Accordingly, this study sought to: (1) compare airway (and plasma) FABP4 levels in COPD and healthy volunteers and, (2) study their relationship with presence of airway infection, quantity and proportion of Mɸ and several clinical markers of disease severity, such as the severity of airflow limitation (FEV1), the GOLD classification and the level of symptoms (CAT questionnaire). This evidence concerns the gene FABP4 and chronic obstructive pulmonary disease.