This report described 45-year-old identical twin sisters with IgA nephropathy. Case 1 presented with microscopic hematuria and proteinuria at the age of 39. Case 2 was found proteinuria at the age of 32. Both the physical examination and laboratory data of these cases were normal. Serum level of IgA was not elevated. The renal biopsy specimen of two cases showed slight mesangial proliferation by light microscopy and mesangial IgA deposition by immunofluorescence microscopy. Their serotype for HLA was found to be HLA-A2, A24, Bw35, Cwl, Cw3, DRw8, DRwl2. Several reports indicated the familial occurrence of patients with IgA nephropathy and a strong association with HLA-Bw35 in those patients. The present cases also suggested that an abnormal immune responselinked HLA system may be involved in the development of IgA nephropathy.
