Experimental studies have shown that mice lacking CHRM3 (muscarinic acetylcholine receptor 3), the closest gene upstream of FMN2, are hypophagic and lean [24], and heterozygous knockout mice for BECN2 (beclin 2), a 2 Kb-long intronless gene located between EXO1 and MAP1LC3C (microtubule-associated protein 1 light chain 3 gamma), have elevated food intake, obesity and insulin resistance [25]. The gene discussed is CHRM3; the disease is obesity due to melanocortin 4 receptor deficiency.