This raises the possibility that the selection of particular nutrients may not only lead to obesity, but also reduce oxygen demand and thus ventilatory supply, which could in turn lead to sleep-disordered breathing and pulmonary hypertension, in a manner exacerbated through consequent changes in cell-specific expression of AMPK subunit isoforms. The gene discussed is PRKAA1; the disease is obesity due to melanocortin 4 receptor deficiency.