Clinical trial NCT00037778: Genetic Modifiers of Cystic Fibrosis: Sibling Study
Official title: Genetic Modifiers of Cystic Fibrosis: Sibling Study
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Lung Diseases
Cystic Fibrosis
Lead sponsor: Johns Hopkins University
Sponsor class: OTHER
Collaborators: name: National Heart, Lung, and Blood Institute (NHLBI)
First posted: 2002-05-21
Enrollment: 3459
Sex: ALL
Maximum age (years): 100
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: FAMILY_BASED
Time perspective: RETROSPECTIVE
Sampling method: PROBABILITY_SAMPLE
Study population: Siblings with cystic fibrosis

Brief summary: The purpose of this study is to identify modifier genes in cystic fibrosis (CF).

Detailed description: BACKGROUND:

CF is a highly variable but inevitably fatal single gene disorder. Several lines of evidence suggest that genetic background contributes to the variability of cystic fibrosis phenotypes. The study will develop CF as a model for the identification of modifier genes by capitalizing on the availability of a large motivated population of affected twins and siblings.

The study is in response to a Request for Applications titled "Genetic Modifiers of Single Gene Defect Diseases" released in August 2000 and co-sponsored by the National Institute of Diabetes, Digestive, and Kidney Diseases.

DESIGN NARRATIVE:

The study has four aims: 1. To identify heritable CF phenotypes by twin study. Intrapair and interpair variance will be determined for selected CF phenotypes, and interclass correlations (monozygotic versus dizygotic) will be performed to identify CF phenotypes with a substantial heritable component. 2. To determine the contribution of genetic and other factors to the variability of CF phenotypes by analysis of affected sibs. Variance component methods will be used to evaluate the CF phenotypes that appear to be heritable based upon other studies or the results of aim 1. 3. To identify biologic phenotypes that correlate with heritable CF phenotypes by clinical study of twins and sibs. Multivariate analysis will be used to find biologic phenotypes associated with CF phenotypes. 4. To identify modifier genes and loci responsible for heritable CF phenotypes by linkage approaches. Identity by descent and transmission disequilibrium methods will be used to test linkage between candidate genes/loci and heritable CF phenotypes. To identify novel loci, genome-wide scans will be performed upon sib pairs selected for extreme concordance or discordance for heritable traits.

Eligibility criteria: Inclusion Criteria:

* Diagnosis of CF

Primary outcomes:
measure: Variation among genes in siblings with cystic fibrosis as assessed by DNA
timeFrame: Single collection
Secondary outcomes:
Other outcomes:
Locations:
city: Baltimore
country: United States
facility: Johns Hopkins University
state: Maryland
Study officials:
affiliation: Johns Hopkins University
name: Garry Cutting
role: PRINCIPAL_INVESTIGATOR
References:
citation: McWilliams R, Hoover-Fong J, Hamosh A, Beck S, Beaty T, Cutting G. Problematic variation in local institutional review of a multicenter genetic epidemiology study. JAMA. 2003 Jul 16;290(3):360-6. doi: 10.1001/jama.290.3.360.
citation: Groman JD, Hefferon TW, Casals T, Bassas L, Estivill X, Des Georges M, Guittard C, Koudova M, Fallin MD, Nemeth K, Fekete G, Kadasi L, Friedman K, Schwarz M, Bombieri C, Pignatti PF, Kanavakis E, Tzetis M, Schwartz M, Novelli G, D'Apice MR, Sobczynska-Tomaszewska A, Bal J, Stuhrmann M, Macek M Jr, Claustres M, Cutting GR. Variation in a repeat sequence determines whether a common variant of the cystic fibrosis transmembrane conductance regulator gene is pathogenic or benign. Am J Hum Genet. 2004 Jan;74(1):176-9. doi: 10.1086/381001. Epub 2003 Dec 18.
citation: Boyle MP. Nonclassic cystic fibrosis and CFTR-related diseases. Curr Opin Pulm Med. 2003 Nov;9(6):498-503. doi: 10.1097/00063198-200311000-00009.
citation: Hefferon TW, Groman JD, Yurk CE, Cutting GR. A variable dinucleotide repeat in the CFTR gene contributes to phenotype diversity by forming RNA secondary structures that alter splicing. Proc Natl Acad Sci U S A. 2004 Mar 9;101(10):3504-9. doi: 10.1073/pnas.0400182101. Epub 2004 Mar 1.