CKMT1B and obesity due to melanocortin 4 receptor deficiency: Transgenic mice depleted of CKB, CKMT1B, and GATM showed impaired creatine biosynthesis capacity affecting the murine body weight and resulting in a susceptibility to obesity (Streijger et al., 2005; Streijger et al., 2009; Kazak et al., 2017; Rahbani et al., 2021).