PSMA6 and cystic fibrosis: Tuberculosis, CF, PCD, gastroesophageal reflux disease, alpha-1 anti-trypsin deficiency and atopy were ruled out on the basis of normal or negative results of purified protein derivative test, sweat test, cilia motility and ultrastructure assessment at nasal brushing, prolonged pH-metry, serum alpha-1 anti-trypsin level, and skin prick test and serum IgE levels to the most common food and inhalant allergens.