Genetic Counseling Terminology

Genetic Counselling Terminology

Use this glossary to explain common terms patients, families, and healthcare professionals may hear when discussing genetic conditions, family history, genetic testing, inheritance, reproductive planning, cancer risk, and personalized care.

Genetic counselling provides information and support to people who have, or may be at risk for, genetic conditions. A genetic counsellor or other genetics professional may review personal and family health history, assess genetic risk, explain testing options and limitations, interpret results, discuss reproductive options, and connect individuals and families with additional care or support. Genetic counselling is a collaborative process that respects each person’s values, culture, preferences, and decisions.

Core concepts and care professionals

Genetic counselling: A process that provides information, risk assessment, emotional support, and guidance related to genetic conditions and genetic testing.
Genetic counsellor: A healthcare professional trained in medical genetics and counselling who helps individuals and families understand genetic information, assess risk, consider testing, and make informed decisions.
Medical geneticist: A physician with specialized training in genetics who evaluates, diagnoses, and manages genetic conditions.
Genetics nurse: A registered nurse with specialized training or experience in genetics who provides education, care coordination, and support.
Genetics professional: A healthcare professional with specialized education and experience in medical genetics, such as a genetic counsellor, medical geneticist, or genetics nurse.
Genetic consultation: A clinical appointment focused on evaluating a possible genetic condition, assessing risk, discussing testing, or planning medical care.
Genetics clinic: A healthcare service where individuals and families can receive genetic evaluation, counselling, testing coordination, and follow-up care.
Genetic condition: A health condition caused in whole or in part by changes in genes, chromosomes, or other parts of the genome.
Inherited condition: A condition caused by a genetic variant that is passed from a biological parent to a child.
Congenital condition: A condition or trait that is present at birth. A congenital condition may be genetic, related to events during pregnancy or birth, or caused by a combination of factors.
Genomic medicine: The use of a person’s genomic information as part of healthcare, including diagnosis, risk assessment, prevention, or treatment planning.
Precision medicine: An approach to healthcare that considers genomic, environmental, lifestyle, and other individual factors when guiding medical decisions.
Patient-centered care: Care that incorporates an individual’s health needs, values, preferences, culture, and informed choices into communication and decision-making.
Family-centered care: Care that includes family members or other support people in communication and decision-making when the individual receiving care wishes.

Family history and risk assessment

Family history: A record of health conditions and significant medical information among a person’s biological relatives, both living and deceased.
Pedigree: A diagram that shows family relationships and the presence or absence of a health condition or trait across generations.
Proband: The person who first brings a possible genetic condition or family pattern to the attention of healthcare professionals.
Index case: Another term for the individual whose condition or test result prompts a genetic evaluation of a family.
First-degree relative: A biological parent, sibling, or child who shares approximately half of a person’s genetic information.
Second-degree relative: A biological grandparent, aunt, uncle, niece, nephew, or grandchild who shares a smaller proportion of genetic information than a first-degree relative.
Affected relative: A biological family member who has a particular condition, trait, or genetic variant being evaluated.
Consanguinity: A biological relationship between partners who share a common ancestor. Consanguinity may increase the chance that both partners carry the same recessive genetic variant.
Genetic risk: The chance that a person may have, develop, or pass on a genetic condition or trait.
Recurrence risk: The chance that a genetic condition or trait may occur again in a family or future pregnancy.
Relative risk: A comparison of the likelihood of a health outcome between two groups. It does not always describe an individual’s absolute chance of developing a condition.
Absolute risk: The likelihood that an individual will develop a condition or experience an outcome within a defined period.
Carrier risk: The chance that a person carries one copy of a genetic variant associated with a recessive or X-linked condition.
Residual risk: The remaining chance that a person has or carries a genetic condition after a genetic test or screening result does not identify the condition.
Penetrance: The proportion of people with a particular genetic variant who show the associated trait or condition.
Variable expressivity: The range of signs, symptoms, or severity that can occur among people with the same genetic condition or variant.
Multifactorial inheritance: A pattern in which multiple genetic factors interact with environmental or lifestyle factors to influence a trait or condition.
De novo variant: A genetic variant that is present for the first time in an individual and was not inherited from either biological parent.
Family communication: The process of sharing relevant genetic or health information with biological relatives who may benefit from knowing it.
Cascade testing: Genetic testing offered to biological relatives after a genetic variant has been identified in a family.

Genes, chromosomes, and genetic variation

DNA: The molecule that stores genetic information and provides instructions used in the development and functioning of an organism.
Gene: A basic unit of inheritance that contains information used to make a functional product, such as a protein or RNA molecule.
Chromosome: A structure made of DNA and proteins that carries genetic information. Most human cells contain 23 pairs of chromosomes.
Genome: The complete set of genetic material in a cell or organism.
Allele: One of two or more versions of a DNA sequence at a particular location in the genome.
Genetic variant: A difference in a DNA sequence. A variant may be harmless, associated with a condition, or have an effect that is not yet known.
Mutation: A change in a DNA sequence. Healthcare professionals increasingly use the term variant because a DNA change may be harmful, harmless, or of uncertain significance.
Pathogenic variant: A genetic variant known to cause or contribute to a condition.
Likely pathogenic variant: A genetic variant considered very likely to cause or contribute to a condition, although the available evidence may not meet the definition of pathogenic.
Variant of uncertain significance (VUS): A genetic variant for which there is not enough evidence to determine whether it affects health. A VUS generally should not be used by itself to make medical decisions.
Benign variant: A genetic variant not expected to cause a health condition.
Likely benign variant: A genetic variant considered very unlikely to cause a health condition, although the available evidence may not meet the definition of benign.
Genotype: The genetic makeup or specific genetic variants present in an individual.
Phenotype: The observable traits, features, or health characteristics of an individual, influenced by genetic and environmental factors.
Locus: A physical location in the genome, such as the location of a gene or genetic variant.
Chromosomal abnormality: A change in the number or structure of chromosomes that may affect health or development.
Aneuploidy: An abnormal number of chromosomes in a cell, such as an extra or missing chromosome.
Copy number variant (CNV): A genetic change involving a difference in the number of copies of a segment of DNA, such as a deletion or duplication.
Mosaicism: The presence of two or more groups of cells with different genetic makeups in the same individual.
Germline variant: A variant in an egg, sperm, or the cells that give rise to them. Germline variants may be passed to biological children.
Somatic variant: A variant that develops in a body cell after conception. Somatic variants are generally not passed to biological children.
Epigenetics: The study of changes that affect how genes are expressed without changing the underlying DNA sequence.

Inheritance patterns

Inheritance: The transmission of genetic information from biological parents to their children.
Autosomal dominant inheritance: An inheritance pattern in which one disease-associated variant on an autosome may be enough to cause a condition. A person with the variant may have a chance of passing it to each child.
Autosomal recessive inheritance: An inheritance pattern in which a person generally needs two disease-associated variants in the same gene, one inherited from each biological parent, to have the condition.
Carrier: A person who has one copy of a disease-associated variant for a recessive or X-linked condition and may pass it to a biological child, often without having the condition themselves.
X-linked inheritance: An inheritance pattern involving a gene on the X chromosome. The effects may differ depending on a person’s sex chromosomes and the specific condition.
Y-linked inheritance: An inheritance pattern involving a gene on the Y chromosome. A Y-linked variant can generally be passed from a biological father to a biological son.
Mitochondrial inheritance: The transmission of genetic information in mitochondrial DNA, which is generally passed through the egg to children.
Sex-linked condition: A condition associated with a gene located on a sex chromosome, usually the X or Y chromosome.
Dominant allele: An allele whose effect may be observed when only one copy is present.
Recessive allele: An allele whose associated trait or condition generally requires two copies to be expressed.
Balanced translocation: A chromosome rearrangement in which genetic material has been rearranged without a substantial overall gain or loss of DNA. A person with a balanced translocation may or may not have related health effects but may have reproductive implications.
Unbalanced translocation: A chromosome rearrangement involving an extra or missing segment of genetic material.
Variable inheritance: A situation in which a condition may follow different inheritance patterns in different families or may be influenced by more than one genetic mechanism.

Genetic testing and screening

Genetic test: A laboratory test that examines DNA, chromosomes, or related genetic material for variants associated with health conditions or traits.
Genetic screening: Testing used to estimate the chance that a person or pregnancy has a genetic condition. Screening does not usually establish a diagnosis by itself.
Diagnostic testing: Testing used to confirm or rule out a suspected genetic condition in a person with signs, symptoms, or a relevant clinical finding.
Predictive testing: Testing used to estimate the chance that a person may develop a genetic condition in the future, often because of a family history or known familial variant.
Presymptomatic testing: Testing for a genetic condition before symptoms appear when a person is known to be at risk.
Carrier screening: Testing to determine whether a person carries a genetic variant associated with a recessive or X-linked condition, often before or during pregnancy.
Newborn screening: Testing performed shortly after birth to identify selected conditions for which early detection and treatment may improve health outcomes. The conditions included vary by jurisdiction.
Prenatal screening: Testing during pregnancy used to estimate the chance that a fetus has a chromosomal or genetic condition.
Prenatal diagnostic testing: Testing during pregnancy used to determine whether a fetus has a specific genetic or chromosomal condition. Examples include chorionic villus sampling and amniocentesis.
Preimplantation genetic testing (PGT): Testing embryos created through in vitro fertilization for selected genetic or chromosomal findings before an embryo transfer.
PGT-M: Preimplantation genetic testing for a specific monogenic condition caused by a variant in one gene.
PGT-SR: Preimplantation genetic testing for structural rearrangements, such as a balanced translocation.
PGT-A: Preimplantation genetic testing for aneuploidy, or an abnormal number of chromosomes.
Pharmacogenomic testing: Testing that examines genetic differences that may influence how a person responds to certain medications.
Tumor testing: Testing genetic changes in tumor cells to help guide cancer diagnosis, prognosis, or treatment. Tumor findings may not be inherited or passed to children.
Germline testing: Testing for genetic variants present throughout the body or in reproductive cells that may be inherited or passed to biological children.
Chromosomal microarray: A laboratory test that looks for extra or missing segments of chromosomes, including many copy number variants.
Karyotype: A laboratory image or analysis of a person’s chromosomes arranged in a standard order to evaluate chromosome number and structure.
Fluorescence in situ hybridization (FISH): A laboratory technique that uses labeled DNA probes to detect a specific DNA sequence or chromosome change.
DNA sequencing: A laboratory method used to determine the order of DNA bases in a gene, group of genes, or larger portion of the genome.
Gene panel: A genetic test that analyzes multiple genes associated with a particular condition, symptom, or group of conditions.
Whole-exome sequencing (WES): A test that analyzes the exons, or protein-coding regions, of many genes across the genome.
Whole-genome sequencing (WGS): A test that analyzes most of the DNA across a person’s genome, including coding and non-coding regions.
Test indication: The medical reason or question that explains why a genetic test is being considered.
Test limitations: Factors that affect what a genetic test can or cannot detect, interpret, or predict.
Informed consent: A process in which a person receives understandable information about a test or procedure, including its purpose, benefits, limitations, possible results, and alternatives, before deciding whether to proceed.

Genetic test results and interpretation

Positive result: A result that identifies a genetic variant or finding relevant to the condition being evaluated. The meaning depends on the test, the variant, and the person’s clinical context.
Negative result: A result that does not identify a relevant finding in the genes or regions examined. A negative result may reduce but does not always eliminate the possibility of a genetic condition.
Inconclusive result: A result that does not provide a clear answer, which may occur because the findings are uncertain, the test cannot resolve the question, or the available information is limited.
Uncertain result: A result involving a variant of uncertain significance or another finding whose health impact has not been established.
Secondary finding: A genetic finding that is unrelated to the original reason for testing but may have medical significance.
Incidental finding: A finding discovered unexpectedly during testing. Some organizations use this term interchangeably with secondary finding, while others distinguish them based on whether the finding was actively sought.
Result interpretation: The process of explaining what a genetic test result may mean in light of the test method, family history, medical history, and current evidence.
Clinical significance: The degree to which a genetic finding is relevant to a person’s health, diagnosis, treatment, screening, or family members.
Reclassification: A change in the interpretation of a genetic variant when new evidence becomes available.
Laboratory report: A document that describes the test performed, findings, interpretation, limitations, and laboratory recommendations.
Genetic information: Information about a person’s genetic makeup, genetic variants, genetic test results, or inherited risk.
Genomic data privacy: The protection and responsible handling of genetic information, including decisions about access, storage, sharing, and future use.
Genetic discrimination: Unequal treatment based on a person’s genetic information or perceived genetic risk. Legal protections vary by country and situation.

Prenatal and reproductive genetics

Preconception counselling: Genetic counselling provided before pregnancy to discuss family history, carrier screening, reproductive options, and possible risks.
Prenatal genetic counselling: Genetic counselling provided during pregnancy to review screening or diagnostic results, family history, ultrasound findings, and available options.
Reproductive options: Choices that may be discussed in the context of genetic risk, including natural conception, donor conception, adoption, prenatal testing, fertility treatment, or choosing not to pursue pregnancy.
Reproductive autonomy: A person’s right to make informed decisions about reproduction according to their own values, circumstances, and preferences.
Maternal serum screening: A blood test during pregnancy that measures selected substances to estimate the chance of certain fetal conditions.
Cell-free DNA screening: A blood-based prenatal screening test that analyzes small fragments of placental DNA circulating in the pregnant person’s blood. It is a screening test and may require diagnostic follow-up.
Chorionic villus sampling (CVS): A prenatal diagnostic procedure that collects a small sample of placental tissue for genetic or chromosomal testing.
Amniocentesis: A prenatal diagnostic procedure that collects a sample of amniotic fluid for genetic, chromosomal, or other testing.
Ultrasound finding: An observation made during an ultrasound examination. Some findings may be associated with genetic conditions, while others may be isolated or have other explanations.
Fetal diagnostic testing: Testing performed during pregnancy to evaluate whether a fetus has a specific genetic or chromosomal condition.
Embryo: An early stage of development after fertilization. In reproductive genetics, embryos created through in vitro fertilization may be considered for preimplantation genetic testing.
In vitro fertilization (IVF): A fertility treatment in which an egg and sperm are combined in a laboratory to create an embryo.
Genetic condition in pregnancy: A genetic or chromosomal condition identified or suspected in a fetus or pregnant person during pregnancy.

Cancer and adult genetics

Hereditary cancer syndrome: An inherited condition that increases the chance of developing certain cancers.
Cancer genetic counselling: Genetic counselling focused on inherited cancer risk, genetic testing, screening, treatment considerations, and family implications.
Familial cancer: Cancer that occurs more often in a family than expected, whether or not a specific inherited genetic variant has been identified.
Tumor genetic testing: Analysis of DNA changes in cancer cells to help guide cancer care. Tumor findings may be acquired during a person’s lifetime and may not indicate inherited risk.
Risk management: A plan to reduce, monitor, or manage the chance of developing a condition based on personal history, family history, genetic findings, and other factors.
Medical surveillance: Ongoing monitoring, screening, or clinical evaluation intended to identify a condition or change at an earlier stage.
Risk-reducing treatment: A medical or surgical intervention intended to lower the chance of developing a condition.
Family testing: Genetic testing offered to biological relatives when a familial genetic finding or condition may have implications for them.
Adult-onset condition: A condition that typically begins or is diagnosed during adulthood, although the age of onset may vary.
Actionable finding: A genetic finding that may lead to a recommended change in medical care, screening, treatment, or prevention.

Support, communication, and follow-up

Psychosocial support: Emotional, social, and practical support that helps a person or family respond to genetic information and healthcare decisions.
Genetic education: Information that helps an individual or family understand genetics, a condition, testing, inheritance, or care options.
Shared decision-making: A collaborative process in which healthcare professionals and the individual or family discuss available options, evidence, preferences, and values.
Informed decision: A decision made after receiving understandable information about the relevant choices, benefits, limitations, and possible outcomes.
Referral: A recommendation or arrangement for evaluation, treatment, testing, or support from another healthcare professional or service.
Care coordination: Organizing communication, appointments, testing, records, referrals, and follow-up among the people involved in care.
Genetic support group: A community or organization that offers information, connection, and support to people affected by a genetic condition or concern.
Culturally responsive care: Care that respects and responds to a person’s culture, language, identity, values, communication preferences, and lived experience.
Language access: Interpretation, translation, or other communication support that helps a person understand and participate in healthcare.
Health equity: The goal of ensuring that all people have a fair opportunity to achieve their best possible health, including equitable access to understandable genetic services.
Follow-up: Additional communication, testing, evaluation, care, or support after a genetic counselling appointment or test result.
Reanalysis: A new review of previously generated genetic data using updated knowledge, databases, or clinical information.
Periodic review: A planned reassessment of personal history, family history, genetic findings, or care recommendations as circumstances and evidence change.

Genetic counselling terminology and recommended services may vary by country, healthcare system, clinical specialty, laboratory, and individual circumstances. Genetic test results should be interpreted with the support of a qualified healthcare professional who can consider the person’s medical history, family history, and preferences.