Ashizawa T, Dunne P W, Ward P A, Seltzer W K, Richards C S
Department of Neurology, Baylor College of Medicine, Houston, TX 77030.
Neurology. 1994 Jan;44(1):120-2. doi: 10.1212/wnl.44.1.120.
The mutation responsible for myotonic dystrophy (DM) is an unstable expansion of the CTG repeat within the myotonin protein kinase gene. To examine whether the parental origin of the expanded repeat influences the repeat size in offspring, we studied 51 father-child and 59 mother-child pairs with DM. Small expansions in fathers resulted in larger size expansions in their offspring, while large paternal expansions resulted in less size change in their offspring. However, there was no correlation between maternal size expansion and size increase in offspring for either congenital or noncongenital DM. These data suggest that the sex of the affected parent influences the unstable expansion of the repeat in DM offspring. While some evidence suggests that DNA methylation status cannot explain this observation, the mechanism for differential maternal/paternal transmission expansion is currently unknown.
导致强直性肌营养不良（DM）的突变是肌强直性蛋白激酶基因内CTG重复序列的不稳定扩增。为了研究扩增重复序列的亲本来源是否会影响后代的重复序列大小，我们研究了51对患DM的父子对和59对患DM的母子对。父亲的小扩增在其后代中导致更大的扩增，而父亲的大扩增在其后代中导致较小的大小变化。然而，对于先天性或非先天性DM，母亲的扩增大小与后代的大小增加之间均无相关性。这些数据表明，受影响亲本的性别会影响DM后代中重复序列的不稳定扩增。虽然一些证据表明DNA甲基化状态无法解释这一现象，但目前尚不清楚母体/父体传递差异扩增的机制。
