The CF Twin/Sib Study team is conducting a nationwide collection of twins and siblings with CF, sponsored by the Cystic Fibrosis Foundation and the National Institutes of Health. We are obtaining a blood sample from twins, siblings, and their parents, and clinical information from the affected twins and siblings. All information collected will be kept confidential and will be used solely for CF research.
This information will be used to determine which patient symptoms may be attributed to the CF (CFTR) gene and which to other possible genes. It will also be used to study the interaction of genes and environment in CF and the effect this has on disease course.
Who is funding this study?
This study is funded by the Cystic Fibrosis Foundation (CFF) and the National Institutes of Health. Johns Hopkins Medicine is the Coordinating Center, and over 100 CF Centers from the US, Australia, and Great Britain are participating in the recruiting efforts. For more information on the National Institues of Health or the CFF, please see our collection of CF-related links.
What do I have to do?
We ask you or your children to give a blood sample, to answer a few questions, and to have information from you or your children's medical records. This means that investigators from Johns Hopkins Medicine will be reviewing your or your children's medical information. The information will include birth history, medication use, current health status, diagnostic information, growth parameters, pulmonary function data, results of laboratory tests and chest X-rays. The duration of your involvement will include time to obtain the blood sample and to answer personal health, family health, and environmental questions and should take approximately 30 to 40 minutes.
Patients are typically enrolled in the study through their physician; however, we are able to accept direct referrals. CF families who are interested in participating in the study are encouraged to contact us.
A twin study provides a powerful method of determining the contribution of genes to a disease trait. It allows us to ask direct questions about genetic control over symptoms of CF and to search for the genes involved. Twins share both environment and genes. Identical (monozygous) twins have the same DNA from each parent and share 100% of their genes. They also share environment before and after birth. The study of identical twins provides insight into environmental effects on disease and the effects of the interaction of genes with the environment.
Like identical twins, fraternal (dizygous) twins share both the womb environment and the family environment after birth. However, they share, on average, only 50% of their genes. By comparing identical twins with fraternal twins, we can determine the contribution of genes( in addition to or interacting with the CF gene )to differences in patient outcome.
Siblings share on average 50% of their genes and generally share family environment after birth. They help us to further clarify the role of genes and shared environmental factors in the severity of cystic fibrosis. Further, siblings allow us to explore age-related factors. A sib-pair study provides a powerful method of identifying genes contributing to disease. There are far fewer twin pairs with CF than there are sibling pairs, so the addition of sibling pairs enables us to look at symptoms that occur less frequently.
At the completion of the research, we will have more comprehensive knowledge of which CF symptoms are effected by genes and which are influenced more by environment (treatment, diet, etc.). This knowledge will aid CF Researchers and Care Providers in helping to assess risk, and develop/tailor treatments.
Identifying and understanding the differences in transmission of genes from parent to offspring enables us to isolate candidate genes that contribute to the severity of CF disease.