Dictionary of genetics and related terms

Click on a term below to see an explanation of what it means.

Do let us know if there are any explanations missing for terms or concepts used on this website, we might be able to include them in our dictionary. Just send an e-mail to: fargen@fargen.fo

Base

A base is the part of a nucleotide, which contains genetic information. There are four types of bases: A (Adenine), C (Cytosine), G (Guanine) and T (Thymine). The DNA strands write their messages using these letters. The order of these letters determines our traits. The method used to read these letters is called sequencing (bases and nucleotides).

Bioinformatics

Using data technology to analyse and interpret biological information about, for example, the structure and function of genes.

Carrier (of a genetic condition)

You inherit two copies of each gene from your parents, one from your mother and the other from your father, together they make up a gene pair. Hereditary conditions may occur if you inherit a genetic defect from one or both of your parents. We differentiate between recessive and dominant genes. You are a carrier of a genetic condition if you inherited a recessive gene from one of your parents, in which case your children may inherit the gene from you.

Chromosome

The genetic traits (genes) are located in tightly woven coils of DNA strands called chromosomes. In human beings the DNA strand is divided into 46 chromosomes, divided into 23 pairs. In each pair one chromosome is inherited from the mother and the other from the father, 22 of the pairs are the same in women and men, and the last pair is the sex chromosome. Women have two X chromosomes while men have one X and one Y chromosome.

Disease gene

People often talk about a disease gene, such as the CTD gene. This is not accurate, because everyone has this specific gene, but when someone has a medical condition because of that gene there is a difference in the gene caused by a mutation. The mutation makes the gene not work the way it is supposed to.

DNA

DNA is an abbreviation of deoxyribonucleic acid. The building blocks in DNA are called nucleotides. DNA is made up of two long strands that coil around each other inside the cells. DNA can be considered a gigantic database with information about how proteins should be structured. This information is coded and stored in the genes. A single human cell contains approximately two metres of DNA strands. The way DNA is structured makes it possible for it to be copied with great precision and inherited from generation to generation. This replication ensures that genetic heritage is constantly passed on. The order of the bases in a DNA molecule determines the characteristics of the individual gene.

Dominant genetic condition

You inherit two copies of each gene from your parents, one from your mother and the other from your father, together they make up a gene pair. Hereditary conditions may occur if you inherit a genetic defect from one or both parents. If it is a dominant disease gene, you will have the condition even if you only inherit the faulty gene from one of your parents, because dominant disorders are caused by a single faulty gene (the opposite is true for recessive genetic disorders). One example of a dominant genetic disorder is Huntington’s chorea, which does not exist in the Faroe Islands today.

Gene

A gene is a small segment of the genetic material or DNA strand, which contains information about how a certain protein or parts of a protein should be built. The order of bases/nucleotides determines how the protein is built. A protein’s structure determines how that protein functions. The interplay between proteins determines how we are and what we look like.

Genetic condition or disorder

A genetic condition or disorder is caused by a mutation in a person’s genome. Experts differentiate between monogenic and polygenic conditions. A monogenic condition is caused by a mutation in a single gene. CTD and cystic fibrosis are examples of monogenic disorders. Polygenic conditions or complex conditions, on the other hand, have several different causes at the same time, and the reason can be the state of several different genes coupled with lifestyle and the environment. Examples of polygenic conditions include cardiovascular diseases, diabetes, obesity and mental disorders. Some genetic conditions are inherited (congenital) and others arise from changes or mutations in a gene, which occur later in life (spontaneous mutation). Mutations can happen by chance or be caused by the environment.

Genetics

The area of biology, which is about the structure and function of our genetic material, about biological heritage from parents to children, changes and variations.

Genome

A genome includes all the genetic material (DNA) in a cell. The genome contains approximately 20,000 genes, which, nevertheless, only account for 1 to 5 % of your genome. Although our knowledge is still limited about the rest of the DNA, we know that it plays a decisive part in regulating genes, ensuring that they “switch on” and “switch off” at the right times. The total combined genetic material of human beings is called the human genome.

HUGO - Human Genome Project Organisation

A vast international project, which was the first to map all human genetic material, the entire human genome. The project ran from 1990 to 2003 and was a collaboration between scientists from 17 different countries.

Incidental finding

When a medical examination by chance detects something outside the specific scope of the test, i.e. an incidental result, it is called an incidental finding. Incidental findings may be detected during autopsies, diagnostic examinations, in medical research, as well as in genetic and genome research.

Informed consent

A declaration of consent or informed consent is a concept in law, which is used in areas such as medical research. The purpose of a declaration of consent in research is to ensure that the participants in the research project receive sufficient information about the project and their participation. By law no treatment or test may be carried out without the participant’s consent.

Nucleotide

The DNA molecule looks like two long strings of pearls entwined around each other in a spiral. These pearls, which are the building blocks of the DNA strands, are called nucleotides. The nucleotides are made up of bases and other materials.

Mutation

Major or minor changes can occur in the order of nucleotides in the DNA, they can occur spontaneously or because of some external influence. Such changes happen all the time and sometimes they can cause a gene-related condition.

Protein

A substance, which is everywhere in all beings. Proteins are made up of amino acids and each individual protein has a specific function. In order for proteins to function properly, the order of amino acids usually has to be completely error-free.

Recessive genetic condition or disorder

You inherit one copy of each gene from your parents, one from your mother and the other from your father, together they make up a gene pair. Hereditary conditions can occur if you inherit one genetic defect from either or both of your parents. If it is a recessive disease gene you will only become sick if you inherit the disease gene from both parents. If you only inherit the disease gene from one of them, you will be a carrier of that genetic disorder. One example of a recessive genetic condition is CTD. If two individuals who are both CTD carriers have a child together, there is a 25% probability that the child will have the CTD disorder, a 50% probability that the child will be a CTD carrier and a 25% probability that the child will neither carry nor have the disorder.

Reference genome

A reference genome is an average genome, which is based on data from many different people from the same geographical area. The reference genome represents people in a specific limited area. Two persons from families that have lived in the same area for many generations are likely to have more shared traits in their DNA than two people from areas that are far apart. The reference genome can be used as a reference or basis for comparison in genetic research of individuals or patient groups.

Responsible Clinician

A responsible clinician is a licensed health care professional associated with the Faroese public health services. The responsible clinician is responsible for a given research project both towards individuals and the authorities. This person is also responsible for ensuring that any information submitted to the Genetic Biobank are correct. The responsible clinician for the FarGen project is: MD Bjarni á Steig, Consultant.

Sequencing

A technology for determine the order of bases in the genome. Sometimes researchers only examine a specific portion of a specific gene (gene testing), and sometimes they examine a whole genome (whole genome sequencing).