Apolipoprotein E genetic polymorphism influence the susceptibility to nephropathy in type 2 diabetes patients.

BACKGROUND: An association between Apolipoprotein E (Apo E) alleles and genotypes and diabetic nephropathy (DN) was suggested, but with inconsistent results. We tested the relationship between serum lipids, Apo E alleles and genotypes with type 2 diabetes (T2DM), and DN pathogenesis.

METHODS: Study subjects comprised 1389 normoglycemic controls, and 1422 T2DM patients, of whom 825 were normoalbuminuric (DWN), and 597 presented with nephropathy (DN).

RESULTS: Significantly lower Apo ε2, and higher Apo ε4 allele frequencies was seen among T2DM patients than controls. Significantly higher frequency of ε3/ε4, and lower frequencies of ε3/ε3, ε2/ε3, and ε4/ε4 carriers was seen among T2DM cases. Apo ε2-carrying individuals were more frequently found in controls than in patients, while significantly higher frequency of ε4-carrying genotypes was seen in T2DM cases. Significantly higher ε2, and lower ε3 allele frequencies were noted for DN group compared to DWN group. Significantly higher frequency of ε2-containing ε2/ε3 and ε2/ε4, and lower frequencies of ε3/ε3 carriers was seen among DN cases. Apo ε3/ε3 was associated with higher total cholesterol, LDL-cholesterol, and triglyceride levels in DN patients, and significantly higher triglyceride levels were seen in ε2/ε3-carrying DN patients. Logistic regression analysis confirmed the association of Apo ε3-containing ε3/ε3, ε2/ε3, and ε3/ε4, and Apo ε2-containing ε2/ε4 with DN, after controlling for key covariates.

CONCLUSION: The results of this case-control study provide evidence that the ε2 and ε3 alleles of APOE modify lipid profile, and constitute independent risk factors of DN in type 2 diabetes. The molecular mechanisms underlying this risk is discussed.