patients which had alrealy been diagnosed by gene test, and 11 sporadic SCA2 patients. We determined the size of CAG repeat length in two allele of ATXN2 gene and the long-chain allele of ATXN1, ATXN3, CACNA1A, ATXN7, TBP, ATN1, IT15, HDL2, KCNN3 gene using polymerase chain reaction (PCR) amplification and capillary electrophoresis.

Results: There were no other genes associated with AO, except for the correlation between AO and CAG repeat lengths in the ATXN2 gene (r = -0.515, P = 0.000).

Conclusion: In conclusion, the CAG repeat lengths in ATXN2 gene is the main genetic factor, which could explain 40.8% of AO variance.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/research-on-the-modifier-gene-of-hereditary-spinocerebellar-ataxia-type-2/