(C) Aligned DNA and amino acid sequences of MYH3 and smyhc1 alleles surrounding the smyhc1R673H and MYH3 R672H substitutions. The smyhc1- allele has a 7 base pair deletion that results in a frameshift in which one errant amino acid precedes a premature stop codon. The smyhc1R673H allele results from a G>A transition single point mutation. 