Chronic glomerulonephritis associated with IgG subclass deficiency

We experienced two patients with IgG subclass deficiency who suffered from chronic glomerulonephritis (GN). Patient 1 was a 17-year-old girl with IgG subclass deficiency (combined deficiency of IgG2 and IgG4). Renal biopsy was performed when she was aged 16 years, and she was diagnosed with membranoproliferative GN. Patient 2 was a 16-year-old girl with IgG subclass deficiency (combined deficiency of IgG2, IgG3, and IgG4). Renal biopsy was performed when she was aged 15 years, and she was diagnosed with membranous nephropathy. We examined the glomerular deposition patterns of their IgG subclasses. Furthermore, we compared their clinical and laboratory findings with those of three patients with IgG subclass deficiency without GN. Patients with GN suffered infections more frequently than those without GN. The serum levels of IgG (especially IgG1) and IgM were higher in patients with GN than in those without GN. In patient 1 IgG1 and IgG3 were deposited in a mesangiocapillary pattern, but, in patient 2, only IgG1 was deposited in a capillary pattern. Thus, the different patterns of IgG subclass deficiency between the two patients may be responsible for their different glomerular pathologies. To the best of our knowledge, this is the first report of chronic GN in patients with IgG subclass deficiency.