This discrepancy between the numbers of expected and reported homozygotes/compound heterozygotes for c.1105 C>T may be due to several reasons, for example, (1) patients may die antenatally, (2) patients may have a phenotypically different disease, which does not resemble homocystinuria (such an example is the mutation p.V377I in mevalonate kinase gene22), (3) the disease manifests in an unrecognized mild adult-onset form, or (4) patients do not have any clinical symptoms at all. Here, MVK is linked to homocystinuria.