As expected and consistent with current knowledge, the diversity and the abundance of commensals (3, 32, 40), measures of the CF defect in sweat duct and respiratory epithelium (62), as well as spirometry as an indicator of lung function (44, 47) correlated within their functional categories of metagenome, CFTR activity, and lung function, respectively. Here, CFTR is linked to cystic fibrosis.