Apolipoprotein E polymorphism and renal function in German type 1 and type 2 diabetic patients

Area of Science:

• Nephrology
• Endocrinology
• Genetics

Background:

• Diabetic nephropathy is a major complication of diabetes mellitus.
• Apolipoprotein E (Apo E) polymorphism is associated with lipid metabolism and cardiovascular disease.
• The role of Apo E polymorphism in diabetic kidney disease requires further investigation.

Purpose of the Study:

• To investigate the association between Apo E genotypes and renal function in patients with type 1 (IDDM) and type 2 (NIDDM) diabetes.
• To determine if Apo E polymorphism is an independent risk factor for renal dysfunction in diabetic patients.

Main Methods:

• Apolipoprotein E genotyping, lipid profiles, creatinine clearance (CCr), and urinary marker protein excretion were assessed in 162 IDDM and 124 NIDDM patients.
• Marker proteins (albumin, IgG, alpha 1-microglobulin) were used to evaluate glomerular filtration and tubular reabsorption.
• Statistical analyses included ANOVA and multiple linear regression.

Main Results:

• NIDDM patients exhibited higher lipid levels and lower CCr compared to IDDM patients.
• In IDDM patients, Apo E genotypes were associated with CCr, with a decreasing glomerular filtration rate observed in the order: epsilon 4/epsilon 4 > epsilon 4/epsilon 3 > epsilon 3/epsilon 3 > epsilon 2/epsilon 2 > epsilon 2/epsilon 3.
• The epsilon 2 allele in IDDM patients independently predicted lower CCr and increased urinary excretion of albumin, IgG, and alpha 1-microglobulin.

Conclusions:

• Apo E polymorphism influences serum lipoprotein levels in both IDDM and NIDDM patients.
• Apo E polymorphism represents a clinically relevant renal risk factor, particularly in normolipidemic IDDM patients.