Background: For young infants with congenital nephrotic syndrome of the Finnish type (CNF), the timing of kidney transplantation has always been controversial, as the limitation of their abdominal space for graft placement and increased mortality during dialysis both contributed to the dilemma. The aim of our study was to analyze the outcomes of early pre-emptive renal transplantation in infants with congenital nephrotic syndrome of the Finnish type, who were aged<1 year at KTx, focusing on surgical complications, as well as graft survival and patient survival.
Methods: we retrospectively searched for infants with Congenital Nephrotic Syndrome who underwent KTx at an age <1y, during June 2017 and August 2024 in our center. They were divided into two groups based on the gene mutation, CNF group and non-CNF group.
Results: A total of 21 cases of kidney transplants were performed in 19 young infants (<2y) with congenital nephrotic syndrome during the study period. 10 out of 21 cases were diagnosed CNF and aged<1y at KTx except 1 case. Infants with CNF were at younger age and had lower body weight at the time of KTx, compared with those diagnosed non-CNF. (Mean weight 5.7±1.8kg vs 8.6±1.8kg, p=0.002; Mean age 0.5±0.2y vs 1.2±0.1y, p<0.001). Pre-emptive transplants were performed in 60% of CNF infants, while only 27.3% in non-CNF infants. Over 70% of recipients had native kidney nephrectomy during transplantation and graft implanted intraperitoneally in both groups. Implementation of induction therapy and steroid withdrawal showed no significant difference between two groups. Median donor age in CNF infants was 4.5(0.3-26) months, younger than 5(0.6-60) months in non-CNF infants(p=0.35). Median weight of donors were 6.5(3.5-10) kg and 7(2.8-20) kg in CNF and non-CNF infants, respectively (p=0.48). The overall incidences of surgical complications and acute rejection as well as infection were not significantly different between the groups. Median estimated glomerular filtration rate was significantly higher in CNF infants before transplantation (68.9ml/min/1.73m2 vs 5.9 ml/min/1.73m2, p=0.014). The lead was maintained until 3 years post-transplant despite the significance disappeared. Catch-up growth was obvious in both groups but no significant difference was observed at each time point. Graft survival rates at 1 year post-transplant for CNF infants and non-CNF infants were 80% and 100% respectively, without statistical difference. Two grafts were lost in CNF infants, one from renal artery thrombosis, one from acute rejection. Both proportions remained still until 3 years post-transplant. Patient survival rates were 100% for both groups during the first year post-transplant, while the CNF group declined to 83.3% at 3 years post-transplant, as 1 recipient died from EBV-associated PTLD. No significant differences in patient survival were observed between two groups.
Conclusions: Despite the lower weight and younger age of CNF infants at KTx compared to non-CNF infants, satisfying clinical outcomes were achieved after pre-emptive transplantation with simultaneous bilateral nephrectomy.