We show that in serum CXM positively correlates to the bone biomarkers N-terminal propeptide of type I procollagen (P1NP, r = 0.50, p < 0.0001), C-terminal telopeptide of type I collagen (CTX, r = 0.40, p < 0.0001), and osteocalcin (r = 0.26, p = 0.0411); with a negative correlation to the obesity biomarker leptin (r = −0.31, p = 0.0138). The gene discussed is COL1A2; the disease is obesity due to melanocortin 4 receptor deficiency.