Recent evidence correlating P. jirovecii as a comorbidity agent in respiratory conditions like chronic obstructive pulmonary disease (COPD) (5) or pneumonia in association with anti-tumor necrosis factor (TNF) antibody therapies (6) or with lung cancers (7) indicates a broadening of the population susceptible to PCP. The gene discussed is TNF; the disease is chronic obstructive pulmonary disease.