Association of complement receptor 1 (CR1, CD35, C3b/C4b receptor) density polymorphism with glomerulonephritis in Indian subjects.

Complement receptor 1 (CR1, CD35, C3b/C4b receptor), a polymorphic membrane bound glycoprotein is important both as a complement regulatory protein, and as a vehicle for immune complex clearance. It is differentially expressed on erythrocytes, eosinophils, monocytes, B and T-lymphocytes, dendritic cells and kidney podocytes. It also occurs in the plasma as soluble CR1 (sCR1) and in urine as urinary CR1 (uCR1). Different population studies have either suggested or refuted the functional and physiological significance of genomic (HH, high erythrocyte CR1 expression; HL, intermediate and LL, low expression) polymorphism of CR1 in health and disease. Prevalence of autoimmune disorders like RA, GN and SLE is higher in Asian-Indians compared to the western world. Although several studies from India emphasize the modulation of E-CR1 levels as a key factor in the pathophysiology of glomerulonephritis (GN), none of them, however, provide much information on the role of CR1 gene variance in this context. We, therefore, carried out the study of CR1 polymorphism in 117 normal Indian subjects and 65 patients suffering from glomerulonephritis in order to study its possible association with the disease and E-CR1 levels. This is the first study of its kind in the Indian population, in which, the direct effect of a particular genotype on the E-CR1 levels and its possible association with the disease has been studied simultaneously.