Pathology of IgA nephropathy: A global perspective

Worldwide adoption of the Oxford Classification of IgA nephropathy (IgAN) has enabled comparison of pathology data from clinicopathological studies in different regions of the world. It is apparent that the frequency of Oxford Classification MEST‐C scores shows geographic variations. These in part reflect differences in the stage of disease at diagnosis, criteria for performing biopsies and inclusion in clinical studies, and pathologist reporting practice. However, there appears to be a true geographic difference in the frequency of glomerular inflammation and crescents with a 2–3 fold greater proportion of patients showing these changes in East Asia when compared to Europe and North America. This indicates that the pathology of IgAN is influenced by genetic background. Geographic differences in the pathology of IgAN might underly the reported differences in clinical presentation and outcome in different regions of the world, and has important implications for clinical trials and patient management. Summary at a glance The frequency of Oxford Classification MEST‐C scores shows geographic variations that might in part reflect differences in clinical practice. However, the relatively high frequency of glomerular crescents in patients from East Asia when compared to the West indicates that glomerular inflammation in IgA nephropathy is influenced by genetic background.