In contrast, we found that none of the six variant genotypes of DHCR7/NADSYN1 was associated with serum 25(OH)D levels in any of the three population groups that were studied, suggesting minimal involvement of these SNPs or the DHCR7/NADSYN1 gene in mediating vitamin D insufficiency in these populations. The gene discussed is NADSYN1; the disease is vitamin D deficiency.