PPARA and obesity due to melanocortin 4 receptor deficiency: This metabolic dysfunction is associated with peroxisome proliferator-activated receptor (PPAR)-driven lipid accumulation in NK cells, and PPARα/δ target genes are highly up-regulated in obesity, which inhibits mTOR-mediated glycolysis as well as downstream transcription of cytotoxic particles and IFN-γ production.