INS and obesity due to melanocortin 4 receptor deficiency: FAM13A in the region on chromosome 6 associated with adult August weight has been found to modulate body fat distribution and adipocyte function in humans and mice (Fathzadeh et al., 2020) affects adipose insulin signaling in mice (Wardhana et al., 2018) and is associated with obesity also in mice (Tang et al., 2019).