GRIN2A and obesity due to melanocortin 4 receptor deficiency: Furthermore, another gene, GRIN2A, that is part of the family of genes {GRIN1, GRIN2A, GRIN2B, GRIN2C, GRIN2D, GRIN3A, and GRIN3B}, which encode proteins that form a receptor in charge of sending chemical messages between neurons in the brain, was found to be associated to obesity in adult women defined as metabolically healthy in Schlauch et.