IgA nephropathy in blacks and Indians of Natal.
IgA nephropathy besides exhibiting a characteristic geographical distribution has been noted to have a low incidence in the blacks of the USA. There is a paucity of data on IgA nephropathy in the blacks of Africa. We report our findings among the blacks and compare these with Indians. An analysis of the primary glomerular diseases of 252 blacks and 75 Indians over 6 years (1981-1986) was done. Mesangiocapillary glomerulonephritis was the commonest type in the black (35.7%), whereas mesangial proliferative glomerulonephritis was the commonest in Indians (26.7%). IgA nephropathy occurred in 2 blacks (1 male, 1 female), whereas there were 10 Indians (8 males, 2 females). Available data among whites in Natal show that IgA nephropathy is not uncommon. HLA studies done in blacks with IgA nephropathy did not reveal the HLAB35 or the DR4 antigen. HLAB35 in our blacks is less common compared to Indians and whites of Durban. Thus, although glomerulonephritis is common in blacks, IgA nephropathy is rare. This suggests that infection which is common in our black population may not be responsible for the aetiology of IgA nephropathy. A dietary factor in the form of a high-fibre diet may protect the black population from IgA nephropathy. However, a genetic factor cannot be excluded.