Your genome – your body’s complete set of genetic material – is made up of more than six billion units (nucleotides) of DNA divided across 46 chromosomes.
The sequence of these units is important. Your body uses sections of DNA (genes) to make proteins and other molecules that it needs to function. Each set of three bases in a gene corresponds to a particular amino acid – when your body reads the sequence of a gene, the corresponding amino acids are assembled into a chain to make a protein.
Differences in your DNA sequence contribute to your individuality, and also affect the way your body functions. These differences are known as variants.
Variants in genes can change the product that is made – they might cause the gene to produce a non-functioning protein, or sometimes no protein at all.
Variants can be inherited from your parents, or arise when DNA is copied as your cells divide. Most are harmless, but some can cause or increase your risk of diseases.