the letters are pretty meaningless in themselves astro
its a deep subject - but the letters just stand for the 4 different nucleic acids that DNA code is made up from - the language its written in if you like
adenine (A), guanine (G), cytosine (C), and thymine (T).
details here
https://tinyurl.com/y2vqs9aka
Geneis a section of DNA that is known to do something specific - usually to code for a specific protein to be made in the body - usually hundreds or thousands of nucleic acids long
Alleles are different forms of any particular gene that occur as a result of evolution or mutation
at any given time a population of animals or humans will have one or many alleles (versions) of all genes
these alleles may be different from one another by one single nucleic acid pair (DNA is double helix - 2 matched chains of DNA bonded together like a spiral ladder - and when one acid is changed - its mate needs to be changed accordingly ) - or by several nucleic acid pairs
a single nucleic acid pair or
SNP is this smallest unit of DNA - that is often referred to when a single pair is mutated / or different to the most common wild allele - eg on 23andMe reports
the above is all nice and straightforward
some of the tricky bits are:
1, 90% of genetic testing just reports if a gene is the expected type of mutated - unless the exact mutation is known and categorised by previous experiments - no one knows for sure if a given SNP is helpful or harmful (better or worse than the wild type) to any given individual
2, genes are far from the whole story - genes on their own merely hold the code for the body to use when they are needed - most genes are switched off most of the time - for example: were needed while we were growing in the womb - but not needed - or needed to a tiny fraction of this level - in adults.
what determines how much a gene is turned on is
Epigenetics - this is what really controls the process of actually putting the genes to work.
epigenetic regulation and modulation processes have feedback loops and can often compensate for genes that are not quite so good as say a wild type.
epigenetic transcript
ion regulation can turn a gene on from 0 to 1000's of times greater than nominal in many cases
as a result the public has been oversold on the technology of gene testing by companies like 23andMe - who want to appeal to peoples need for black and white answers - so they present their data as if Genes are the whole story - when in fact genes are only a part of the story and epigenetics is a far bigger factor in most cases. 23andMe cannot test that though - so they neglect to mention this fact.
And people in general love absolutes and tend to buy in with a retrospective logic that often makes them feel better about
themselves - eg "I have cardio vascular disease because my 23andme says my genes predispose me to it - there's nothing i can do" ( which feels a whole lot better than "i eat 3 take outs a week, plus gallons of fizzy pop and total lack of exercise and i just cant be bothered to change").
in fact in many many cases the effects of say environment or diet or lifestyle can swamp the effects of any given gene allele.
that's why so many studies find only say around a 20% component of so many disease risks are genetic.
this is all general by the way - clearly there are some gene mutations that can be pretty much 100% of disease risk - like some clotting disorders etc - and this is what makes it so confusing to people.
Post Edited (Garzie) : 1/15/2023 10:29:09 AM (GMT-8)