A193 DGAT1 DEFICIENCY WITHOUT DIARRHEA

Abstract Background Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) catalyzes the final step in triglyceride (TG) synthesis and is highly expressed enterocytes (EC). DGAT1 deficiency (DGAT1D) a rare autosomal recessive protein losing enteropathy (PLE) classified as congenital diarrheal disorder (CDD). Presumably, fat ingestion causes accumulation of substrates within EC causing lipotoxicity-induced dysfunction death. Aims Report presentation DGAT1D atypical for CDD. Methods We present an infant with protracted emesis failure to thrive (FTT) absence diarrhea despite enteral nutrition varied containing formulas (FCF). Results A male presented FTT requiring multiple admissions. He was initially diagnosed cow’s milk allergy due concurrent bloody stools, which resolved hypoallergenic formula. Reportedly watery stools when exclusively breastfed became formed following switch formula at 2 weeks age. Interestingly, he subsequently required intermittent suppositories. However, malnutrition progressed, refractory omeprazole, baclofen, hypo- non-allergenic FCF (all >0.02g/ml fat, mixtures medium long chain FA). had persistently low serum albumin, ceruloplasmin, IgG, but SA1AT normal. TGs were normal, although not measured on FCF. Low fecal elastase (FE) normalized after nutritional support sweat chloride intermediate. CFTR sequencing revealed mutations S466X R1070 cis. TPN started severe months. Emesis while fasted or receiving electrolyte solution. Endoscopic biopsies showed increased lamina propria cellularity, no villous abnormalities duodenum, chronic inflammation gastric body, normal colonic mucosa. Whole exome months homozygous c.838C>T (p.Arg280Ter) DGAT1, explaining his clinical biochemical features PLE. After diagnosis, Tolerex® (fat = 0.017g/ml), tolerated. Conclusions CDD, vomiting often reported. This case describes unique this condition, predominant symptom, notable constipation, demonstrating variable phenotype condition. Fat malabsorption may contribute constipation by altering viscosity luminal contents activating ileal brake. Thus, should be considered differential PLE, even without diarrhea. also demonstrates limitations stool testing random concentrations reflect A1AT clearance diagnosis FE has been detected children dietary restriction reported DGAT1D, where it likely represents physiologic consequence FTT. Funding Agencies None