Outcomes of kidney transplantation in patients with lysinuric protein intolerance.

Background: Lysinuric protein intolerance (LPI) is a metabolic disorder that leads to dysfunctional intestinal absorption and kidney clearance of cationic amino acids. Chronic kidney disease develops in many LPI patients and leads to end-stage kidney disease in at least 10% of patients. Since data on kidney transplants in LPI patients are limited, we analysed the outcomes of LPI patients after transplantation in Finland. Methods: This retrospective cohort study includes all Finnish LPI patients who have received a kidney transplant. The data were collected from the Finnish Transplant Registry and electronic medical records from 2005 through May 2023 or patient death. The plasma amino acid profile was analysed before and after transplantation. Results: Eight LPI patients (75% female, mean age at transplant 41.9 years) received a kidney allograft and two of the patients received a second transplant. Nine transplants were from deceased donors and one was from a living donor. Acute rejection occurred after four transplantations (two T-cell mediated and two antibody mediated). One patient died 6 months after transplantation due to alveolar proteinosis. Apart from lower citrulline and higher lysine concentrations, plasma amino acid levels showed no changes after transplantation. The 1-, 5- and 10-year graft survivals were 80%, 68.6% and 51.4%, and patient survivals were 88%, 86% and 50%, respectively. Conclusions: Kidney transplantation is feasible in patients with LPI, although the acute rejection rate seems high and severe complications such as pulmonary alveolar proteinosis may occur. Transplantation led to changes in plasma citrulline and lysine concentrations.