The DMPK protein is predominantly localized at sites of neuromuscular and myotendinous junctions of skeletal muscles. The largest encoded protein (isoform 1) is 639 amino acids in length and contains an N-terminal domain that shares strong homology to the cAMP-dependent serine-threonine protein kinase family. The dystrophia myotonica protein kinase gene (symbol DMPK, also identified as Mt-PK) is located on chromosome 19q13.32 spanning 13 kbp and and is composed of 15 exons that generate seven alternatively spliced mRNAs. Of note is that myotonic dystrophy is the first disorder in which the phenomenon of anticipation was demonstrated as the clinical basis of the course of the disease. Like many trinucleotide repeat disorders DM1 exhibits the genetic phenomena of anticipation which refers to the appearance of symptoms earlier and with increased severity in subsequent generations. Normal individuals have 5–37 repeats and affected individuals have repeats ranging from 50 to several thousand. The CTG repeat (CUG in the mRNA) resides in the 3′-untranslated region of the mRNA. Type 1 myotonic dystrophy is an autosomal dominant disorder resulting from the expansion of a CTG trinucleotide repeat in the dystrophia myotonica protein kinase gene (also called myotonin-protein kinase). Myotonic dystrophy is also referred to as Steinert disease. The disease manifests in nearly 1 in 8000 individuals. Type 1 myotonic dystrophy (originally abbreviated DM1 for the Latin dystrophia myotonica) is the most commonly occurring form of muscular dystrophy in adults. Clinical Features of Myotonic Dystrophy.Molecular Biology of Myotonic Dystrophy.

Dm1 disease