Cystinuria following Successful Kidney Transplantation in a Small Child: A Rare but Serious Complication

Introduction: Cystinuria, an autosomal recessive hereditary renal-tubular disorder is the most common genetic cause of nephrolithiasis in children and characterized by the impaired reabsorption of the amnio acids cystine, ornithine, lysine and arginine. Mutations in the genes SLC3A1 and SLC7A9, encoding defective cystine transporter subunits have been identified as being responsible for most cases. Case Description: We describe the case of a seven year old girl with autosomal recessive polycysic kidney disease and PKHD1-mutaion who received peritoneal dialysis for 16 months. Kidney transplantation from a deceased donor was successfully performed at the age of 4 years and 10 months. The kidney donor died from brain damage at the age of 14 months (10 kg, 80 cm). Pre-existing medical conditions of the donor were excluded, blood chemistry was normal and both kidneys showed no abnormalities in ultrasound and CT scan. Creatinine normalized within 3 days following renal transplantation (RTx) and the girl showed an uncomplicated clinical course. Nine months after RTx she was admitted with acute post-renal kidney failure with renal pelvic dilatation caused by obstruction with kidney stones in the transplanted kidney. Kidney function normalized quickly after insertion of an ureteral double-J cathether. Cystine stones were diagnosed and two compound heterozygous, pathological mutations in the donor SLC3A1-gene (c.647C>T, o.T216M and c.1400T>C, p.M467T) were deteced later on. The second donor kidney could not be transplanted and did not show concrements. The clinical course of our patient was complicated by 5 ureterorenoscopic stone displacements, repeated insertions of ureteral double-J catheters and three episodes of pyelonephritis. The girl presents now a stable renal function for the past 20 months (GFR 65 ml/min/1.73m2) after repeated surgery, urine alkalization and reduction of the tubular cystine-reabsorption. Discussion: Teaching point: Deceased young donor clinical factors may have a major impact on patient and/or kidney allograft survival. Cystinuria of the donor in this case was not diagnosed in advance because of the young donor age and missing early clinical symptoms. In the context of time-pressured decision-making and despite the good clinical outcomes of RTx with young donors, one has to consider that rare inherited diseases can be transferred accidentally.