Abbruzzese C, Krahe R, Liguori M, Tessarolo D, Siciliano M J, Ashizawa T, Giacanelli M
San Camillo Hospital, Rome, Italy.
J Neurol. 1996 Oct;243(10):715-21. doi: 10.1007/BF00873977.
Myotonic dystrophy (DM) is associated with an expansion of an unstable (CTG)n repeat in the 3' untranslated region of the DM protein kinase (DMPK) gene on chromosome 19q13.3. We studied six patients from two families who showed no expansions of the repeat, in spite of their clinical diagnosis of DM. These patients had multi-systemic manifestations that were distinguishable from those seen in other myotonic disorders, including proximal myotonic myopathy (PROMM). In one additional family, two symptomatic members showed no expanded (CTG)n repeats, while their affected relatives had the expanded repeats. DM haplotype analysis failed to exclude the DMPK locus as a possible site of mutation in each family; however, DMPK mRNA levels were normal. We conclude that a mutation(s) other than the expanded (CTG)n repeat can cause the DM phenotype. The mutation(s) in these families remain(s) to be mapped and characterized.
强直性肌营养不良（DM）与位于19号染色体长臂13.3区的强直性肌营养不良蛋白激酶（DMPK）基因3'非翻译区不稳定的（CTG）n重复序列扩增有关。我们研究了来自两个家系的6名患者，尽管他们临床诊断为DM，但重复序列并未扩增。这些患者有多系统表现，与其他强直性肌病（包括近端强直性肌病，PROMM）所见的表现不同。在另一个家系中，两名有症状的成员未出现（CTG）n重复序列扩增，而他们受影响的亲属有扩增的重复序列。DM单倍型分析未能排除DMPK基因座作为每个家系中可能的突变位点；然而，DMPK mRNA水平正常。我们得出结论，除了扩增的（CTG）n重复序列外，其他突变也可导致DM表型。这些家系中的突变仍有待定位和鉴定。
