The most common causes of CC in patients with normal chest roentgenogram findings who are non-smokers and are not receiving therapy with angiotensin-converting enzyme (ACE) inhibitors are asthma, gastroesophageal reflux disease (GERD), upper airway cough syndrome (UACS)/rhinosinus conditions, and non-asthmatic eosinophilic bronchitis (NAEB) [1,8]. This evidence concerns the gene ACE and asthma.