Cystic Fibrosis Twin and Sib Study

Johns Hopkins University

Welcome to the Cystic Fibrosis Twin and Sibling Study
DNA Double Helix


Welcome to the website of the Johns Hopkins Cystic Fibrosis Twin and Sibling Study.

Announcement: As of March 31, 2013, the CF Twin and Sibling Study has completed recruitment.  Analysis is ongoing, but enrollment into the study has ended.

In late 2000, Garry Cutting MD, a pediatrician and geneticist at Johns Hopkins Medicine in Baltimore, gathered a research team to discuss the feasibility of searching for genes – other than CFTR - that alter the course of cystic fibrosis. The CF Twin and Sibling Study began in 2001 with Johns Hopkins Medicine as the Coordinating Center. With the support of the CF Foundation and the National Institutes of Health, the project goal was to recruit every CF twin pair and sibling set living across the U.S. The study would gather information about their diagnosis, clinical course, growth and pulmonary disease, to determine the participant’s "phenotype" (clinical picture). Blood samples were also collected and the "genotypes" (genetic code) that were associated with their clinical picture were compared. Details about the family environment could identify certain things like second hand smoke or inconsistent therapies as influences in overall severity. The overall goal of the study is to identify modifiers of cystic fibrosis severity and develop treatments or preventions.

Thanks to the efforts of participating CF Centers (over 100 in the U.S.) and families from America, Australia, Israel, and Great Britain, over 3,400 parents, twins and siblings participated in this project. Work is ongoing to identify modifiers and develop treatments (view our publications).

The CF Twin and Sibling Study is grateful for the sponsorship of the National Institutes of Health and the Cystic Fibrosis Foundation.

Video Introduction

To see our laboratory and get introduced to our studies, click here for a video hosted by the Director of our center, Dr. Garry Cutting.



Want to learn about new and future research studies? Click here to find out what we're up to.

Study Sponsors

Johns Hopkins Medicine and The Johns Hopkins Hospital


National Institutes of Health


Cystic Fibrosis Foundation