Background: Progression of renal failure is associated with altered lipoprotein metabolism. Apolipoprotein E polymorphism is an important genetic marker for dyslipidemia. The main purpose of this retrospective study was to examine the influence of apolipoprotein E polymorphism and serum lipids level on the progression rate in a group of patients with kidney diseases of diverse etiology.
Methods: Progression rate, with regard to apolipoprotein E polymorphism and initial serum creatinine value, median (162 micromol/l), was determined by reviewing the charts of 385 patients on renal replacement therapy with a median follow-up time of 4.85 years.
Results: Progression rate was negatively correlated to serum cholesterol in the group with type 2 diabetes (p= 0.001). In addition, the urine albumin excretion rate (UAER) was higher in type 2 diabetics carrying the epsilon2 allele (2.1 g/l) as compared to non-epsilon2 allele carriers (1.2 g/l) (p=0.009). Although serum cholesterol in patients with autosomal dominant polycystic kidney disease (ADPKD) carrying the apolipoprotein epsilon4 allele was 5.87 +/- 1.0 mmol/l, which was significantly higher compared to non-epsilon4 carriers, 4.97 +/- 1.1 mmol/l (p=0.026), progression rate was similar in the two groups, 4.4 +/- 0.8 micromol/l/year. An increase in the relative frequency of the apolipoprotein epsilon4 allele was found in patients with ADPKD (0.29), as compared to (0.16) in the rest of the diagnostic groups (p=0.0023). In addition, in the whole study population a positive correlation was found between progression rate and underlying disease (p < 0.005), UAER (p < 0.005) and blood pressure (p < 0.005).
Conclusions: The results of the present study indicate that the decline of renal function in patients with diabetes type 2 may not be associated with levels of plasma cholesterol, but with triglyceride lipoproteins, considered remnant lipoproteins. Any association between cholesterol and apolipoprotein epsilon4 allele with progression in ADPKD may not necessarily be straightforward since this disease is influenced by other genetic and unidentified factors.