Glossary - Main concepts of Genetics

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In this article you will find concepts of genetics that will help you to understand our genetic test.

What is DNA?

DNA (deoxyribonucleic acid) is the biological molecule that contains the genetic information of all living beings. DNA is found mainly in the nucleus of cells. It is composed of a series of units called nucleotides. Each of which contains a nitrogenous base (adenine (A), guanine (G), cytosine (C) or thymine (T)). This molecule coils together to form a spiral structure known as a double helix.

Scientific monkey with DNA

The specific sequence of these bases is what determines the genetic information. DNA is essential for cell replication and gene expression. This allows cells to divide and differentiate to form the different tissues and organs of the body.


Chromosomes are structures found in the nucleus of cells and contain genetic information (compacted DNA). Humans have 46 chromosomes, organized in 23 pairs. Each member of each pair is inherited from the mother and the other from the father. These chromosomes contain the genetic instructions for the development, function and reproduction of all living organisms. They are normally only visible through a microscope during the process of cell division. Chromosomal abnormalities, such as aneuploidy (an abnormal number of chromosomes) and structural abnormalities, can cause genetic disorders and certain types of cancer.

What are genes?

Genes are segments of DNA that contain heritable information for the development of specific characteristics in living beings. Each gene is responsible for the production of one or more specific proteins or other molecules with other functions within the body. Genes are located on chromosomes, and there are currently more than 23,000 genes.

SNPs or polymorphic variants

SNP (Single Nucleotide Polymorphism) is a genetic variation in which a single DNA base or nucleotide has been altered at a specific location in the DNA. SNPs are the most common forms of genetic variation in humans. They are found in approximately every two base pair of human DNA. These changes can affect gene expression, protein structure, enzyme activity and the body's response to certain substances. SNPs can be used to track inherited diseases, as they are often associated with certain genetic disorders. Diabetes, hypertension, cancer and heart disease are some examples. Translated with (free version)

What is a SNP or polymorphic variant?

Genetic association studies - GWAS

GWAS (Genome-wide association study) is an approach to identify those genetic variants associated with an increased risk of a disease or characteristic. The objective is to look for statistical associations between genetic variants in a large number of individuals who have a characteristic (e.g. disease) and those who do not.

Genetic association studies (GWAS) - Example

In a GWAS study, the frequency of each genetic variant is analyzed in a group of people who have the disease or trait in question and in a group of people who do not have that disease or trait and are considered as the control group. Geneticists look for generally polymorphic variants that are more frequent among people with the disease or trait in question compared to people without that disease or trait. GWAS studies are an important tool for identifying polygenic variants associated with a variety of diseases and traits.

Polygenic risk

Polygenic risk refers to the contribution of multiple genetic variants to the risk of a disease. Unlike single-risk genetic variants, which have a large effect on the risk of a disease, polygenic variants have a small individual effect but their combination can have a significant impact on overall risk. For example, a person may have several genetic variants that contribute to the risk of type 2 diabetes, each of which has a small effect on risk, but when combined, the person's total risk is significantly higher than if they only had one of these variants.

How to interpret my results - Normal distribution

Your results score is a score relative to your reference population assuming a Normal distribution of results.

The normal distribution, also known as the Gauss distribution, is one of the most common probability distributions in statistics. It is a continuous distribution that is characterized by its bell-shaped shape, with a peak in the middle and a symmetry around the mean. The normal distribution is defined by two parameters, the mean (μ) and the standard deviation (σ).

The mean represents the central value of the distribution, while the standard deviation indicates the variability or dispersion of the data around the mean. 68% of the values are within one standard deviation of the mean, 95% within two standard deviations, and 99.7% within three standard deviations.

Normal distribution in genetics

In genetics, normal distribution is used to model certain aspects of genetic variability. For example, in a GWAS study, statistical associations are looked for between genetic variants and a disease or characteristic. Once genetic variants associated with disease risk have been identified, a normal distribution is used to model the distribution of genetic risk values in a population.

Polygenic risk - Normal distribution.  - ADNTRO

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