Abstract
This inexpensive and noninvasive tool depicted decline in pulmonary health that may be more sensitive than conventional pulmonary function test measures, and study results confirmed that for mutations encountered in the current patient cohort, the severity classification of cystic fibrosis mutations typically applied to pancreatic phenotype may also apply to the pulmonary phenotype.
Purpose
To evaluate the hierarchical phenotypic expression of cystic fibrosis transmembrane conductance regulator (CFTR) genotypes in the respiratory system as has been documented in the pancreas.
Materials and Methods
This study was institutional review board approved; informed consent was not required. HIPAA guidelines were followed. Genotype effects were assessed by using chest radiographic and pulmonary function test (PFT) results in 93 patients. Serial chest radiographic and PFT (percentage of predicted forced expiratory volume in 1 second [FEV1], percentage of predicted forced vital capacity [FVC]) results were compared by using analysis of variance with repeated measures. By using CFTR class of mutations, two groups were created: group S (severe disease) and group M (mild disease). Within group S, three subgroups were created: A consisted of patients with two class I alleles; B, class I allele and class II or III allele; C, class II allele and class II or III allele. Group M consisted of patients with at least one allele from class IV–VI.
Results
Within group S, subgroup A had a faster deterioration than B or C according to radiographic data (A vs B, P = .014; A vs C, P = .009), with only a borderline difference in FEV1 for subgroups A versus C (P = .031). Otherwise, PFTs were not sensitive for distinguishing subgroups. Only radiographic results identified that subgroup B had faster progression than C (P = .003); all parameters had trends of decline in the same direction. Group S had a faster decline than group M (radiography, P = .005; FVC, P = .011; FEV1, P = .529).
Conclusion
Disease progressed more rapidly with gene class hierarchical correlations seen in pancreatic disease. Radiography was more sensitive for identifying differences.
© RSNA, 2009
References
- 1
Cystic Fibrosis Genetic Analysis Consortium . Cystic fibrosis mutation data base. http://www.genet.sickkids.on.ca/cftr/. Published 1989. Updated March 2, 2007.Accessed March 9, 2009 . Google Scholar - 2 . The spectrum of cystic fibrosis mutation. Trends Genet 1992;8:392–398. Crossref, Medline, Google Scholar
- 3 . Molecular mechanisms of CFTR chloride channel dysfunction in cystic fibrosis. Cell 1993;73:1251–1254. Crossref, Medline, Google Scholar
- 4 . Cystic fibrosis: genotypic and phenotypic variations. Annu Rev Genet 1995;29:777–807. Crossref, Medline, Google Scholar
- 5 . Genotype and phenotype in cystic fibrosis. Respiration 2000;67:117–133. Crossref, Medline, Google Scholar
- 6 . Improved respiratory prognosis in patients with cystic fibrosis with normal fat absorption. J Pediatr 1982;100:857–862. Crossref, Medline, Google Scholar
- 7 . Association between genetically determined pancreatic status and lung disease in adult cystic fibrosis patients. Chest 2002;121:73–80. Crossref, Medline, Google Scholar
- 8 . Genetic modifiers of lung disease in cystic fibrosis. N Engl J Med 2005;353:1443–1453. Crossref, Medline, Google Scholar
- 9 . Risk factors for rate of decline in forced expiratory volume in one second in children and adolescents with cystic fibrosis. J Pediatr 2007;151:134–139. Crossref, Medline, Google Scholar
- 10 . CFTR genotype as a predictor of prognosis in cystic fibrosis. Chest 2006;130:1441–1447. Crossref, Medline, Google Scholar
- 11 . Evaluation of scoring system of the chest radiograph in cystic fibrosis: a collaborative study. AJR Am J Roentgenol 1980;134:1195–1198. Crossref, Medline, Google Scholar
- 12 . Cystic fibrosis: a system for assessing and predicting progression. AJR Am J Roentgenol 1998;170:1067–1072. Crossref, Medline, Google Scholar
- 13 . Cystic fibrosis: predictors of accelerated decline and distribution of disease in 230 patients. AJR Am J Roentgenol 1998;171:1311–1315. Crossref, Medline, Google Scholar
- 14 . Correlation of sweat chloride concentration with classes of the cystic fibrosis transmembrane conductance regulator gene mutations. J Pediatr 1995;127:705–710. Crossref, Medline, Google Scholar
- 15 . Afg352 is a major determinant of charge selectivity in the cystic fibrosis transmembrane conductance regulator chloride channel. Biochemistry 1999;38:5528–5537. Crossref, Medline, Google Scholar
- 16 . Changes in the normal maximal expiratory flow volume curve with growth and aging. Am Rev Respir Dis 1983;127:725–734. Medline, Google Scholar
- 17 . CF: an x-ray database to assess effect of aerolized tobramycin. Pediatr Pulmonol 2004;38:23–30. Crossref, Medline, Google Scholar
- 18 . Chest radiographs for outcome assessment in cystic fibrosis. Proc Am Thorac Soc 2007;4:302–305. Crossref, Medline, Google Scholar
- 19 . Regression methods in biostatistics: linear, logistic, survival and repeated measures models. New York, NY: Springer, 2005; 253–289. Google Scholar
- 20 . Random-effects models for longitudinal data. Biometrics 1982;38:963–974. Crossref, Medline, Google Scholar
- 21 . Cystic fibrosis mutations and genotype-pulmonary phenotype analysis. J Cyst Fibros 2006;5:33–41. Crossref, Medline, Google Scholar
- 22 . Detecting early structural lung damage in cystic fibrosis. Pediatr Pulmonol 2002;34:228–231. Crossref, Medline, Google Scholar
- 23 . Scoring systems for CT in cystic fibrosis: who cares? Radiology 2004;231:296–298. Link, Google Scholar
- 24 . High-resolution computed tomography of the chest in children with cystic fibrosis: support for use as an outcome surrogate. Pediatr Radiol 1999;29:731–735. Crossref, Medline, Google Scholar
- 25 . Relationship between the chest radiograph, regional lung function studies, exercise tolerance, and clinical condition in cystic fibrosis. Arch Dis Child 1981;56:106–111. Crossref, Medline, Google Scholar
- 26 . Cystic fibrosis: when should high-resolution computed tomography of the chest be obtained? Pediatrics 1998;101:908–913. Crossref, Medline, Google Scholar
- 27 . Pulmonary outcome in cystic fibrosis is influenced primarily by mucoid Pseudomonas aeruginosa infection and immune status and only modestly by genotype. Infect Immun 1999;67:4744–4750. Crossref, Medline, Google Scholar
Article History
Received March 9, 2009; revision requested April 20; revision received June 9; accepted June 19; final version accepted June 24.Published in print: Dec 2009