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Glossary of Rare Diseases

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Age-matched controls

Matching on factors such as age and sex is commonly used in case-control studies. This is usually done to improve study efficiency.


A condition in which there is a deficiency of red cells or of haemoglobin in the blood, resulting in a pale complexion and weariness.


Another name for a painkiller, used to relieve pain.


A skin disease characterised by clusters of dilated blood vessels, thickened skin and warty growths.


Appendicitis is when the appendix swells up and causes pain. When this happens the appendix has to be surgically removed.


A tube in the lower, right-hand part of the abdomen that has no useful function.


An assay is an investigative procedure for assessing or measuring the presence, amount, or functional activity of a target, for example, an enzyme.

Biochemical pathways

Biochemical pathways are the long chains of chemical reactions that take place in the normal operation of living systems.


In medicine, a biomarker is a measurable indicator of the severity or presence of a disease.

Blood protein

Blood proteins, also termed plasma proteins or serum proteins, are proteins present in blood plasma. They serve many different functions, including transport of lipids, hormones, vitamins and minerals in the circulatory system and the regulation of acellular activity and functioning of the immune system.


The small and large intestine.

C1 Inhibitor

The C1 Inhibitor is a blood protein. If the body doesn’t produce enough of it, or if it isn’t working as it should then it can initiate episodes of swelling, the main symptom of HAE.

Central line

A central line is a catheter (a thin tube) that is placed in a vein for long-term use.


Chaperone therapy is one of the latest pharmacological approaches to lysosomal storage diseases. These chaperones are minute molecules that can enter the central nervous system to fix defective proteins.


A thread-like structure that carries the genes in a linear order. Males have an X and Y chromosome and females have two X chromosomes.

Cohort study

Cohort studies are a type of medical research used to investigate the causes of a disease, establishing links between risk factors and health outcomes. Cohort studies are usually forward-looking, meaning they are planned in advance and carried out over a future period of time.

Crohn’s disease

Crohn’s disease is a condition that causes inflammation of the digestive system or gut. Crohn’s can affect any part of the gut, though the most common area affected  is the end of the ileum (the last part of the small intestine), or the colon.


Cerebrospinal fluid (CSF) is a clear, colourless body fluid found in the brain and spine.

CT scan

Short for Computed Tomography Scan, this is an X-ray that shows detailed pictures from inside the body.

DBS (dried blood spots) samples

Dried blood spot testing (DBS) is where blood samples are blotted and dried on filter paper. The dried samples can easily be shipped to a laboratory to be analysed.


A doctor who specialises in the treatment of skin diseases.

Deuterated internal standards

An internal standard in analytical chemistry is a chemical substance that is added in a constant amount to samples. Deuterium is one of these internal standards.


Disulfiram is a drug discovered in the 1920s typically used to support the treatment of chronic alcoholism by producing an acute sensitivity to ethanol.


Enzymes are biological molecules (proteins) that accelerate, or catalyse, chemical reactions in the body.

Enzyme deficiencies

Enzymes are biological molecules (proteins) that accelerate, or catalyse, chemical reactions in the body. If you have an absent enzyme or one that is not working as it should then problems may develop.

Enzyme Replacement Therapy (ERT)

Enzyme replacement therapy (ERT) is a medical treatment where a particular deficient or absent enzyme is replaced. Usually this is done by giving the patient an intravenous (IV) infusion containing the enzyme.  Enzyme replacement therapy does not correct the underlying genetic defect, but increases the concentration of enzyme in which the patient is deficient.


Epilepsy is a condition that affects the brain and causes repeated seizures.

Epileptic encephalopathy (EE) patients

Epileptic encephalopathy describes a group of epilepsy syndromes associated with severe cognitive and behavioural disturbances.

Exome sequencing

A technique for determining the DNA structure for all of the expressed genes in an organism. Expressed genes, or exome genes, are the ‘letters’ of DNA that actually translate into proteins.


When the symptoms of a disease suddenly worsen.

GAGs (glycosaminoglycans)

Glycosaminoglycans (GAGs) are important complex carbohydrates that participate in many biological processes. In Hunter syndrome, an enzyme deficiency interferes with the body’s ability to break down and recycle glycosaminoglycans (gli-ko-sah-mee-no-gli-cans) also known as mucopolysaccharides (mew-ko-pol-ee-sak-ah-rides).


Gastroenterologists are doctors who investigate, diagnose, treat and prevent all gastrointestinal (stomach and intestines) and hepatological (liver, gallbladder, biliary tree and pancreas) diseases.


Something of, relating to, or affecting the stomach and intestines.

Gene therapy

The introduction of normal genes into cells in place of missing or defective ones in order to correct genetic disorders.


A person who traces or studies the descent of people or families.

Genetic counselling

Genetic counselling is when patients or relatives at risk of an inherited disorder are advised of the consequences and nature of the disorder, the probability of developing or transmitting it, and the options open to them in management and family planning.


A specialist or expert in genetics.

Genomic sequence data

This is the data gained from whole genome sequencing, the process of determining the DNA structure of a person’s genes.


Your genotype is your complete heritable genetic identity. However, the word genotype can also refer just to a particular gene or set of genes carried by an individual.


This is a particular enzyme. If it’s missing or deficient then fatty molecules called cerebrosides can build up and cause Gaucher disease.


A specialist or expert in haematology, the study of blood and blood forming organs.


A build up of blood, usually clotted, caused by a break in a blood vessel.


An escape of blood from a ruptured vessel.

High-throughput screening (HTS)

High-throughput screening (HTS) is a method for scientific experimentation. Using robotics, data processing, control software, liquid handling devices and sensitive detectors, high-throughput screening allows a researcher to quickly conduct millions of chemical, genetic, or pharmacological tests.

Home therapy

When a disease can be treated in the patient’s own home rather than in a hospital or rehabilitation centre.


An ileostomy is where the small bowel (small intestine) is diverted through an opening in the abdomen. The opening is known as a stoma. A special bag is placed over the stoma to collect waste products that usually pass through the colon (large intestine) and out of the body through the rectum and back passage (anus).


When a liquid substance is inserted into the vein.

Large intestine

Also known as the colon or large bowel, the large intestine comes after the small intestine, it is shorter but much wider than the small intestine and its job is to absorb water from wastes, creating stools.


Refers to something affecting the larynx. The larynx, commonly called the voice box, is an organ in the neck where the vocal cords are located.


Commonly called the voice box, the larynx is an organ in the neck where the vocal cords are located.


A cancer which starts in blood-forming tissue, usually the bone marrow. It causes the over-production of abnormal white blood cells, which are there to defend the body against infection.

Lysosomal biology

Lysosomes are tiny sacs filled with fluid containing enzymes which enable the cell to process its nutrients and destroy the cell after it has died.

Lysosomal storage

Lysosomal storage diseases are rare, inherited, metabolic disorders that result from a defect in the lysosomal function. Lysosomes are tiny sacs filled with fluid containing enzymes which enable the cell to process its nutrients and destroy the cell after it has died.

Mass spec metabolomic study

This is the analysis of protein-protein interactions in small molecules known as metabolites.

Metabolic disorder

Metabolic disorders or diseases are conditions that result in problems with the metabolism. Metabolism is the chemical processes occurring within a living cell or organism that are necessary for the maintenance of life.


Metabolomic is the scientific study of chemical processes involving small molecules known as metabolites.


Short for Magnetic Resonance Imaging, it is a technique used in radiology to form pictures of the inside of the body.

Multiplex UPLC-MS analysis

UPLC-MS stands for ultra performance liquid chromatography – tandem mass spectrometer. It’s a chemistry technique that has very high sensitivity, making it very useful in many applications.

Neuro-cognitive testing

Neurocognitive testing, also known as neuropsychological testing, is a comprehensive evaluation of the patient’s cognitive status by specific neurologic areas, such as: Memory, attention, problem solving, language, visuospatial, processing speed motor, and emotion.


Refers to any disease affecting nerve cells.

Newborn screening

Newborn screening is when newborn babies are tested shortly after birth for a list of conditions that are treatable, but not clinically evident in the newborn period.

Next generation sequencing (NGS)

Next generation sequencing (NGS) describes a DNA technology. Using NGS all the genes in one human can be analysed within a single day.

Orphan conditions

An orphan disease is defined as a condition that affects fewer than 200,000 people nationwide and is another term for rare disease.


A medical practitioner who specialises in children and childhood diseases.


Paediatrics is the branch of medicine that specialises in the medical care of children.

Parkinson’s disease

A progressive disease of the nervous system marked by a tremor, muscular rigidity, and slow, imprecise movement.


Pathogenicity refers to the ability of an organism to cause disease.

Pedigree analysis

Doctors use a pedigree analysis chart to map all family members onto a family tree and work out the probability that someone in the family will inherit a genetic condition.


Your phenotype is a description of your actual physical characteristics.


The final section of the large intestine, it ends at the anus.

Reference ranges

In health-related fields, a reference range or reference interval is the range of values for a physiologic measurement in healthy people, for example, the amount of protein in the blood, or the blood pressure.


A method for identifying the chemical structure of a substance by separating its gaseous ions. Gas phase ion chemistry is a field of science that studies atoms and molecules when they are in the ‘gas’ phase.

Spectrophotometric analysis

Spectrophotometry is a method to measure how much a chemical substance absorbs light. This measurement can also be used to measure the amount of a known chemical substance. Spectrophotometry is one of the most useful methods of analysis in various fields such as chemistry, physics, biochemistry, material and chemical engineering and clinical applications.

Spinal tap

Also known as a Lumbar Puncture (LP), this is a medical procedure in which a needle is inserted into the spinal canal, usually to collect cerebrospinal fluid (CSF) for testing.

Therapeutic concentration range

Refers to either the dosage range, blood plasma or serum concentration usually expected to achieve desired therapeutic effects.

Total parenteral nutrition (TPN)

Parenteral nutrition is the feeding of a person through a vein, bypassing the usual process of eating and digestion.

Type 3 [Gaucher] patients

Gaucher disease has 3 types, type 3 affects roughly 5 % in most Western countries, however in Middle Eastern or Asian countries the % of Type 3 can be much higher.

Ultra-performance liquid chromatography

Ultra performance liquid chromatography is a chemistry technique that has very high sensitivity making it very useful in many applications.


Otherwise known as hives, this skin condition is characterised by a raised, itchy rash.

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