Your DNA is a like a long string packed into every cell in your body. Along this string are “bases”, lined up like beads. There are four bases marked by the letters: A, G, C, and T. These align in very speciﬁc sequences to create genes. Your unique genetic makeup is stored in the sequence of these bases.
The sequence formed by these bases varies between people. For example, at a speciﬁc location in a sequence, 75% of the population might have a “G”, while the other 25% may have an “A”. The diﬀerence is only one base, so this type of genetic variation is called a Single Nucleotide Polymorphism or SNP (pronounced “snip”). In this example, the SNP has only two possible variations: “G” or “A”.
You inherit two copies of each gene: one from your mother, and one from your father. In the case of the example SNP above, if you were to carry one of each variant (e.g. “AG”), you would be considered heterozygous for this SNP. If you carried two of the same copies (“GG” or “AA”), you would be homozygous for this SNP. These two-letter designations are your genotype for a specific gene.
To explain a bit further, we can pretend that the gene in the above paragraph is involved in a Vitamin D production. People with the “G” variant might have a version of the gene that produces Vitamin D at a normal rate, while people with the “A” variant might have a copy that produces Vitamin D at a much slower rate. This would mean that people with the “A” version would tend to have less D, which would increase their risk of having chronically low Vitamin D.
Having access to this knowledge can empower people to understand their individual needs, the way they respond to medicines, detox substances, have certain diseases that run in their families, etc… In the above example, someone who knew they had the “AA” genotype could use this information to make lifestyle adjustments to increase their levels if Vitamin D.