Siblings with IgA nephropathy and diffuse proliferative glomerulonephritis (PGN) associated with identical HL-A antigens.

Siblings with IgA nephropathy and diffuse proliferative glomerulonephritis without mesangial IgA deposits (PGN) who had identical HL-A antigens are described. A 21-year-old woman suffered from IgA nephropathy and her 27-year-old sister showed diffuse proliferative glomerulonephritis (PGN) distinct from IgA nephropathy. These siblings had identical HL-A alloantigens which were A2, Aw24; Bw16, Bw35; Cw4, Cw7; DR4. Microhematuria and increased serum IgA levels were shown in their father and other sister but renal biopsies were not performed. The serotypes for the HL-A antigens of their father and other sister were A2, Aw24; Bw27, Bw35; Cw4; DR4 and A2; Bw16; Cw7; Dr2, respectively. It is demonstrated that IgA nephropathy and PGN share a common HL-A phenotype including DR4. It is postulated that the presence of DR4 antigens is not directly related to the occurrence of IgA nephropathy.