AIF1L and obesity due to melanocortin 4 receptor deficiency: These findings show that while AIF1L is not required for the pathogenesis of diet induced obesity and glucose insensitivity, its expression pattern in adipose tissues and brain and regulation of AIF1 expression in AIF1L KO mice suggest that this protein family may yet have a regulatory role in this context, and use of temporally-controlled or tissue specific KO models may uncover these anticipated functions.