Variants of alpha-1-proteinase inhibitor in black and white South African patients with focal glomerulosclerosis and minimal change nephrotic syndrome

Abstract

The objective of this study was to determine the prevalence and biochemical characteristics of certain alleles of alpha-1-proteinase inhibitor in black,coloured and white South African patients with two common types of pathology causing the nephrotic syndrome.

This was a cross sectional study of black, coloured and white patients with focal glomerulosclerosis (FGS) or minimal change disease (MCNS) and black, coloured and white control individuals.

There was a significant increase in the prevalence of the V allele in black patients with FGS (12%) as compared to black controls (1%) (p=0.01). There was also a significant decrease in the Ml (Val'£lj) allele of alpha-1- protease inhibitor in black and coloured patients with FGS (34%) as compared to black and coloured patients with MCNS (62%) (p=0.04). An increase in the prevalence of the S allele of alpha-1-proteinase inhibitor was found in white patients with FGS and MCNS (10%) as compared to white controls (2%)

The plasma elastase inhibitory capacity (EIC) associated with the phenotypes (PI) Ml (Ala213) S, Ml (Ala213) V and Ml (Ala213) Ml (Ala213) was significantly decreased as compared to the EIC associated with PI Ml (Val213) Ml(Val"13). (p=0.006; p=0.004 and p=0.025 respectively).Twelve of the thirteen patients with FGS and infected with tuberculosis had either the Ml (Ala213) , V or F alleles and required transplantation due to the severity of the disease. All of these patients were either black or coloured..

It is possible that the combination of functionally less efficient alpha-1-proteinase inhibitor and an inflammatory challenge associated with an infection such as tuberculosis could predispose black and coloured nephrotic patients to more aggressive scarring in FGS.