Jansen G, Bartolomei M, Kalscheuer V, Merkx G, Wormskamp N, Mariman E, Smeets D, Ropers H H, Wieringa B
Department of Cell Biology and Histology, Medical School University Nijmegen, The Netherlands.
Hum Mol Genet. 1993 Aug;2(8):1221-7. doi: 10.1093/hmg/2.8.1221.
To explain the restriction of early onset cases of myotonic dystrophy (DM) to maternal transmittance and the significant excess of male transmitters in the last asymptomatic generation, the involvement of parental effects on the autosomal dominant mode of inheritance has been suggested. Using FISH we confirmed that the DM-kinase gene is proximal to the ApoE gene on mouse chromosome 7, close to an imprinted segment. To study whether there is any firm molecular basis for the speculation that imprinting may be involved in DM we have analysed the expression of paternal and maternal alleles of the DM-kinase gene in human and mouse tissues. Length polymorphisms in the 3' non coding exons of human and mouse DM kinase genes, i.e. the variable [CTG]n repeat motif in humans and a newly identified Cn stretch variation in mice, served as tools to distinguish between allelic RNA products in various tissues. In human tissues, presence of transcripts from both parental alleles could be demonstrated by RT-PCR. In mouse, similar observations were made using a RNAse protection assay on fetal and adult muscle RNAs. We conclude that imprinting does not play a role in the expression of the DM kinase gene.
为了解释强直性肌营养不良（DM）早发病例仅限于母系遗传以及在最后一个无症状世代中男性传递者显著过多的现象，有人提出亲本效应参与常染色体显性遗传模式。我们运用荧光原位杂交技术（FISH）证实，DM激酶基因在小鼠7号染色体上靠近载脂蛋白E（ApoE）基因，临近一个印记区段。为研究印记可能与DM有关这一推测是否有确凿的分子基础，我们分析了人及小鼠组织中DM激酶基因父本和母本等位基因的表达情况。人和小鼠DM激酶基因3'非编码外显子中的长度多态性，即人类中可变的[CTG]n重复基序以及小鼠中新发现的Cn序列变异，被用作区分不同组织中等位基因RNA产物的工具。在人体组织中，通过逆转录聚合酶链反应（RT-PCR）可以证明两个亲本等位基因的转录本均存在。在小鼠中，利用对胎儿和成年肌肉RNA的核糖核酸酶保护分析也得到了类似的结果。我们得出结论，印记在DM激酶基因的表达中不起作用。
