MT-RNR1 and obesity due to melanocortin 4 receptor deficiency: MOTS-c is also a mitochondrial-derived peptide that improves obesity and insulin resistance in mice (Lee et al. 2015), but the mechanism regarding translation of MOTS-c is not fully understood and requires further studies for understanding the natural course and tissue specificity of MOTS-c expression, as well as the metabolic effects of MOTS-c in humans.