Furthermore, the metabolic phenotype observed in the CerS5 global knockout by Gosejacob et al., are in direct contrast to those from Hammerschmidt et al., where it was reported that CerS6, but not CerS5, was necessary for obesity-driven insulin resistance and mitochondrial dysfunction (17, 22). This evidence concerns the gene CERS6 and obesity due to melanocortin 4 receptor deficiency.