The cellular source of both TRAIL and sTRAIL as well as sTRAIL secretion mechanisms are not fully understood and it is unclear whether the observed direct correlation of TRAIL concentration with obesity reflects increased synthesis and/or increased adipocyte release or is a consequence of the activation of other biological pathways by adipose tissue [21]. The gene discussed is TNFSF10; the disease is obesity due to melanocortin 4 receptor deficiency.