THE INFLUENCE OF FAMILIAL FACTORS ON THE PROGRESSION OF IGA NEPHROPATHY

Background. Vascular risk factors in first degree relatives of patient s with insulin dependant diabetes mellitus are known to increase the r isk of that patient developing diabetic nephropathy. We explored the i nfluence of vascular risk factors in first degree relatives on patient s with stable (serum creatinine <150 mu mol/l for >5 years) and progre ssive (serum creatinine >200 mu mol/l, and >150% serum creatinine at p resentation, after minimum follow-up at 2 years) IgA nephropathy (IgAN ). Methods. We compared solidum-lithium countertransport activity (SLC V-max plasma lipoprotein(a) and von Willebrand factor(vWf) concentrat ions, incidence of vascular disease, and incidence of hypertension in 37 first degree relatives of 23 patients with stable IgAN and 33 first degree relatives of 17 patients with progressive IgAN. The two groups of relatives were comparable with respect to other risk factors: age, smoking, blood pressure, and plasma glucose, creatinine, cholesterol and triglyceride concentrations. Results. SLC V-max was higher in rela tives of stable patients (mean 0.37 mmol/h/l RBC [S.D. 0.18] vs 0.30 [ S.D. 0.09]; P=0.034 two-sample t-test). There was no difference betwee n the relatives of stable and progressive patients in plasma lipoprote in(a) concentration (median 11.5 mg/l vs 13.0: P=0.45; 95% C.I. -12 to 3; Mann-Whitney test), plasma vWf concentration (149.4 IU/dl [S.D. 55 .6] vs. 163.2 IU/dl [S.D. 57.3]; P=0.31 two-sample t-test), or inciden ce of hypertension (13/37 [35.1%] vs 10/33 [30.3%];; chi(2)=0.185; P=0 .667). Relatives of patients with progressive IgAN had a slightly high er incidence of vascular disease (10/33 [30.3%] vs 8/37 [21.6%]; chi(2 )=0.688; P=0.407). Conclusions. Familial Vascular risk may increase th e likelihood of progressive renal failure in patients with IgAN but th e influence is likely to be small and unrelated to the factors we meas ured. SLC Vmax was significantly higher in relatives of patients with stable disease which contrasts with data from other studies and is une xplained.