Severe hyperchylomicronemia in two infants with novel APOC2 gene mutation

Background: Familial apo C-II deficiency is a rare hereditary disorder frequently caused by lipoprotein lipase (LPL) and APOC2 gene mutations. To date, less than 30 patients with familial apo C-II deficiency with 24 different mutations have been identified in the literature. Here, we describe two familial chylomicronemia syndrome cases in infants with two novel mutations of the APOC2 gene. Case presentation: Case 1, a 46-day-old female, was admitted to our hospital for evaluation due to the lipemic appearance of the blood sample. A clinical examination revealed hepatomegaly and lipemia retinalis. Triglyceride level of 6295 mg/dL was decreased with a strict low-fat diet, medium-chain triglycerides (MCT) oil-rich formula and omega-3 fatty acid supplementation. Due to low adherence to the diet, TG elevation was detected and fresh frozen plasma (10 mL/kg/day) was administered for 2 days. A novel homozygous p.Q25X (c.73C>T) mutation in the APOC2 gene was detected. Case 2, a 10-month-old female patient, referred to our center for the differential diagnosis of hyperlipidemia as her blood sample could not be assessed due to its lipemic appearance. Laboratory examinations showed a TG level of 4520 mg/dL which was reduced with a low-fat diet, MCT oil-rich formula and omega-3 fatty acid supplementation. Hepatosteatosis and splenomegaly were determined using abdominal sonography. A novel homozygous IVS2+6T>G (c.55+6T>G) mutation in the APOC2 gene was identified. Conclusions: We describe two novel homozygous mutations (p.Q25X [c.73C>T] and IVS2+6T>G [c.55+6 'G]) in the APOC2 gene in infants with hyperchylomicronemia. To the best of our knowledge, Case 1 is the youngest patient with familial apo C-II deficiency in the literature to date.