LEP and vitamin D deficiency: Vitamin D insufficiency has also been linked to poor bone density,[30] however in our study our groups did not significantly differ.  Altered leptin levels have been found in both HD patients[31] and transgenic mice.[32]  One of leptin’s functions is to affect bone mass[33], [34] by inducing bone loss,[35] yet again we found no significant difference in leptin levels between study groups.