VDR and obesity due to melanocortin 4 receptor deficiency: Table 3 also shows that VDR variants Cdx2 (GG) and possibly Tru91 (Uu) interacted with dietary vitamin D to modify BMI, while VDR-Fok1 was significantly associated with BMI independent of dietary vitamin D. This, and the relationship with insulin described above for the Taq1, Apa1 and Bsm1 variants is consistent with published data suggesting a link between vitamin D status altered insulin synthesis and secretion [3] and an association with obesity [4].