SLC1A5 (ASCT2) deficits in intestinal epithelial cells impair antimicrobial peptide synthesis, worsening inflammatory bowel disease (IBD) (26, 27, 36), while reduced expression in psoriasis and obesity disrupts skin and T cell function (26, 33). The gene discussed is SLC1A5; the disease is obesity due to melanocortin 4 receptor deficiency.