rs397515963(C;C)

One dominant pathogenic mutation is bad. Two is considered to be worse. One recorded case of a child born with homozygosity for the c.2373dup variant resulted in cardiomegaly and death at 12 weeks. In contrast to heterozygous pathogenic mutations, homozygous or compound heterozygous truncating pathogenic MYBPC3 mutations cause severe neonatal cardiomyopathy with features of left ventricular noncompaction and septal defects in approximately 60% of patients.