In addition, other serum markers such as antiglomerular basement membrane antibody (20% change overlapping with positive ANCA [26]) and angiotensin converting enzyme for sarcoidosis [27] should be tested before any invasive lung biopsies to rule out infection, interstitial lung disease with unknown etiology, and vasculitis/granulomatosis/sarcoidosis. The gene discussed is ACE; the disease is infection.