C3 glomerulonephritis and thrombotic microangiopathy of renal allograft after pulmonary infection in a male with concomitant two complement factor I gene variations: a case report

It has been suggested that C3 glomerulonephritis (C3GN) and atypical hemolytic-uremic syndrome (a stereotypical phenotype of thrombotic microangiopathy), two rare entities caused by complement alternative pathway dysregulation share overlapping genetic origin and can be triggered by infections. We report a case of concomitant C3GN and thrombotic microangiopathy (TMA) after pulmonary infection in a young male receiving kidney transplantation. Genetic assessment revealed two missense variations in compound heterozygous form in CFI gene (complement factor I). These two variations are segregated with disease in the core family member of this patient. Plasma CFI levels of the patient and family members were all in normal range. We considered that these two variations only impair CFI function rather than its quantity in the serum. Our case supports that C3GN and TMA shared overlapping genetic variations and might be triggered by infection in genetically susceptible patients after kidney transplantation.