This variation is caused not by compound heterozygosity, but rather by the fact that several different enzyme defects can cause the disease. Clinically, most cases of hemochromatosis are found in homozygotes for the most common mutation in the HFE gene. But at each gene locus associated with the disease, there is the possibility of compound heterozygosity, often caused by inheritance of two unrelated alleles, of which one is a common or classic mutation, while the other is a rare or even novel one.
This variation arises not from compound heterozygosity, but rather due to the presence of multiple enzyme defects that can cause the disease. Clinically, most cases of hemochromatosis are found in individuals who are homozygous for the most common mutation in the HFE gene. However, at each gene locus associated with the disease, there is the possibility of compound heterozygosity, often caused by inheriting two unrelated alleles, one of which is a common or classic mutation, while the other is a rare or novel one.