[Myotonic dystrophy and myotonin kinase protein gene mutation].

Myotonic dystrophy (DM) is an autosomal dominant defect associated with an underlying CTG trinucleotide repeat expansion of the myotonin protein kinase (MTPK) gene at a locus on chromosome 19 (19q13.3). The triplet repeat expansions occur in 3'non-coding regions of MTPK genes, CTG repeat expansions predetermine the clinical severity and the age at which the disease occurs: the larger the expansions, the higher the probability of congenital DM transmission, as a rule, by maternal line. The gene's product--myotonin protein kinase--has Mr 62 and/or 53kD and is mainly found in the striated muscles and in the myocardium. The enzyme is of serin threonin kinase character. Its participation in the initiation and progress of the disease has not yet been clarified up. (Ref. 63.).