Those included 30 confirmed heterozygous carriers of the TNNI3 p.Arg21Cys mutation and 27 subjects with clinical evidence of HCM—including 22 with SCD in the context of no known medical history—who are implied to have inherited the p.Arg21Cys mutation based on their phenotype and pedigree relationship to a first-degree p.Arg21Cys carrier (Figure 1; Table). The gene discussed is TNNI3; the disease is Schnyder corneal dystrophy.