Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion

gene, which encodes the enzyme LAL. LAL is essential for the metabolism of cholesteryl esters and triglycerides. LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes but excluding the central nervous system. Infants with rapidly progressive LAL-D present with gastrointestinal disturbance, adrenomegaly with calcification, hepatosplenomegaly, growth failure due to malabsorption, and systemic inflammation. If untreated, rapidly progressive LAL-D typically leads to death within the first year of life. Treatment takes the two-pronged approach of sebelipase alfa, a human lysosomal acid lipase enzyme replacement therapy (ERT) that improves lipid metabolism, combined with nutritional management. Dietary substrate (lipid) reduction, known as substrate reduction therapy, is essential for optimal management in LAL-D. Following a nutritional plan and managing gastrointestinal disturbances together reduce systemic inflammation and improve growth, gut function, liver health, quality of life, and survival in patients with infantile-onset LAL-D. A multidisciplinary specialized team is necessary to manage the highly complex, multisystemic conditions in these patients. Nutritional management of LAL-D has evolved with increasing experience with the clinical management of ERT-treated infantile-onset LAL-D. A review of guidance for best practice nutritional management is needed. This narrative review aims to provide updated recommendations and guidance for the optimal nutritional management of infantile-onset LAL-D.