Familial defective apolipoprotein B-100

Area of Science:

• Genetics
• Cardiovascular Medicine
• Biochemistry

Background:

• Abnormal interactions between low-density lipoprotein receptors (LDLR) and apolipoproteins (apo B, apo E) lead to elevated plasma lipoprotein levels.
• Mutations in LDLR cause familial hypercholesterolemia (FH), while apo E mutations cause type III hyperlipidemia.
• Specific mutations in the apo B gene result in familial defective apolipoprotein B-100 (FDB), characterized by impaired lipoprotein catabolism.

Purpose of the Study:

• To investigate the incidence and characteristics of familial defective apolipoprotein B-100 (FDB) in Denmark.
• To compare the clinical and biochemical profiles of FDB with familial hypercholesterolemia (FH).
• To evaluate the effectiveness of lipid-lowering therapies in FDB patients.

Main Methods:

• Development and application of DNA-based assays, including DGGE, to detect apo B mutations.
• Analysis of lipid profiles, cholesterol levels, and cardiovascular disease prevalence in FDB patients and their relatives.
• Compilation of data from FDB patients across multiple countries (Netherlands, Germany, Denmark).
• Prospective and retrospective studies on the efficacy of lipid-lowering drugs (pravastatin, gemfibrozil) in FDB.

Main Results:

• The apo B-3,500Arg-Gln mutation was found with an incidence of 1/1250 in Denmark, with no other mutations detected in Danish hypercholesterolemic patients.
• FDB patients exhibited significantly increased total and LDL cholesterol, but with considerable variation and lower LDL elevation compared to FH.
• Age, gender, and LDLR gene variations contributed to the variation in lipid levels among FDB patients.
• FDB patients had a lower age-specific prevalence of atherosclerotic cardiovascular disease (CVD) than FH patients.
• Lipid-lowering therapies showed comparable effectiveness in FDB patients to that observed in FH and type IIa hypercholesterolemia.

Conclusions:

• Familial defective apolipoprotein B-100 (FDB) is a significant genetic cause of hypercholesterolemia with a distinct clinical profile.
• FDB is associated with less severe hypercholesterolemia and a reduced risk of cardiovascular disease compared to familial hypercholesterolemia (FH).
• Standard lipid-lowering treatments are effective for managing hypercholesterolemia in FDB patients.