Familial Lipoprotein Lipase Deficiency

Excerpt

Clinical characteristics: Familial lipoprotein lipase (LPL) deficiency usually presents in childhood and is characterized by very severe hypertriglyceridemia with episodes of abdominal pain, recurrent acute pancreatitis, eruptive cutaneous xanthomata, and hepatosplenomegaly. Clearance of chylomicrons from the plasma is impaired, causing triglycerides to accumulate in plasma and the plasma to have a milky (lactescent or lipemic) appearance. Symptoms usually resolve with restriction of total dietary fat to ≤20 g/day.

Diagnosis/testing: The diagnosis of LPL deficiency is established in a proband by the identification of biallelic pathogenic variants in LPL on molecular genetic testing.

Management: Treatment of manifestations: Treatment is based on medical nutrition therapy to maintain plasma triglyceride concentration below 1000 mg/dL. Maintenance of triglyceride levels below 2000 mg/dL prevents recurrent abdominal pain. Restriction of dietary fat to ≤20 g/day or 15% of a total energy intake is usually sufficient to reduce plasma triglyceride concentration and to keep the individual with familial LPL deficiency free of symptoms. An acute pancreatitis episode is treated with standard care.

Prevention of secondary complications: Prevention of recurrent acute pancreatitis decreases the risk of developing diabetes mellitus.

Surveillance: Monitoring of plasma triglycerides.

Agents/circumstances to avoid: Agents known to increase endogenous triglyceride concentration such as alcohol, oral estrogens, diuretics, isotretinoin, glucocorticoids, selective serotonin reuptake inhibitors, and beta-adrenergic blocking agents; fish oil supplements are contraindicated because they contribute to chylomicron levels.

Pregnancy management: For pregnant women with LPL deficiency, extreme dietary fat restriction to <2 g/day during the second and third trimesters of pregnancy with close monitoring of plasma triglyceride concentration is recommended.

Other: The lipid-lowering drugs that are used to treat other disorders of lipid metabolism are not effective in individuals with familial LPL deficiency.

Genetic counseling: Familial LPL deficiency is inherited in an autosomal recessive manner. Each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Carrier testing for at-risk relatives and prenatal testing for pregnancies at increased risk are possible if the pathogenic variants in the family are known.