Cystic Fibrosis Twin and Sib Study

Johns Hopkins University

 
Educational content
Cystic Fibrosis and Genetics

Cystic Fibrosis

For a video introduction to the lab and about our Cystic Fibrosis research, please click here.

What is cystic fibrosis (CF) and where does it come from? These fundamental questions are answered in our presentation, CF Basics ( Powerpoint | PDF ).

 

Human Genetics

What is the human genome? Find out here (PDF). How did scientists crack the genetic code? Read this history (PDF) to find out.

See this map (PDF) to learn how many variations there are in the cause of CF, and where in the world they are found.

What is a "modifier gene" and what does it mean for cystic fibrosis? ( Powerpoint | PDF ) to learn more.

 

 
Glossary of Terms

Chromosomes

Chromosomes are organized structures of DNA and proteins that are found in cells. A chromosome is a continuous piece of DNA, which contains many genes, regulatory elements and other material.

Gene

A gene is a locatable region of genomic sequence, corresponding to a unit of inheritance, which is associated with regulatory regions, transcribed regions and/or other functional sequence regions.[1][2] The physical development and phenotype of organisms can be thought of as a product of genes interacting with each other and with the environment.

DNA

Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints or a recipe, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.

Allele

An allele (pronounce a-leel) is one member of a pair or series of different forms of a gene. Usually alleles are coding sequences, but sometimes the term is used to refer to a non-coding sequence. An individual's genotype for that gene is the set of alleles it happens to possess.

Gene Mutation

A gene mutation is a permanent change in the DNA sequence that makes up a gene. Mutations range in size from a single DNA building block (DNA base) to a large segment of a chromosome. Gene mutations occur in two ways: they can be inherited from a parent or acquired during a person’s lifetime. Mutations that are passed from parent to child are called hereditary mutations. Mutation is generally accepted by the scientific community as the mechanism upon which natural selection acts, providing the advantageous new traits that survive and multiply in offspring or disadvantageous traits that die out with weaker organisms.

Recessive Inheritance

Both parents carry a normal gene (N), and a faulty, recessive, gene (n). The parents, although carriers, are unaffected by the faulty gene. Their offspring are affected, not affected, or are carriers.

Dominant Inheritance

One parent has a single, faulty dominant gene (D), which overpowers its normal counterpart (d), affecting that parent. When the affected parent mates with an unaffected and non-carrier mate (dd), the offspring are either affected or not affected, but they are not carriers.

Penetrance

Penetrance is a term used in genetics describing the proportion of individuals carrying a particular variation of a gene (an allele or genotype) that also express a particular trait (the phenotype). For example, known mutations in the gene responsible for Huntington disease have 95% penetrance, whereby 5% of those with the dominant allele for Huntington disease don't develop the disease and 95% do. In other word, penetrance is the percentage of individuals with a specific genotype that possess an associated phenotype.

Expression

Gene expression is the process by which inheritable information from a gene, such as the DNA sequence, is made into a functional gene product, such as protein or RNA. Gene regulation gives the cell control over structure and function, and is the basis for cellular differentiation, morphogenesis and the versatility and adaptability of any organism.

Modifier Genes

Modifier genes are genetic variants that affect the clinical manifestation of disease.

Gene Environment Interaction

Gene-environment interaction is a term used to describe any phenotypic effects that are due to interactions between the environment and genes. Naive nature versus nurture debates assume that variation in a given trait is primarily due to either genes, or the individual's experiences. The current scientific view is that neither genetics nor environment are solely responsible for producing individual variation, and that virtually all traits show gene-environment interaction.

Candidate Genes

A candidate gene is a gene, located in a chromosome region suspected of being involved in the expression of a trait such as a disease, whose protein product suggests that it could be the gene in question. A candidate gene can also be identified by association with the phenotype and by linkage analysis to a region of the genome.

Genome Wide Association Studies (GWAS)

A genome-wide association study is defined as any study of genetic variation across the entire human genome that is designed to identify genetic associations with observable traits (such as blood pressure or weight), or the presence or absence of a disease or condition. Whole genome information, when combined with clinical and other phenotype data, offers the potential for increased understanding of basic biological processes affecting human health, improvement in the prediction of disease and patient care, and ultimately the realization of the promise of personalized medicine. a genome-wide association study is defined as any study of genetic variation across the entire human genome that is designed to identify genetic associations with observable traits (such as blood pressure or weight), or the presence or absence of a disease or condition. Whole genome information, when combined with clinical and other phenotype data, offers the potential for increased understanding of basic biological processes affecting human health, improvement in the prediction of disease and patient care, and ultimately the realization of the promise of personalized medicine.

Stochastic Events

Stochastic is synonymous with "random." The word is of Greek origin and means "pertaining to chance”.

Statistical Analysis

Statistics is a mathematical science pertaining to the collection, analysis, interpretation or explanation, and presentation of data. It is applicable to a wide variety of academic disciplines, from the natural and social sciences to the humanities, and to government and business.

Protein

Proteins are large organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by a gene and encoded in the genetic code.

SNPs

Single Nucleotide Polymorphism, or SNP (pronounced "snip"), is a small genetic change, or variation, that can occur within a person's DNA sequence. The genetic code is specified by the four nucleotide "letters" A (adenine), C (cytosine), T (thymine), and G (guanine). SNP variation occurs when a single nucleotide, such as an A, replaces one of the other three nucleotide letters—C, G, or T.

 
Genotyping
To learn more about the genotyping of patient samples, click here (PDF).
 
How genetics changes patient care
What is a "SNP" (pronouced "snip") and why are they important to the understanding and treatment of diseases? Find out here (PDF).
 
Publications

 

Our work has been featured in prominent scientific journals, with a selection of those publications listed here:

 
Presentations

 

Our CF researchers have delivered presentations at prominent international scientific conferences. You can view their slides and listen to their talks by using the links below.

The 21st Annual North American CF Conference (2007 NACFC)

The 22nd Annual North American CF Conference (2008 NACFC)

(Click on the PDF to view the slides and listen along with the MP3)

  • Dr. Garry Cutting - Finding Genetic Modifiers of CF Lung Disease Using Genome-Wide Linkage  PDF |MP3
  • Dr. Juan Celedon - Genome Wide Association Studies: Brief Overview and Application to Asthma  PDF | MP3
  • Dr. Scott Blackman -Genetic Influences on Body Mass Index in CF  PDF | MP3
  • Dr. Vishal Doshi - CAST as a Genetic Modifier of CF  PDF | MP3


The 23rd Annual North American CF Conference (2009 NACFC)

(Click on the PDF to view the slides and listen along with the MP3)

  • Dr. J. Michael Collaco - Contribution of Environment and Genes to Lung Function  PDF | MP3
  • Dr. Scott Blackman - Genome Wide Variants for CF Related Diabetes  PDF | MP3
  • Dr. Lindsay Henderson - MSRA Gene Haplotypes and Meconium Ileus  PDF | MP3


The 24th Annual North American CF Conference (2010 NACFC)

(Click on the PDF to view the slides and listen along with the MP3)

  • Dr. Garry Cutting - Genetic Impact on Disease Severity: What is Clinically Meaningful  PDF | MP3
  • Dr. J. Michael Collaco - Ambient Temperature Associated with Variation in CF Lung Disease  PDF | MP3
  • Dr. Scott Blackman -  CF-Related Diabetes and Type 2 Diabetes: Different on the Outside, Similar on the Inside?  PDF | MP3
  • Dr. Patrick Sosnay - Assessing Disease Liability of Missense CFTR Mutations Using Differing Percentages of Wild-type Function  PDF | MP3
  • Dr. Neeraj Sharma - An Internal Motif of CFTR Enhances EBP50/NHERF Multimerization and Modulates Localization of CFTR  PDF | MP3


 
CF and Genetics Links

There are many resources available on line for people interested in learning more about genetics. Below are some of the links to sites that we think are most helpful:

This National Library of Medicine site discusses genetic disorders from A to Z and has internal links to concepts and tools to help you understand some basics of human genetics.

This link is also directed to the National Library of Medicine website, but it focuses more specifically to information about genetic mutations and their affect on health.

This link directs you to the National Human Genome Research Institute's web page on Cystic Fibrosis. It contains additional resources/links if you are interested in policy, or similar content.

This link is sponsored by the Dolan DNA learning center. It is rich with information and graphics on CF, but will also link you to "DNA from the Beginning" which has wonderful content on the basics of genetics.

 

Information and Support for People with CF

Some links for adults with CF who are seeking information and support.


Below are websites that contain general information about CF for all interested in the disease. These pages may also include support links, and additional education about the condition.

 

General Information regarding Genetics

 

Related Links

 

CF TwinSib Study in the News:

Secondhand Smoke Worsens Lung Function in Cystic Fibrosis Patient

 

Newsflash

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

 

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