DNA test

[Marybrown06]

Hey, I would like to take a DNA test.

Is there a gene linked to B12 or PA to look at in the results?

Which brand of DNA test would you advise in order to get all medical raw data?

[fbirder]

Yes, there is a gene, or genes, that are responsible for PA. No, nobody knows exactly which ones they are. Even if they did then a test would only show that you have a propensity to PA, not that you will definitely suffer from it.

There are other genes that are involved with B12, but the only confirmed conditions are only found if you carry two copies of a mutation - and the result is extremely serious. Something like the TCN2 gene mutation that causes severe problem in infancy. If you can type that question then you don't have that condition.

There are very, very few situations where genetic testing is going to tell you anything useful, despite the masses of mis-information on some scare-mongering websites.

I would only take a genetic test for medical reasons if I were a female who was worried about the possibility of breast cancer. The BRCA genes are reasonably good at predicting an increased risk of some breast and ovarian cancers.

I got tested with 23andMe so that I might find relatives. I've found some interesting stuff but nothing that would make me change my lifestyle.

[Wowo23]

Hi MaryBrown06. I have PA. Yes, my doc ran a gene test. I tested positive for MTHFR DNA mutation 511238. Two mutations were found. C677T and A1298C. These can not be from one chromosome so I got one from each parent. MTHFR is a key enzyme in the folate pathway.

[fbirder in reply to Wowo23]

Having mutations in the MTHFR gene has zero bearing on whether one has PA or not.

There is only one MTHFR mutation that has been shown in reputable, repeatable, studies to have any bad effects. That is being homozygous for the C677T mutation (which is carried by about 10% of the population). Even if you do carry this particular mutation most of the time it has no noticeable effect. I should know, because I am one of the 9% that has it.

Even if it did have an effect, supplementing with methylfolate would fix it. I've noticed no difference between taking methylfolate and folic acid.

Some scaremongering websites will try to persuade you that being heterozygous for both C677T and A1298C is just as bad. However, there is no good evidence for it doing anything at all.

[Gambit62 Administrator in reply to fbirder]

fbirder - MaryBrown's question was about B12 as well as PA.

Wowo23 , MTHFR is the gene that controls part of one of the key processes that B12 is used for, in conjunction with folate. The impact is not generally directly on B12 but secondary to the effect on processing of folate. Most of the genetic variants involved have very little impact on their own on processing of folate, despite, as fbirder comments, the number of sites out there pushing the importance of methylated forms of vitamins. Most of these genes also require an element of environmental factors before they start to express and I'm not convinced that the exact importance and impact of those factors is fully understood - let alone how the different variants interact with each other or even with variants on other genes.

I'm also not sure that a genetic test necessarily picks up all of the variants that could impact on processes that involve B12 and hence the metabolism of B12

I've come across dozens of genes in relation to B12 but only a very few ever get a mention on websites that say that provide information about B12.

The use of genetic profiling in medicine isn't very well advanced in the UK - there seems to be a bit more in the US - but there I'd be very wary of who I approached in relation to the testing - a lot seems to be linked to particular agendas rather than genuinely focused on improving the treatment of patients. I really have no idea what the situation is in France - have you muted the idea with your GP?

[Marybrown06 in reply to Gambit62]

Hey Gambit,

I went back to GP following our talk but she does not know anything about B12. She did not even know B12D could have neurological consequences without anemia...

I tried to ask about injections but my current level is high (850) so she says it is not necessary.

I definitely need to find a new GP.

Concerning the DNA test, I received one for Christmas and need to choose the company, I'll have a look at 23andme!

[fbirder in reply to fbirder]

Oh, I forget. 23andMe no longer include results for the MTHFR gene in their raw data from yhe latest (v5) chip.

In the past they have issued statements about how MTHFR results aren't useful. I guess that's why they've stopped reporting it.

[sue_b in reply to Wowo23]

Yes, I found out that I needed to avoid methylated vitamins altogether.

Although 23andme dont look at the MTHFR genes yu can get your genome analysed by other people. I'll PMthe ones I tried and the ones I thought were helpful.

a[ologies for the speeling errors etc, I am having keyboad issues today on this website and cannot go back and correct.

[BlueHorizonMedicals]

Hi Mary, we will have something to announce in the new year regarding this, hopefully it will be of interest.

Best wishes

Paul Harris

Blue Horizon Medicals

[sue_b]

In order for a connection between a genetic variant and a health condition to be considered real and clinically meaningful, well-run scientific studies need to show convincing and consistent evidence for that association.

I think the above is the important piece of the statement they issued. Drug companies will not pay for research into something that they can't patent. 23and me base all the info they provide on Studies that can be categorised as properly run and scientitfically based.

[fbirder in reply to sue_b]

Drug companies represent a very small proportion of publications in scientific journals. The vast majority come from universities who aren't quite as profit driven.

In the blog linked by Hidden above 23andMe state:

"Despite thousands of scientific publications, the evidence linking MTHFR to most of these health conditions is inconclusive or conflicting."

So the lack of convincing and consistent evidence isn't due to a lack of looking.