Sorry I don't understand what you mean by synonymous here
Sometimes 2 or more SNPs are basically the same - they almost always get inherited together as a chunk. In studies, if both synonymous SNPs are included, they'll be seen as having the same impact. VDR Taq and VDR Bsm are another example of this - if you know what someone has in Taq, you can predict what they have for Bsm.
So having the risk version of each is not more significant than having the risk version of just one. But, as seems to be the case of VDR Taq/Bsm, there might be a bigger risk associated with the two synonymous SNPs not being in synch with each other.
That is a good statement. I think it is important to be clear on what is backed up by research, what is unresearched and what is disproven. I am uncomfortable making claims about snps that have no research to back them up, but I am also unsettled by statements that assert snps are irrelevant because there is no research, or that there is no impact on gene function because there is no change in protein.
Without research, I think it's a matter of looking at the odds. What are the odds that a random SNP is having an impact? Quite small - certainly too small to start a treatment designed around a presumed gene dysfunction based on that random SNP.
While I wouldn't object to Yasko saying that "I think Autism patients are helped by doing X, Y, and Z", it's very dishonest to pick a random unresearched SNP on a gene and then describe how that gene functions, and conclude that everyone with a certain version of that SNP needs a certain treatment. She's using those SNPs as an authority upon which the treatment is based, when there is absolutely nothing relevant known about many of those SNPs.
When a synonymous or silent mutation occurs, the change is often assumed to be neutral, meaning that it does not affect the fitness of the individual carrying the new gene to survive and reproduce.
Sorry I wasn't clear ... I meant that the two SNPs are mostly synonymous with each other, not that they create synonymous mutations (which they do, due to the lack of amino acid substitution in the gene).
I agree that synonymous mutations can definitely have an impact, and they often do. It's just usually a lot less serious than the ones with missense and related mutations. Synonymous mutations tend to have a mild impact in functioning (gene might be a percentage point or two "slower" or "faster"). Whereas missense, stop-gain, splice, and insertion or deletion mutations can range between causing no problem at all (such as when there's a missense mutation involving two very similar amino acids), or rare and severe health problems, or death.
It really depends on how it affects the protein made by the gene. A missense mutation might result in the protein breaking down a little faster or a lot faster. Or a stop-gain might result in an essential part of the protein being missing. And then it also depends on how vital that protein is - does it have a mild impact when it's malfunctioning, or is it deadly? Can it be compensated for with a supplement or is it incurable? Does it impact the development of children, or does it manifest in adults?
There's so many variables that it's impossible to predict what any SNP will do, which is why at least some research is necessary before making any assumptions at all. Some of that research can be very basic, such as showing a missense mutation and/or population prevalence. But if there's no mutation and all versions are quite common among healthy people, there's no basis to assume that any version is causing problems.
