IgA Nephropathy: History, Classification, and Geographic Distribution

Abstract

Jean Berger, a French pathologist, “discovered” immunoglobulin A (IgA) nephropathy. With Hinglais, he applied fluorescein-conjugated antibodies to IgA to human renal biopsy material for the first time [1, 2]. Approximately 25% of the 300 renal biopsies fluoresced strongly with IgA antisera and, although a few of these biopsies were taken from patients with systemic lupus erythematosus (SLE), Henoch-Schonlein purpura (HSP), and other systemic diseases, the majority were from patients with no overt systemic symptoms. In these latter biopsies, the IgA fluorescence was mesangial in position and accompanied by IgG and C3. IgA was the predominant immunglobulin. The patients suffered recurring bouts of macroscopic hematuria or persistent microscopic hematuria. It is a tribute to Berger’s persistence and determination that IgA nephropathy has emerged in a relatively short space of time as the most common form of glomerulonephritis in the world, as at first Berger’s observations were greeted with some disbelief. The high incidence of this newly discovered disease prompted nephrologists to regard the entity as uniquely French. In addition, the specificity of IgA antisera used was questioned. In the early 1970s, Berger’s disease, an eponym applied to the disease, was frequently couched in tones of skepticism. As immunofluorescence techniques were applied more widely, however, the high incidence of IgA nephropathy described by Berger was confirmed, first in France, then gradually in many other countries.