The clinical features of acute BRHP include the reproduction of symptoms following exposure to an avian antigen, the presence of specific IgG or IgA antibodies to PDE in the sera and BAL fluid, the proliferation of either BAL or peripheral lymphocytes in response to pigeon sera, the finding of lymphocytosis in the BAL fluid, and the presence of both alveolitis and granulomatous lesions in the lungs [6,7]. The gene discussed is ALDH7A1; the disease is hypersensitivity pneumonitis.