The mean BMI in COPD patients was significantly lower than in controls (BMI = 18.1 +/− 2.7 kg/m2 versus 22.8 +/− 2.2 kg/m2 respectively; p< 0.0001), which may explain the lower leptin levels seen in COPD patients (p < 0.05). The gene discussed is LEP; the disease is chronic obstructive pulmonary disease.