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Genetic Modifiers of Cystic Fibrosis: Sibling Study

This study has been completed.
National Heart, Lung, and Blood Institute (NHLBI)
Information provided by (Responsible Party):
Johns Hopkins University Identifier:
First received: May 20, 2002
Last updated: August 29, 2016
Last verified: August 2016
The purpose of this study is to identify modifier genes in cystic fibrosis (CF).

Lung Diseases
Cystic Fibrosis

Study Type: Observational
Study Design: Observational Model: Family-Based
Time Perspective: Retrospective
Official Title: Genetic Modifiers of Cystic Fibrosis: Sibling Study

Resource links provided by NLM:

Further study details as provided by Johns Hopkins University:

Primary Outcome Measures:
  • Variation among genes in siblings with cystic fibrosis as assessed by DNA [ Time Frame: Single collection ]

Biospecimen Retention:   Samples With DNA
Blood samples

Enrollment: 3459
Study Start Date: September 2001
Study Completion Date: February 2013
Primary Completion Date: February 2013 (Final data collection date for primary outcome measure)
Detailed Description:


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.


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.


Ages Eligible for Study:   up to 100 Years   (Child, Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Probability Sample
Study Population
Siblings with cystic fibrosis

Inclusion Criteria:

  • Diagnosis of CF
  Contacts and Locations
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Please refer to this study by its identifier: NCT00037778

United States, Maryland
Johns Hopkins University
Baltimore, Maryland, United States, 21287
Sponsors and Collaborators
Johns Hopkins University
National Heart, Lung, and Blood Institute (NHLBI)
Principal Investigator: Garry Cutting Johns Hopkins University
  More Information

Responsible Party: Johns Hopkins University Identifier: NCT00037778     History of Changes
Other Study ID Numbers: 1178
R01HL068927 ( US NIH Grant/Contract Award Number )
Study First Received: May 20, 2002
Last Updated: August 29, 2016

Additional relevant MeSH terms:
Cystic Fibrosis
Lung Diseases
Pathologic Processes
Pancreatic Diseases
Digestive System Diseases
Respiratory Tract Diseases
Genetic Diseases, Inborn
Infant, Newborn, Diseases processed this record on April 21, 2017