LPL and familial chylomicronemia syndrome: Chylomicrons are the largest circulating lipoproteins (> 100 nm), and plasma TG concentration remains elevated (> 10 mmol/L (890 mg/dl)), in patients with the familial chylomicronemia syndrome (FCS) (ORPHA:309,015), a rare autosomal recessive disorder characterized by sustained chylomicronemia due to bi-allelic combinations of loss-of-function (LoF) variants in the LPL gene or in genes coding for proteins essential to LPL efficacy and bioavailability, such as APOC2, GPIHBP1, APOA5 or LMF1 (1).