A 25-year-old man with a history of abdominal pain presents with a serum showing increased chylomicrons. What is the most likely disorder?

The presence of increased chylomicrons in the serum points to a disorder that affects lipid metabolism, specifically the processing of triglycerides and chylomicrons. Chylomicrons are lipoprotein particles primarily responsible for transporting dietary lipids from the intestines to other locations in the body. An elevation in chylomicrons often indicates a defect in their metabolism, which is characteristic of familial hyperchylomicronemia.

Familial hyperchylomicronemia, also known as type I hyperlipoproteinemia, is typically due to a genetic defect involving the lipoprotein lipase enzyme or its cofactor, apolipoprotein C-II. This disorder leads to impaired clearance of chylomicrons from the bloodstream, resulting in their accumulation and subsequent elevation in the serum. Patients with this condition frequently experience symptoms such as abdominal pain (often due to pancreatitis), and they may have features such as eruptive xanthomas or milky plasma.

This specific disorder is distinct from others mentioned, which do not primarily involve elevated chylomicrons. For instance, familial hypercholesterolemia is characterized by high levels of low-density lipoprotein (LDL) rather than chylomicrons, and combined hyperlip