The Familial Hyperchylomicronemia Syndrome: New Insights Into Underlying Genetic Defects

SELECTED CASE A 5-YEAR-OLD black boy was referred for evaluation of hypertriglyceridemia and recurrent episodes of abdominal pain. The proband, a 3.9-kg full-term infant with an uncomplicated gestation and vaginal delivery, was noted to have markedly lipemic plasma at 1 week of age. For the first 6 months of life, the infant suffered from severe abdominal bloating associated with emesis, which appeared to be temporally related to feeding. The frequency of these episodes decreased after the diet was changed to a medium-chain triglyceride—enriched formula. However, as the patient grew older, he continued to experience repeated episodes of severe abdominal pain associated with nausea and vomiting, and he was hospitalized twice with documented pancreatitis at the ages of 4 and 5 years. Fasting plasma triglyceride levels during the hospitalizations were 23.7 and 33.9 mmol/L, respectively. Family history was negative for the presence of hyperlipidemia, xanthomas, and pancreatitis. The parents' fasting triglyceride