Glossary

Genetic and medical terms explained in plain English.

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Finding out more about genetics and healthcare teams can involve lots of jargon and technical words. This is a guide to some of these words and terms to help with understanding.

Genetic terms

Please note that this glossary only includes basic terms relating to genetics.

Term	Explanation
Assay	A test used by scientists, clinicians or researchers to find or measure something, like a chemical or a protein, in a sample.
Autosomes	The set of chromosomes that are present in both males and females. We have 22 pairs of autosomes in almost all of the cells in our body.
Benign variant	A genetic variant that does not contribute to a particular condition. We have thousands of benign and normal variants that are responsible for making us all different.
Biomarker	A sign in the body, like a protein or gene, that can show if something is working as it should, meaning someone is healthy or has a disease.
Blood test	Testing a sample of blood, typically for the diagnosis of illness or to predict the chance of someone developing an illness in the future.
CACNA1C-Related Disorders (CRDs)	A group of rare genetic conditions caused by changes (variants) in the CACNA1C gene, which provides instructions for a calcium channel found throughout the body. These conditions can affect the brain, heart, muscles, and other organs. CRDs vary widely in their features and severity. Some individuals have multisystem involvement, while others may only have neurological or cardiac symptoms.
Carrier	An unaffected individual that carries an alteration in one of their two copies of a gene, usually that is linked to a recessive condition.
Chromosome	Structures of DNA that contain our genetic information, made up of many genes. Humans have 22 pairs of autosomes and one pair of sex chromosomes.
Chromosomal condition (often referred to as a disorder)	A condition caused by an unexpected chromosome change. The chromosome change may have been inherited from a parent, or it may have happened for the first time when a baby was conceived, or during early development.
Clinical trial	Research studies evaluating large groups of people, usually to study the effects of medications or medical devices.
Developmental delay	When a child takes significantly longer to reach certain developmental milestones than would be expected for their age (for example, rolling over, sitting up, walking and talking). Some children might not reach these milestones at all.
Developmental regression	When a child begins to lose previously acquired developmental milestones (for example, they can no longer roll over, sit up, walk or talk).
Diagnosis	Identifying that an individual has a particular health condition by considering their signs and symptoms, and in some cases the findings from diagnostic tests or scans.
Diagnostic odyssey	A term used to describe the journey from initial signs or onset of symptoms through to disease recognition and a final diagnosis.
Diagnostic test	Tests used to gather clinical or genetic information for the purpose of making a diagnosis.
Disorder	There is a clear preference from people living with genetic conditions and their families to use the word ‘condition’ rather than ‘disorder’. We have included the term ‘disorder’ here because it is regularly used by health professionals and in medical literature, because those diagnoses are usually based on a limitation of functional ability.
DNA	The molecule that encodes genetic information. Like an instruction manual, our code is written in DNA.
Dominant condition	Condition caused when one of two copies of a particular gene contain an alteration that stops the gene working correctly.
Frameshift variant	A change in a gene that messes up the flow in how the gene’s instructions are read, like adding a letter that moves all the words in a sentence one letter to the right.
Gain of function variant	A change in a gene that makes it do too much, like the protein it makes works more than it’s supposed to.
Gene	A length of DNA that codes for a certain characteristic.
Gene expression	When a gene is “read” by the cells production machinery and makes its product, like a protein, that the body needs.
Genetic counselling	A service provided by trained healthcare professionals that offers information, support and advice about genetic conditions.
Genetic condition	A condition relating to or involving genes or chromosomes.
Genetic testing	A medical test that can identify an altered gene or chromosome that causes a genetic condition.
Genetics or genomics	The study of genes, genetic variation and inheritance of genetic traits.
Genome	The entire genetic material of an organism.
Genotype	The particular combination of genetic material that an individual has. If the genetic material contains one or more gene changes, this could increase the chance of the individual, or their children, developing a genetic condition.
ICD (implantable cardioverter-defibrillator)	A small device placed under the skin to monitor heart rhythm and deliver a shock if a dangerous arrhythmia (irregular heartbeat) is detected. ICDs are sometimes recommended for people with CACNA1C-related disorders who are at high risk of life-threatening heart rhythm problems.
Loop recorder	A small device placed under the skin to continuously monitor heart rhythms over a long period of time (months or even years). It records heart activity when symptoms occur or when it detects abnormal rhythms. Loop recorders are often used to investigate unexplained fainting, palpitations, or suspected arrhythmias in people with CACNA1C-Related Disorders or other heart conditions. They help doctors gather more information to guide treatment decisions.
Loss of function variant	A detailed examination of inside the body or a part of the body using techniques such as X-ray, ultrasound, computerised tomography (CT) or magnetic resonance imaging (MRI).
Missense variant	A change in a gene that swaps one part of its instructions, leading to a different protein being made.
Multisystemic	A term used to describe conditions that affect more than one organ system in the body. Many CACNA1C-Related Disorders are multisystemic, meaning they may involve the brain, heart, immune system, muscles, or other parts of the body. The severity and combination of symptoms can vary greatly between individuals.
Natural History Study	A study that watches how a disease develops and changes in people over time by following people with it, without trying to treat it.
Nonsense variant	A change in a gene that tells the body to stop making a protein too early, so the protein doesn’t work.
Outcome measure	Something scientists check in a study to see if a treatment is working, like fewer symptoms or better health.
Pathogenic variant	A genetic variant that results in a particular condition.
Phenotype	The way a person looks or functions, which can be influenced by their genes and environment.
Predictive test	Testing used to identify genetic changes linked with a condition before a person shows symptoms.
Proof of concept study	A small study done to show if a new idea or treatment might work before larger tests are done.
Protein	A molecule made by genes that helps the body do things like grow, repair, and stay healthy.
Rare condition	A condition that affects fewer than 1 in 2,000 people.
Recessive condition	Condition caused when two copies of a particular gene contain an alteration that stops the gene working correctly.
Reproductive options	If you or a family member has a serious genetic condition, you may be concerned about the possibility of passing it on to your children. There are reproductive options available to help manage this situation and genetic counselling can help you make informed choices.
Saliva test	Testing a sample of saliva (commonly referred to as spit) to identify markers of a particular condition.
Scan	A detailed examination of inside the body or a part of the body using techniques such as x-ray, ultrasound, computerised tomography (CT) or magnetic resonance imaging (MRI).
Sex chromosomes	The chromosomes that determine your sex, XX in females and XY in males.
Single gene condition (often referred to as a disorder)	A genetic condition caused by only one gene.
Syndrome without a name	(SWAN) Sometimes an individual is suspected to have a genetic condition, but genetic testing has so far failed to identify the change in their DNA that has caused it. Sometimes the change is so rare it has never been seen before, or a change has been found but it is not yet possible to confirm if it has caused their condition (a variant of uncertain significance). These are called undiagnosed conditions or syndromes without a name (SWAN).
Tissue test	The removal of a small amount of tissue which is then analysed in a laboratory to identify a particular condition.
Translational research	Research that takes discoveries from the lab and uses them to create new treatments or ways to help patients.
Ultra rare condition	A condition that affects fewer than 1 in 50,000 people.
Variant	A variant is a change to a gene that could affect how it works. Some changes might not affect the way the gene works at all, other changes could be very significant for a person’s health and lead to a genetic condition.
Variant of uncertain significance	(VUS) Sometimes a variant is found that scientists do not yet understand: it is not clear if the change to the gene is harmless, or if it will lead to a genetic diagnosis in future. There is more to learn about the variant, and we don’t yet have enough information to be sure.
Whole genome sequencing (WGS)	Sequencing of an individual’s entire genome and testing for a wide range of variants in a large number of genes at the same time.
X-linked condition	This type of condition is caused by an alteration in a gene carried in the X-chromosome. If an individual carries this type of gene alteration, their sex (whether they are female or male) may influence how likely they are to develop symptoms, or how severe their symptoms may be.

Healthcare professional titles

Having a genetic condition might mean having to see a number of different healthcare professionals. Here is a guide to their roles.

Term	Role
Allied health professional (AHP)	A term for a health professional who is not a doctor or nurse. For example, physiotherapists, occupational therapists, and speech and language therapists.
Audiologist	A health professional who diagnoses, treats, and helps manage a hearing or balance condition.
Clinical Geneticist	A doctor based in a hospital with advanced training and clinical training in genetics.
Clinical nurse manager	A nurse responsible for the management of a ward or a unit.
Clinical nurse specialist	A nurse who has undertaken specialist training to become an expert in one area of healthcare.
Clinical support worker (or auxiliary nurse)	Assists registered nurses with patient care.
Consultant or Attending	A consultant is a senior doctor who practises in one of the medical specialities and is responsible for overall care. The US equivalent term for this is Attending Physician.
District or Community Nurse	A nurse who looks after patients in the community.
General, Family or Primary Practitioner (GP/ FP)	A doctor based in the community who treats patients with minor or chronic illnesses and refers those with serious conditions to a hospital.
Genetic Counsellor	A health professional trained to provide support, information and advice about genetic conditions.
Genetic Nurse	A registered nurse with a special education and training in genetics.
Health Visitor	A qualified and registered nurse or midwife who has chosen to gain additional training and qualifications. They mainly work in the community with children from birth to five years old and their families.
Learning Disability Nurse	A learning disability nurse helps individuals with developmental or intellectual disabilities to ensure their health needs are met.
Midwife	A qualified health professional who cares for women throughout pregnancy, birth, and during the postnatal period, as well as caring for newborn babies.
Occupational Therapist (OT)	A health professional who promotes health and wellbeing through the use of particular activities as an aid to self-management of a condition. OTs can help individuals with genetic conditions to develop gross and fine motor skills and provide equipment.
Paediatrician (or Pediatrician)	A doctor specialising in the physical, mental and social health of children from birth to young adulthood.
Pharmacist	A health professional who is an expert in medicines and their use. They advise medical and nursing staff and provide information to patients.
Physiotherapist	A health professional who helps people affected by injury, illness or disability through movement and exercise, manual therapy, education and advice. They provide advice on pain management.
Practice nurse	A nurse who works in the community, usually in a GP surgery or local health centre.
Physician Associate	A health professional who works alongside doctors and surgeons providing medical care as an integral part of the multidisciplinary team.
Psychiatrist	A doctor who specialises in mental health.
Psychologist	A health professional dealing with the mind and behaviour.
Specialist consultant	A doctor who has completed advanced education and clinical training in a specific area of medicine.
Speech and Language Therapist	A health professional who addresses speech, language and communication problems. They can also help with issues relating to eating, feeding and swallowing.

Medical specialities

Many doctors and healthcare professionals have expertise in a particular medical speciality. Here is a list and explanation of specialities you may experience.

Term	Speciality
Cardiology	Speciality dealing with conditions of the heart.
Clinical neurophysiology	Speciality dealing with the diagnosis and monitoring of neurological conditions by recording and interpreting electrical signals (for example, in epilepsy, nerve function or sleep disorders).
Dermatology	Speciality dealing with conditions of the skin.
Endocrinology	Speciality dealing with hormones and their effects on the body (for example, conditions such as diabetes).
Gastroenterology	Speciality dealing with conditions of the stomach and intestines.
Genetics	Speciality dealing with diagnosis and management of genetic conditions.
Haematology	Speciality dealing with conditions of the blood.
Immunology	Speciality dealing with conditions of the immune system.
Nephrology	Speciality dealing with conditions of the kidneys.
Neurology	Speciality dealing with conditions of the brain, spinal cord and nervous system. This can include some musculoskeletal conditions.
Obstetrics and gynaecology	Speciality dealing with pregnancy, childbirth, and care for the mother and baby for around the first six weeks after childbirth.
Oncology	Speciality dealing with prevention, diagnosis and treatment of cancers.
Ophthalmology	Speciality dealing with disorders and diseases of the eye.
Orthopaedics	Speciality dealing with bones and muscles.
Otorhinolaryngology	Speciality dealing with conditions of the ear, nose and throat.
Paediatrics (or Pediatrics)	Speciality dealing with children and teenagers.
Pharmacology	Speciality dealing with diagnosis, treatment and prevention of mental health conditions.
Podiatry	Speciality dealing with foot, ankle and lower limbs.
Psychiatry	Specialty dealing with diagnosis, treatment and prevention of mental health conditions.
Radiology	Speciality using medical imaging techniques including x-rays and scans.
Respiratory medicine/ Pulmonology	Speciality dealing with conditions of the respiratory system (breathing) and lungs.
Rheumatology	Speciality dealing with conditions that affect joints, tendons, ligaments, bones and muscles, including many types of arthritis.
Urology	Speciality dealing with conditions of the urinary (commonly known as wee) system.
Vascular	Speciality dealing with the circulatory system (which conveys blood around the body) and lymphatic system (which conveys water and other essentials around the body).

Information from Genomics England

• What is genomic or genetic testing? (podcast and explainer video)
• What is a genome? (podcast and explainer video)
• What is whole genome sequencing? (podcast and explainer video + blog)
• What’s the difference between DNA and RNA? (podcast and explainer video + blog)
• What is a variant of uncertain significance? (podcast and explainer video)
• What is a rare condition? (podcast and explainer video + blog)

Original template created by Genetic Alliance UK and adapted by TSA Scientific Advisory Board .