SLC25A33 and obesity due to melanocortin 4 receptor deficiency: The latter enzyme (PolyNic) has also higher catalytic efficiency than the Saccharomyces cerevisiae PNC1 nicotinamidase (French et al., 2010b), which is the most used nicotinamidase in enzyme-coupled assays for identifying new sirtuin modulators (Hubbard and Sinclair, 2013) as possible pharmaceuticals in lifespan, cancer, obesity and neurodegenerative diseases.