Two muscle diseases, megaconial congenital muscular dystrophy (MDCMC; OMIM #602541) and proximal myopathy with focal depletion of mitochondria (PMFDM; OMIM #600706), were recently shown to be allelic conditions caused by homozygous or compound heterozygous mutations in CHKB (encoding choline kinase β) [9]. This evidence concerns the gene CHKB and megaconial type congenital muscular dystrophy.