Giordano M, De Angelis M S, Cantello R, Abdirisak N A, Mutani R, Momigliano Richiardi P
Dipartimento di Scienze Mediche, Università di Torino, Italy.
Clin Genet. 1995 Jun;47(6):302-4. doi: 10.1111/j.1399-0004.1995.tb03969.x.
The number of copies of CTG trinucleotide repeats in the myotonic dystrophy gene correlates to a certain degree with the clinical symptoms in the patient. Routine molecular analysis of myotonic dystrophy is performed on peripheral blood cells detecting the size of the expansion in leukocytes. However, in some cases somatic mosaicism is responsible for the presence of differently sized myotonic dystrophy alleles in different tissues of the same affected individual, complicating diagnosis and prognosis. Here we report two cases in which the correlation between molecular and clinical analysis performed with standard procedures posed some interpretative problems. The first individual was affected by an atypical clinical picture of myotonic dystrophy, the severity of which was not correlated with the low number of triplet repeats detected in his leukocyte DNA. The second case illustrates a prognostic problem in the presence of a low degree expansion in leukocytes. These examples outline the limits of standard molecular and clinical analysis in myotonic dystrophy.
强直性肌营养不良基因中CTG三核苷酸重复序列的拷贝数在一定程度上与患者的临床症状相关。强直性肌营养不良的常规分子分析是在外周血细胞上进行的，检测白细胞中扩增片段的大小。然而，在某些情况下，体细胞镶嵌现象导致同一受影响个体的不同组织中存在大小不同的强直性肌营养不良等位基因，这使得诊断和预后变得复杂。在此，我们报告两例病例，其中采用标准程序进行的分子分析与临床分析之间的相关性存在一些解释问题。第一个个体患有强直性肌营养不良的非典型临床表现，其严重程度与在他的白细胞DNA中检测到的低三联体重复次数不相关。第二个病例说明了白细胞中低程度扩增情况下的预后问题。这些例子概述了强直性肌营养不良标准分子分析和临床分析的局限性。
