TBX15 and obesity due to melanocortin 4 receptor deficiency: For some targets, including Tbx15, the associations appeared specific for skeletal muscle expression and were not detected in either adipose or liver tissue, suggesting a muscle-specific role of Tbx15. This is consistent with the earlier finding that Tbx15 regulates muscle metabolism in mice and Tbx15 knockout animals are resistant to diet induced obesity and impaired glucose tolerance55.