Use of a B-cell depleting regimen for antifactor H autoantibody-mediated membranoproliferative glomerulonephritis in a paediatric patient.

A male child presented initially well with a mixed nephrotic-nephritic syndrome and was commenced on standard high-dose oral corticosteroids. Clinical deterioration occurred 3 weeks later with rapidly progressing renal dysfunction, seizures and diminished urinary output, requiring renal replacement therapy. Once stabilised, renal biopsy demonstrated mesangial and capillary C3, minimal IgG deposition, with mesangial electron dense deposits felt consistent with postinfectious glomerulonephritis or C3 glomerulopathy. Further investigations identified circulating autoantibody directed against factor H, as a plausible aetiology of the membranoproliferative glomerulonephritis (MPGN). Treatment with rituximab and mycophenolate mofetil was associated with a reduction in antibody titres and a concurrent reduction in proteinuria and normalisation of renal function.Subsequent monitoring of antibody titres prompted further administrations of rituximab, with reduction in titres demonstrated after repeat doses. Atypical presentations or complications of nephrotic syndrome or MPGN should prompt detailed investigations for the cause with consideration of antifactor H antibodies.