TRAPPC9 and obesity due to melanocortin 4 receptor deficiency: As maternal Trappc9 knock-out mice (Trappc9m-/p+) retain 30% brain Trappc9 expression versus 70% in paternal Trappc9 knock-out mice (Trappc9m-/p+) mice (Fig 3C), the obesity phenotype positively correlates with the degree of Trappc9 depletion and therefore with Trappc9 allelic-biased expression in the brain.