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Glossary

A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z

A

Amniocentesis: a test done by taking fluid from the amniotic sac during pregnancy to test for conditions in the fetus.

Allele: one of the possible forms of a gene.

Alzheimer Disease (AD):  the most common form of dementia. Individuals with dementia have a gradual buildup of changes in the brain that affects memory, language, learning, thinking, reasoning, and everyday tasks. Certain types of AD have a known genetic cause, but most cases of AD are caused by a combination of environment and genetics.

Autosomal: a trait or condition you can pass down or inherit and is not affected by your sex, such as Cystic Fibrosis and Sickle Cell Anemia.

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B

Benign variant: a DNA change that does not affect a gene’s function or cause a health problem. We all have many benign variants that make us unique from each other that do not cause medical issues.

Birth defect: a physical abnormality that is present at or before birth.

BRCA1/BRCA2: BRCA1 and BRCA2 are genes that every person has. When they are not working correctly then a person is at an increased risk for breast, ovarian, prostate, pancreas and other cancers. People can inherit a mutation in either of these genes from their mother or father.

Buccal sample: a way to collect DNA from the cells on the inside of a person’s cheek, either through a saliva sample or cheek swab.

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C

Cardiomyopathy: a condition in which part or all of the heart muscle is thicker than normal. This may cause heart rhythm problems, breathlessness, and chest pain, but some people are symptom-free. Certain types of this condition have a known genetic cause.

Carrier: we have two copies of every gene and when one’s not working correctly it would cause an individual to be a carrier of a certain genetic disorder. Being a carrier does not necessarily mean that you or your children will develop a genetic condition.

Carrier testing/screening: a medical test that is typically performed for family planning: helps intended parents know if they are a carrier for inherited genetic conditions and whether their children could be at-risk.

CGC (Certified Genetic Counselor): a credential held by genetic counselors in United States that is received after passing an examination, that demonstrates their skills and knowledge as a health care professional.

Chorionic villus sampling: a test done by taking cells from the placenta in early pregnancy to detect genetic conditions in the fetus.

Chromosome: DNA that is packaged into structures that are found in the cells of living things.  Humans have 46 chromosomes that come in 23 pairs, the first are numbered 1-22, and the last chromosome determines sex, with females being XX and males being XY. 

Congenital: a term that describes a condition or abnormality that is present at birth.

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D

DNA:  the building block of life contained in each of our cells that carries our genetic information. 

Diagnostic testing: a medical test that provides information that allows a physician to diagnose a condition.

DNA testing: a form of genetic test that specifically analyzes DNA. This type of testing may be used to identify DNA changes that can cause disease, or it may be done to learn other genetic information about an individual, such as paternity or ancestry.

Dominant: a form of a gene that, when present, overpowers the alternate (recessive) form.  This is also referred to as the dominant allele.  

Direct access genetic testing: also known as at-home DNA testing or direct-to-consumer (DTC) testing, these are tests that are marketed directly to consumers and enables them to purchase various types of genetic tests and receive the results without the involvement of a personal physician or insurance company. 

Dysmorphic: a term used to describe physical features, particularly facial, that are not usually found in an individual of the same age or ethnic background.

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E

Early Onset Alzheimer Disease: a type of dementia that starts before age 65 and causes a gradual loss of memory and thinking abilities. There are several different genes that can cause early-onset Alzheimer disease, but only a small number of families have a detectable gene change using current genetic tests. Most cases of early onset Alzheimer disease remain unexplained.

Exome: a small part of the full genome. The exome only contains the instructions that go on to make proteins, the components the body needs to grow, develop and function.

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F

Familial: a condition where there is a strong family history, but there is not an identified genetic cause.

Family history: Information about health and medical issues in relatives. Family history is one of the most important tools a genetic counselor uses to identify genetic risk. Patterns of specific health issues in an individual’s family history are useful to determine the risk of disease and appropriate genetic testing options.

Founder mutation/effect: a genetic change observed at a higher rate in a group that is or was geographically or culturally isolated, where one or more of the founders of that group were a carrier of the change.   

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G

Gene: small portions of chromosomes that are inherited and determine characteristics of an individual, such as eye color or whether or not they have certain genetic diseases. 

Gene therapy: an experimental treatment in which a non-working gene is replaced with a working copy of the gene in order to prevent or correct a known genetic disorder. 

Genetic Counselor: a healthcare professional who has training in genetics and counseling who works alongside geneticists, medical oncologists, or other members of your healthcare team. Genetic counselors assess your medical history and family history to determine if you are at risk for a genetic or hereditary condition and discuss the implications of available genetic testing options.

Genetic risk: the contribution our genes play in the chance that we will develop a certain illness or condition.

Genetic testing: analyzing a person’s genetic material (i.e. chromosomes or genes) in order to identify variants.

Geneticist: a doctor who has completed a genetics residency or fellowship and has also passed the medical board certification/examination for genetics. A clinical geneticist evaluates patients at risk for inherited diseases and treats inherited disorders.

Genome: the complete set of genetic information that makes up a person. The genome includes all of a person’s genes, as well as the non-coding areas of DNA found in-between the genes.

Genotype: describes your genetic makeup. This term is usually used when referring to a particular trait. 

Germline modification: a technique that involves changing genes in eggs, sperm, or very early embryos generally for the purpose of avoiding the impact of a known, disease-causing genetic abnormality. The changes will be passed to future generations.

Germline testing: testing typically performed on a blood or saliva sample to look for inherited genetic changes or changes that someone has from birth, which can be passed down from one generation to the next.

Genetic Information Nondiscrimination Act (GINA): a federal law passed in 2008 that protects people from their genetic information being misused and impacting their health insurance coverage or employment. 

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H

Hereditary/Inherited: a condition or disease that can be passed down from one generation to the next.  Inherited conditions are a determined by genetic factors.

Huntington Disease (HD): an inherited disease of the brain that gets worse over time. It can affect a person’s movements, balance, speech, thinking, behavior, and mood.

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I

Informed consent: the process of learning key details about a medical treatment (such as a drug, surgery or test) to be able to decide whether or not to have the treatment or test.  

In vitro fertilization (IVF): the joining of an egg and sperm in a laboratory setting to produce embryos

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L

Likely pathogenic variant:  a DNA change we think likely causes a gene not to work and may lead to a health problem.  

Lynch syndrome: Lynch syndrome or hereditary nonpolyposis colorectal cancer (HNPCC) is the most common form of hereditary colorectal cancer.  People who have a mutation in one of the Lynch syndrome genes have an increased risk for colorectal, uterine and other cancers.

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M

Mitochondrial inheritance: genes located in the mitochondria that are passed from the mother to the child, the father does not pass these down.

Multifactorial conditions: medical conditions caused by multiple genetic contributions in addition to the environment.

Mutation (genetic mutation): a change in DNA from its original state.  Some mutations do not cause any problems, while others result in disease; however, this term is most is often used when an individual has a genetic change that causes a health condition.

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P

Pathogenic variant (also called deleterious variant): a change in the DNA that is known to cause a gene not to work and may lead to a health problem.

Pedigree:  a family tree using established symbols. Genetic counselors use pedigrees to review  the family history and look for patterns that might suggest a risk for genetic disorders or health-related conditions in the family.

Personalized medicine: term used to describe an emerging healthcare approach that tailors disease prevention and/or treatment based on an individual's genes, environment, lifestyle, and other factors. 

Phenotype: describes the features you have as a result of your genotype

Preimplantation genetic diagnosis: screening test performed during in vitro fertilization (IVF) to determine whether specific genetic conditions (such as Down syndrome or cystic fibrosis) are present in embryos.

Protein: the components a person needs to grow, develop and function.

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R

Rare disease: a disease that affects less than 200,000 Americans at any given time.  Note that different countries may use different numbers to describe a rare disease or disorder.

Recessive:  a form of a gene that is masked by the alternate (dominant) form of the gene and is only expressed when the person has two of these non-dominant (recessive) copies. This is also referred to as the recessive allele.  

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S

Sequencing: a test that reads through the DNA code letter by letter to look for changes that can cause health problems. This test can be done on a single gene, a panel of genes, or on all of a person’s DNA instructions (genome or exome).  

Sex-linked: trait or condition tied to the X or Y chromosome.

SNP (single nucleotide polymorphism) testing: testing that looks for single letter changes within the DNA. (This is different than sequencing an entire gene or genome)

Sporadic: usually refers to a condition that happens by chance.

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T

Tumor/somatic testing: testing that is done on cells from a tumor or cancer to look for DNA changes. Knowing the DNA profile of a tumor can help doctors tailor treatment. Most DNA changes found in a tumor are not inherited and not present in a person’s healthy cells.  

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V

Variant: a change in your DNA instructions (like a change in the spelling of a word) that is different than what most people have. It may or may not change the way the gene works.

VUS (Variant of Uncertain/Unknown Significance): a change in the DNA instructions that scientists and doctors are unsure yet if it causes a health problem.

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