The pioneering observations by Tashkin and colleagues [26], and others, although conducted in the 1990s, reported important and relevant findings showing that heavy cannabis smoking weakens the immune system, resulting in a wide range of respiratory/pulmonary complications including chronic bronchitis, coughing, production of sputum, wheezing, impaired pulmonary function, pulmonary responsiveness, abnormalities in the large airways, and decline in respiratory function [27], possibly through a reduction in T-cell proliferation and IFN-gamma production, via the CB2 receptor pathway [26]. The gene discussed is IFNG; the disease is chronic bronchitis.