Focal and segmental glomerulosclerosis and porteinuria associated with unilateral renal agenesis.

Because reduction of renal mass (nephrectomy) can promote the development of focal glomerulosclerosis in animals, we asked whether patients with unilateral renal agenesis might have similar lesions in the solitary kidney. We describe here the clinical course and pathologic findings of eight patients who developed focal and segmental glomerulosclerosis (FGS) in their solitary kidneys. A review of 586 surgical pathology renal specimens (452 biopsies and 134 nephrectomies) revealed 29 (4.9 per cent) cases of FGS; five also had unilateral renal agenesis (p = 2.1 x 10(-7)). In 9200 autopsies, seven cases of unilateral renal agenesis were found; two (29 per cent) died of chronic renal failure with FGS lesions, and five did not have FGS. The eighth patient was identified because he was the father of a patient in this series. At the time of diagnosis the median age of the patients with unilateral renal agenesis and FGS was 25 years; seven of eight were male. All had proteinuria; four had more than 3 gm. per 25 hours (range, 1.2 to 9.0 gm. per 24 hours). Six developed chronic renal failure, and four died of their renal disease. Two of the patients were related (father and son). One patient had clinical and morphologic evidence of reflux nephropathy. The glomerular lesions were characterized by focal and segmental scarring and adhesions in glomeruli, IgM and C3 deposition by immunofluorescence, and foot process loss and capillary loop collapse by electron microscopy. Our series, although small, indicates that patients with unilateral renal agenesis are significantly more likely to develop FGS than patients with two kidneys. In contrast, FGS did not develop after adult nephrectomy in 10 patients who died 8 to 46 years after adult unilateral nephrectomy. The reason for this association was not established; however, these findings are in accord with experimental studies in which subtotal nephrectomy in young animals promotes FGS. In that setting and in these patients, glomerular damage may result from glomerular overload.