Myotonic dystrophy is inherited in chromosomes -
Myotonic dystrophy is associated with a trinucleotide CTG repeat expansion on chromosome 9.
This expansion affects the mRNA for the dystrophila myotonia protein kinase (DMPK).

Myotonic dystrophy 

The characteristic feature of myotonic dystrophy is myotonia, i.e., the sustained involuntary contraction of a group of muscles.
Of all the dystrophies, only myotonic dystrophy shows pathological changes in the intrafusal fibres of the muscle spindles.
Extra-muscular abnormalities are : -


Cataract      
Frontal baldness
Gonadal atrophy        
DM
Dementia            
Decreased IgG
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