ALMS1 and obesity due to melanocortin 4 receptor deficiency: Alms1GT/GT mice described by Collin et al. [15] harbor an insertion of a gene trap cassette in intron 13 of Alms1. On a mixed (C57BL/6J and 129P1/ReJ) genetic background, mice developed obesity, hyperinsulinemia, and hyperglycemia.