Explaining some terminology…
Half the battle with learning about genetics is understanding the terms. It can be a bit like learning a few words in a foreign language.
When you start learning about genetics, you will see “SNP” used a lot. (People usually say “snip” for this acronym.)
SNP stands for ‘single nucleotide polymorphism’. This simply means that one nucleotide in a gene is different from what is typically found in that spot in the sequence.
Wait – what are nucleotides?
Nucleotide bases are the A, C, G, and T’s found in your DNA results.
“A” stands for adenine, C for cytosine, G for guanine, and T for thymine – these are the nucleotide bases that make up DNA.
Your DNA is made up of more than 3 billion pairs of these nucleotide bases. (Not all of your DNA codes for genes… later lesson!)
What happens if a change occurs in your DNA?
Within a gene, if the typical DNA strand calls for an A and you have a G, then this is a change in the DNA that may (or may not) affect the protein that it codes for.
This would be considered a ‘single nucleotide‘ change.
If that change is fairly common, it is called a ‘polymorphism’. Technically, polymorphism means a change found in 1% or more of the population.
Thus, SNP = single nucleotide polymorphism = a change in one A/C/G/T that is somewhat common
What about mutations?
Mutation is another way of stating that a gene has changed. In research, scientists use the word mutation when the genetic change is found in less than 1% of the population.
Thus, mutations are somewhat rare changes while polymorphisms are more common changes.
Why do Genetic Lifehacks articles refer to everything as a genetic variant?
Variant is more of a catch-all term, meaning there is a change. This change could be a SNP, a mutation, or that a bit of code is inserted or deleted into the gene. In general, most of the variants on this website are SNPs.
- AA: Alcohol flush reaction[ref], decreased risk of alcohol dependency
- AG: Alcohol flush reaction, decreased risk of alcohol dependency
- GG: typical acetaldehyde metabolism
To recap:
- SNP = single nucleotide polymorphism
- Polymorphisms are changes occurring in more than 1% of the population
- SNPs may – or may not – cause changes to the way the protein functions
- Mutations are changes in a gene. This term is usually used for changes found in less than 1% of the population