MYMX and congenital myopathy with cores: We identified a homozygous truncating variant [c.107 T > A (p.Leu36Ter)] and a homozygous stop-codon loss variant [c.255 A > G (p.Ter85TrpextTer41)] in MYMX, both associated with a complex neuromuscular syndrome characterized by generalized hypotonia, congenital myopathy, facial nerve palsy, growth restriction and facial dysmorphism.