Discordant clinicopathological features in monozygotic twins with IgA nephropathy.

This report describes a pair of identical twins with IgA nephropathy (IgAN). One of them showed diffuse mesangial proliferation with crescent formations in the glomeruli, moderate proteinuria and required intensive therapies including corticosteroids for remission. In contrast, the other had only focal mesangial alterations and exhibited only a subtle level of urinary abnormalities throughout the follow-up without steroid therapy. Although our monozygotic twins have completely identical genotypes, the clinicopathological features of their IgAN were quite discordant. The present cases suggest that not only genetic factors but also epigenetic differences may be involved in the progression of IgAN.