Molecular cytogenetic study of the myotonic dystrophy by in situ hybrdization (ISH)

强直性肌营养不良症(DM)是一种常染色体显性遗传病，其致病基因编码DM蛋白激酶(DMPK)，位于染色体19q13。虽然DM是由DMPK基因3‘端非编码区三联体(CTG)重复序列的异常扩增所致，但其发病的分子机制尚不清楚。本研究采用原位杂交(ISH)方法对DM的分子发病机制进行了研究，结果表明：(1)DMPK等位基因突变的转录本聚集在患者LCL的细胞核内；(2)累积的转录本主要是来自突变等位基因的mRNA，而不是前-mRNA。此外，通过分子生物学研究发现，患者细胞核中的mRNA量明显高于正常人，这支持了上述ISH方法的结果。由于从突变等位基因转录的加工后的miRNA在患者的细胞核中积聚，这可能为研究具有不同临床特征的患者的发病机制提供关键，我们将进一步研究以解决这一问题。

Myotonic dystrophy (DM) is an autosomal dominant disease, whose responsible gene encodes DM protein kinase (DMPK) and is located on the chromosome 19q 13. Though DM is caused by abnormal expansion of triplet (CTG) repeat at 3'UTR of DMPK gene, the molecular mechanism of the causing disease have been still unknown.In this study, we have gained the following results by using in situ hybridization (ISH) method to search the molecular pathogenesis of DM.It shows that (1) DMPK transcripts from mutant allele were accumulated in the nuclei of the LCL obtained from the patients, (2) the accumulated transcripts were mainly mRNA rather than pre-mRNA from mutant allele. Moreover, the amount of mRNA in the nuclei of the patients was found to be significantly higher than those in the nuclei of the normal individuals by the molecular biological study, which supports the result by ISH method described above.As the result that the processed mIRNA transcribed from mutant allele are accumulated in the nuclei of the patients may provide a key point to study the pathogenesis of the patients with various clinical features, we will make a further study to resolve the problem.