MYH1 and congenital myopathy: Candidate genes for congenital myopathies have a significant overlap with genes proposed for muscular dystrophies, for example for TMOD1 and TNNI1. Among those with a high rank in congenital myopathies are RYR3 and MYH1. RYR3 codes for a ryanodine calcium release channel with a low Ca2+ sensitivity that has a physiologic role in the excitation-contraction coupling of neonatal skeletal muscles and is up regulated in steroid-associated muscle damage [34], while MYH1 is one of the adult skeletal muscle isoforms of myosin heavy chain that predominates in 2B myofibers.