Diacylglycerol O ‐Acyltransferase 1 Deficiency in Children: A Systematic Review

AIMS: Diacylglycerol O-acyltransferase 1 (DGAT1) deficiency is a rare autosomal recessive congenital diarrhoeal disorder caused by impaired intestinal triglyceride synthesis, leading to early-onset gastrointestinal disease, protein-losing enteropathy (PLE), and nutritional complications. This systematic review aimed to characterise the clinical, genetic, diagnostic, therapeutic, and outcome spectrum of DGAT1 deficiency in children. METHODS: A systematic review was conducted in accordance with PRISMA 2020 guidelines. PubMed, Embase, Scopus, Web of Science, and the Cochrane Library were searched from inception to 20 October 2025. Studies reporting genetically confirmed DGAT1 deficiency in children were included, and demographic, genetic, clinical, laboratory, treatment, and outcome data were synthesised. RESULTS: Twenty-two studies comprising 66 children were included. Chronic diarrhoea was reported in 58 children (87.9%), growth faltering in 44 (66.7%), vomiting in 40 (60.6%), and PLE in 46 (69.7%). Disease onset occurred predominantly during the neonatal period or early infancy. Parenteral nutrition was administered to 52 children (78.8%), while fat-restricted dietary therapy was explicitly reported in 44 (66.7%). Clinical improvement was documented in 56 children (84.8%), and growth improvement in 44 (66.7%). Survival status was available for 54 children; 10 of 66 children (15.2%) died, mainly from severe infectious complications. CONCLUSIONS: DGAT1 deficiency should be considered in children with early-onset diarrhoea or vomiting accompanied by PLE, hypoalbuminaemia, and growth faltering. Early molecular diagnosis and individualised fat-restricted nutritional therapy are central to management and are associated with substantial clinical improvement, although severe infantile disease remains associated with important morbidity and mortality.