The Association Of Rapsyn Gene Polymorphism With Myasthenia Gravis

Objective:Myasthenia gravis (MG) is an organ-specific autoimmune disease mediated by anti-acetylcholine receptor (AchR) autoantibody. Due to the variety of its couses the pathogenesis has not fully been understood yet. In this study, the gene mutations of receptor-associated protein at the synapse (rapsyn) were analysed to evaluate its association with severity of MG.Methods:The DNA was extracted from peripheral blood cells, sampled from33patients with MG and from51normal persons as control. The genes of exon3and exon5of rapsyn were amplified by PCR, sequenced and compared with wild-type rapsyn gene to identify the mutations and the frequency of each allele.Results:Compared with the wild-type gene sequences of exon3, a mutation of T to G was found both in patients and in normal persons, leading to the corresponding amino acid sequence at45L (leucine) into R (arginine). There were26cases of mutations in51normal persons. The allele T of the gene frequency was65.7%, and the allele G gene frequency was34.3%. Among the33cases of patient group, there were19cases of mutations and allele T of the gene frequency was66.7%, allele G gene frequency was33.3%. According to the statistical analysis we found that the mutation rate and allele frequencies between the normal group and patient group were not statistically significant. Compared with wild-type gene sequences of exon5, there was no point mutation in patients and normal persons. Through data analysis it was showed that this gene mutation in exon3might be a protective gene.Conclusion:The gene mutation (T to G) in exon3of rapsyn is a new one, which has not been reported yet, but is not the cause of the onset of MG. There is no correlation between exon5of rapsyn and the onset of MG since no mutation point in exon5has been found.