Autosomal dominant MyHC IIa myopathy, was originally identified as a muscle disorder in western Sweden. The disease was caused by a heterozygous missense mutation in MYH2 encoding MyHC IIa. The mutation changes the highly conserved and negatively charged glutamate at position 706 to the positively charged lysine (E706K). The mutated residue is located in the SH1 helix in the core of motor domain, which is highly conserved through evolution.
A prenatal onset of the disease was indicated by multiple joint contractures that were present at birth in the majority of the patients.
The clinical picture in patients with recessive MYH2 mutation was surprisingly mild with minor or moderate generalized muscle weakness.
MYH2