Assiocation Between CAG Repeat Length And Age At Onset Of Spinocerebellar Ataxia Type 3:A Meta-Analysis

Objective To explore the association of CAG repeat length and age at onset of spinocerebellar ataxia type 3 by meta-nanlysis.Methods Data were collected from the following electronic databases:Pubmed,Excerpta Medica Database(Embase),Medline,ISI Web of Science,Chinese Biomedical Literature Database(CBM),China Academic Joumal database(CNKI),VIP,Wanfang,with the last report up to December 31,2017,in order to collect literatures on the correlation between CAG repeat length and age at onset of spinocerebellar ataxia type 3.The studies were screened according to the inclusion and exclusion criteria,after extracting data and assessing the quality of the included studies.All the meta analysis in this study was carried out by R sofhtwore(Version 3.4.3).Results A total of twelve studys were included in the meta analysis.The total sample amounts were 411 subjects.The results of Meta-analyses showed that merge correlation coefficient of CAG repeat length and age at onset of spinocerebellar ataxia type 3,and 95%cofidence interval(CI)were-0.9952(-1.10;-0.90).In the subgroup analysis,we found that the merge correlation coefficient of CAG repeat length and age at onset of spinocerebellar ataxia type 3 were reduced with the samples amounts increase,which of with the increase of years,the merge correlation coefficient decreased,the correlation coefficient mearsured by ethnicity was different.Moreover,we detect ethnicity could explain the source of heterogeneous,and there is no publication bias in the meta analysis.Conclusions(1)There is a strong negative correlation between the CAG repeat length and the age at onset of spinocerebellar ataxia type 3,the longer CAG repeat length,the younger the age at onset of the spinocereal ataxia type 3,the shorter CAG repeat length,the older the age at onset of the spinocereal ataxia type 3.(2)The repeat length of CAG accounted for 40.6%of the age at onset of the spinocereal ataxia type 3.Racial differences has an effect on the age at onset of the spinocereal ataxia type 3.