Mutations in LPL gene, but when in autosomal recessive biallelic pathogenic variant or compound heterozygous variant, cause more than 80% of cases of familial chylomicronemia syndrome that is an extremely rare variant of hypertriglyceridaemia (prevalence is in the range of 1:100 000 to 1:1 000 000) with a very prominent effect. The gene discussed is LPL; the disease is hypertriglyceridemia.