Nasr et al. (2016) report 20 cases of "atypical anti-GBM disease," characterized by bright, linear glomerular basement membrane (GBM) immunoglobulin deposition in patients who lacked anti-GBM antibodies by conventional testing and who had a relatively benign course. Half had light chain restriction. The term "idiopathic linear immunoglobulin deposition" may be preferable until anti-GBM activity is demonstrable, since there are alternative mechanisms of linear deposition in the GBM, including physicochemical affinity for GBM components and alterations of the GBM itself.
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