Prospective analysis of cystic fibrosis transmembrane regulator mutations in adults with bronchiectasis or pulmonary nontuberculous mycobacterial infection.
BACKGROUND
Bronchiectasis and pulmonary infection with nontuberculous mycobacteria (NTM) may be associated with disease-causing mutations in the cystic fibrosis transmembrane regulator (CFTR).


METHODS
Fifty adult patients at Stanford University Medical Center with a diagnosis of bronchiectasis and/or pulmonary NTM infection were prospectively characterized by sweat chloride measurement, comprehensive mutational analysis of CFTR, and sputum culture results.


RESULTS
A de novo diagnosis of cystic fibrosis (CF) was established in 10 patients (20%). Patients with CF were more likely than those without CF to have mucus plugging seen on chest high-resolution CT, and women with a CF diagnosis were thinner, with a significantly lower mean body mass index than the non-CF subjects. Thirty CFTR mutations were identified in 24 patients (50% prevalence). Sweat chloride concentration was elevated > 60 mEq/dL (diagnostic of CF) in seven patients (14%), and from 40 to 60 mEq/dL in eight patients (16%). The frequency of CFTR mutations was elevated above that expected in the general population: heterozygous DeltaF508 (12% vs 3%), R75Q (14% vs 1%), and intron 8 5T (17% vs 5 to 10%). Other known CFTR mutations identified were V456A, G542X, R668C, I1027T, D1152, R1162L, W1282X, and L183I. Three novel CFTR mutations were identified: A394V, F650L, and C1344S.


CONCLUSIONS
Mutations in CFTR that alter RNA splicing and/or functional chloride conductance are common in this population, and are likely to contribute to the susceptibility and pathogenesis of adult bronchiectasis and pulmonary NTM infection. Careful clinical evaluation for disease cause should be undertaken in this clinical context.
Ziedalski
Tomasz M
TM
Division of Pulmonary and Critical Care Medicine, Stanford University Medical Center, 300 Pasteur Dr, Stanford, CA 94305-5236, USA.
Kao
Peter N
PN
Henig
Noreen R
NR
Jacobs
Susan S
SS
Ruoss
Stephen J
SJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D001987:Bronchiectasis / Q000175:diagnosis / Q000235:genetics*; D018118:Chloride Channels / Q000235:genetics; D002712:Chlorides / Q000032:analysis; D003550:Cystic Fibrosis / Q000175:diagnosis / Q000235:genetics*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D004252:DNA Mutational Analysis; D005091:Exons; D005260:Female; D006580:Genetic Carrier Screening; D005838:Genotype; D006801:Humans; D007438:Introns; D008171:Lung Diseases / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D015270:Mycobacterium avium-intracellulare Infection / Q000175:diagnosis / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012326:RNA Splicing / Q000235:genetics; D013542:Sweat / Q000737:chemistry; D036542:Tomography, Spiral Computed
C505032:CFTR protein, human; D018118:Chloride Channels; D002712:Chlorides; D019005:Cystic Fibrosis Transmembrane Conductance Regulator