Low birth weight and nephron mass and their role in the progression of chronic kidney disease: a case report on identical twins with Alport disease.

We report the outcomes of 47-year-old monozygotic twins with Alport syndrome, who share the same maternal and genetic factors; however, in adulthood have discordant trajectories in the decline of their renal function. The twin with the more rapid progression to renal failure was born with low birth weight (LBW), suggesting congenital nephron deficiency and increased susceptibility to progressive renal disease, despite having the same genetically inherited kidney condition. This 'natural experiment' adds further credence to the hypothesis that LBW contributes to the susceptibility to chronic kidney disease. We suggest further studies and surveillance for this high-risk group of infants in order to gain additional insights into the impact of perinatal factors such as LBW.