Medical Definition of Dystrophia myotonica
1.
An inherited human neuromuscular disease classed as an autosomal dominant disease in which there is progressive muscle weakening and wasting.
A triplet repeat syndromes (like fragile X syndrome), this most common adult form of muscular dystrophy is caused by expansion of the unstable trinucleotide repeat CTG in the 3' untranslated region on chromosome 19q13 (cAMP-dependent muscle protein kinase gene).
Anticipation has been associated with further expansion of the repeat upon transmission to subsequent generations (the inheritance pattern is autosomal dominant), although contraction has been noted to occur as well. Especially severe neonatal cases have been born to affected mothers preferentially, suggesting a role for genomic imprinting as well.
The classic physical signs include atrophy of facial muscles, cataracts, and delayed muscle relaxation. Detection of the expanded trinucleotide repeat is accomplished by PCR or Southern blot and expansion appears to correlate with decreased transcription of the protein kinase gene.
Inheritance: autosomal dominant.
(29 Dec 1997)
Lexicographical Neighbors of Dystrophia Myotonica
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