GPIHBP1 and familial lipoprotein lipase deficiency: Overall, drastically reduced LPL activity (<10 μmol/l/min) was discovered in 11 TVHTG patients (TG mean ±SD: 20.5±27.0 mmol/l): 5 of which were identified with obvious causal genotypes in either LPL or GPIHBP1 genes and 4 of which had genotypes most likely to contribute to their hyperchylomicronemia.