The orthologs of Spn, protein phosphatase 1, regulatory subunit 9A (PPP1R9A) and protein phosphatase 1, regulatory subunit 9B (PPP1R9B), are associated with piglet birth weight [169] and pig food intake and human obesity [170]. The gene discussed is PPP1R9B; the disease is obesity due to melanocortin 4 receptor deficiency.