A. All estimated glomerular filtration rate (eGFR) measurements for each group are included (signal group green, prosegment group red, mature group black). A best-fit line is included for each group. Patients in the mature group presented later in life and had normal kidney function at earliest measurement. Patients in the signal and prosegment group often presented early in life, and eGFR was significantly decreased from the time of first measurement in most patients. B. eGFR values in 13 children with longitudinal follow-up from the signal group. Each child is represented by a different color with a best-fit line, and the REN mutation is given in the legend. Despite having low eGFR values at earliest measurement, kidney function remained stable until age 20 in most patients.