IGA nephropathy in HLA-identical siblings.

This report describes a patient with end stage IgA nephropathy who received a renal transplant from his asymptomatic HLA-identical brother. A biopsy of the donor kidney performed at the time of transplantation showed evidence of widespread electron-dense mesangial deposits. On immunofluorescence these deposits stained with IgA, documenting clinically occult IgA nephropathy in this otherwise healthy donor. These findings are of particular interest in view of the association of IgA nephropathy with the HLA-Bw35 alloantigen, and raise the possibility that asymptomatic disease, already present in a donor kidney, may have accounted for what has previously been called "recurrence" of this disease in renal allograft recipients.