Cancer Genetics

Genetic: Glossary of Terms

Amino Acids: Amino acids are molecules that are the building blocks of proteins. Proteins are a chain of amino acids that fold into a shape and are biologically active to do work within the body. The sequence of amino acids specific to each protein are encoded by specific genes.

Cancer: Cancer is a disease characterized by uncontrolled cell growth. Cancer begins when a single cell mutates, resulting in a breakdown of the normal regulatory controls that keep cell growth in check. These mutations are often caused by aging, but can be inherited, or can be caused by exposure to harmful chemicals.

Cancer Syndromes: Cancer syndromes are caused by inherited genetic mutations in genes that increase susceptibility of developing cancer, often with earlier ages of cancer diagnosis, in the family members who carry or have inherited the mutation.

Carcinogen: A carcinogen is an agent with the capacity to cause cancer in humans. Carcinogens may be natural, such as aflatoxin, which is produced by a fungus and sometimes found on stored grains, or manmade, such as asbestos or tobacco smoke. Carcinogens work by interacting with a cell's DNA and inducing genetic mutations.

Carrier: A carrier is an individual who carries and is capable of passing on a genetic mutation associated with a disease and may or may not display disease symptoms..

Complex Disease: A complex disease is caused by the interaction of multiple genes and environmental factors. Complex diseases are also called multifactorial. Examples of complex diseases include cancer and heart disease.

Epigenome: The term epigenome is derived from the Greek word epi which literally means "above" the genome. The epigenome consists of molecules that modify, or mark, the genome in a way that tells it what to do, where to do it, and when to do it. Different cells have different epigenetic marks. These epigenetic marks, which are not part of the DNA itself, can be inherited from one generation to the next.

Family History: A family history is a record of medical information about an individual and their biological family. Human genetic data is becoming more prevalent and easy to obtain. Increasingly, this data is being used to identify individuals who are at increased risk for developing genetic disorders that run in families.

Gene: A gene is the basic physical unit of inheritance. Genes are passed from parents to offspring and contain the information needed to specify traits and build proteins. Genes are arranged, one after another, on structures called chromosomes. A chromosome contains a single, long DNA molecule, only a portion of which corresponds to a single gene. Humans have approximately 20,000 genes arranged on their chromosomes.

Gene Expression: Gene expression is the process by which the information encoded in a gene is used to direct the assembly of a protein molecule. The cell reads the sequence of the gene in groups of three bases. Each group of three bases (codon) corresponds to one of 20 different amino acids used to build the protein.

Gene Regulation: Gene regulation is the process of turning genes on and off. During early development, cells begin to take on specific functions. Gene regulation ensures that the appropriate genes are expressed at the proper times. Gene regulation can also help an organism respond to its environment. Gene regulation is accomplished by a variety of mechanisms including chemically modifying genes and using regulatory proteins to turn genes on or off.

Gene Therapy: Gene therapy is an experimental technique for treating disease by altering the patient's genetic material. Most often, gene therapy works by introducing a healthy copy of a defective gene into the patient's cells.

Genetic Counseling: Genetic counseling is the professional interaction between a healthcare provider with specialized knowledge of genetics and an individual or family. The genetic counselor determines whether a condition in the family may be genetic and estimates the chances that another relative may be affected. Genetic counselors also offer and interpret genetic tests that may help to estimate risk of disease. The genetic counselor conveys information in an effort to address concerns of the client and provides psychological counseling to help families adapt to their condition or risk.

Genetic Counselor: A specially trained genetic clinician who assesses genetic risk utilizing personal history, family history, and genetic test results and also provides support, education and recommendations for health management, risk reduction, screening, and prevention. A genetic counselor has a specialized graduate degree in clinical genetics and is board certified by the American Board of Genetic Counselors.

Genetic Discrimination: Genetic discrimination is prejudice directed against people who have or may have a genetic disease. Genetic discrimination can involve being denied employment or health insurance. In a healthcare context, it can refer to people being treated based on their genetic status rather than by some more relevant criterion.

Genetic Epidemiology: Genetic epidemiology is a medical discipline that seeks to understand how genetic factors interact with the environment in the context of disease in populations. Areas of study include the causes of inherited disease and its distribution and control.

Genetic Screening: Genetic screening is the process of testing a population for a genetic disease in order to identify a subgroup of people that either have the disease or the potential to pass it on to their offspring.

Genetic Testing: Genetic testing is the use of a laboratory test to look for genetic variations associated with a disease. The results of a genetic test can be used to confirm or rule out a suspected genetic disease or to determine the likelihood of a person passing on a mutation to their offspring. Genetic testing may be performed prenatally, at birth, in childhood or in adulthood depending on the type of genetic disease risk or genetic concern. Ideally, a person who undergoes a genetic test will discuss the meaning of the test and its results with a genetic counselor.

Genome: The genome is the entire set of genetic instructions found in a cell. In humans, the genome consists of 23 pairs of chromosomes, found in the nucleus, as well as a small chromosome found in the cells' mitochondria. Each set of 23 chromosomes contains approximately 3.1 billion bases of DNA sequence.

Genomics: Genomics refers to the study of the entire genome of an organism whereas genetics refers to the study of a particular gene.

Germ Line: The germ line refers to inherited genetic material inherited from the sex cells (eggs and sperm) that pass on genes from generation to generation. Egg and sperm cells are called germ cells, in contrast to the other cells of the body that are called somatic cells.

GINA: The Genetic Information Nondiscrimination Act (GINA) is federal legislation, passed into law on May 22, 2008, that makes it unlawful to discriminate against individuals on the basis of their genetic profiles in regard to health insurance and employment.

Heterozygous: Heterozygous refers to having inherited different forms of a particular gene from each parent. A heterozygous genotype stands in contrast to a homozygous genotype, where an individual inherits identical forms of a particular gene from each parent.

Inherited: An inherited trait is one that is genetically passed down through egg and sperm. Inherited traits are passed from parent to offspring according to the rules of Mendelian genetics. Many traits are not strictly determined by genes, but rather are influenced by both genes and environment

Microbiome: The microbiome is all of the genetic material found within an individual microbe such as a bacterium, fungal cell, or virus.

Molecular Profiling: Tumor molecular profiling is a process of analyzing and evaluating the expression of multiple genes and molecular structures within a tumor (ex DNA, RNA, proteins) in order to further characterize a tumor for the purpose of optimizing the prognosis, treatment and management of cancer.

Mutation: A mutation is a change in a DNA sequence that leads to protein loss or dysfunction. Mutations can be inherited but typically result from aging or exposures to some types of chemicals, radiation and viruses. Germ line mutations occur in the eggs and sperm and can be passed on to offspring, while somatic mutations occur in body cells and are not passed on.

Oncogene: An oncogene is a mutated gene that contributes to the development of a cancer. In their normal state, these genes regulate cell growth.

Pedigree: A pedigree is a genetic representation of a family tree that diagrams the inheritance of a trait or disease though several generations. The pedigree shows the relationships between family members and indicates which individuals have developed disease or carry the trait/s in question.

Personalized Medicine: Personalized medicine is a practice of using an individual's genetic profile to guide decisions made in regard to the prevention, diagnosis, and treatment of disease. Knowledge of a patient's genetic profile can help doctors select the proper medication or therapy and administer it using the proper dose or regimen. Personalized medicine is being advanced through data from the Human Genome Project.

Pharmacogenomics: Pharmacogenomics is a branch of pharmacology applies genetic traits in drug development. An important application of pharmacogenomics is in personalizing individual patient genetic variation with predicting drug responses.

Precision Medicine: Precision medicine is an approach to patient care that allows doctors to select treatments that are mostly likely to treat patients based on a genetic understanding of their disease including cancer. Therapeutic benefit is optimized by using genetic or molecular profiling of disease .

Risk: In the context of genetics, risk refers to the probability that an individual will be affected by a particular genetic disorder. Both genes and environment influence risk. An individual's risk may be higher because they inherit genes that cause or increase susceptibility to a disorder.

Somatic Cell: A somatic cell is any cell of the body except sperm and egg cells. Mutations in somatic cells can affect the individual, and are implicated in the development and treatment of cancer, but they are not passed on to offspring.

Susceptibility: Susceptibility is a condition of the body that increases the likelihood that the individual will develop a particular disease. Susceptibility may be highly influenced by family history and inherited traits but may also be influenced by a combination of genetic and environmental factors.

Tumor Suppressor Gene: Tumor suppressor genes provide the instructions to build proteins that are part of a biological system that regulate cell growth. The tumor suppressor proteins job is to keep cell growth regulated and in check. When the tumor suppressor gene is mutated, the tumor suppressor protein is unable to do its job, and, as a result, unregulated and uncontrolled cell growth may occur, which increases the susceptibility of developing cancer.