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Genetic Mapping - anyone experienced it?

31 replies

waterbaby · 23/09/2003 16:21

Hi all, we have a history of a lot of cancer in my extended family, going back through all of the generations in living memory. One of my cousins recently lost her mum, and in working through her grief has decided to 'do something' about it.

The two aunts who have battled cancer and survived have agreed to go for some blood tests and their blood will be checked for genetic abnormalities. The idea is that, although the technology migt not be here now, this might offer DD's generation a fighting chance.

I want to support my cousin as much as possible and the possibilities are quite exciting... but also daunting. Has anyone been through this? I can imagine it might be a rollercoaster!

OP posts:
waterbaby · 26/09/2003 12:09

Anybody got any ideas? Would you want to know you were at a higher risk for x,y, or z if you were me?

OP posts:
SoupDragon · 26/09/2003 12:17

Hmmm... I don't know TBH! Part of me thinks yes, that's it;s best to know so you can look for early symptoms. You already know you're at a higher risk because of your family history so I guess you wouldn't be finding out much you don't know already... would you?

The other part of me would want to bury my head in the sand and ignore it.

Sorry... not much help really but wanted to post something!

tamum · 26/09/2003 13:01

Without wanting to sound at all as though I'm trivialising your problem, I would say that SoupDragon is quite right, the issue here is one of early detection and intervention. Testing for something like Huntington's is really complex and personal because at the moment there is NO treatment and nothing to be done, so finding out you have the mutant gene is a truly negative experience. Cancer, for all its horror, is different. If you know you have a particular mutation then you can get regular screens of the relevant type. That way you really are maximising your chances of being cured.

I really understand your reluctance, but I would say it is a good thing if you can bring yourself to do it, always assuming that they can find anything. I lecture in genetics, so if you want to ask anything on or off mumsnet I'd be happy to try and help.

zebra · 26/09/2003 13:07

I strongly suspect that something like 99% of us are at genetic risk for some awful condition or another. But "risk" is relative; actually, the highest risks of all are lifestyle factors (ie., smoking, sedentary lifestyle, poor diet...). Handy, because you can do an awful lot to change your lifestyle, but you can't change your genes (not yet, anyway). Then there are environmental risk factors (like pollutants in the air we breathe or food we eat), and we usually have some influence over those, too. You can choose to have fewer soft furnishings in your house, for instance, and then you'll have lower indoor air pollution.

So I might get my gene profile done if it were cheap and easy, out of curiousity, but I wouldn't "believe" in it, very much.

That said, if I were you, Waterbaby, I'd give a blood sample to see if they could find a vulnerability in your family. That way you'll be giving your DD's generation more information when they make their own health choices.

waterbaby · 26/09/2003 13:32

Thanks everyone - we're going for it as my cousin is so definate and as her closest friend I would do anything to help her through this grief. But because its not something we have researched and considered from every angle ourselves I wanted to see if anyone else had, and particularly if they had done it on a large scale like this - whats going to happen to the family dynamics etc, as Tamum points out, this is quite personal but relevent to us all at the same time.

Until now we have been sticking our head in the sand a bit soupdragon, and at least, as Zebra and Tamum point out too, there are some things that we can do about certain risks... there are others that the doctors have already explained may turn up but not be treatable. I guess thats the scary bit, and we'll deal with that when we come to it. Because so many of us are giving samples, we don't actually have to say now if we want to know the results, IYKWIM. They have said that they might find something, nothing, or something but not for a long time. But my family are a load of blubbermouths so we are all bound to find out about each others... and wondering about our own would be worse than knowing in some ways.

Tamum, I'll be in touch as we get more information, at the moment I don't have many specifics to ask questions about, but thanks - the offer is very kind!

OP posts:
zebra · 26/09/2003 13:43

Let us know what happens, Tamum?

I can imagine a "worst" case scenario -- you find out that you & your DD are clear, but your cousin and her children have "rogue" cancer-causing genes. Your cousin feels devastated that she might die young like her mother. Jealous of you or anyone that doesn't have this burden. You feel guilty for being "safe". [Then you get hit by a bus the next day...!]

No -- Then she asks what it means in case of increased risk, and the answer might will be "We don't know". But if the docs did know... What if the true risk increase is only something like 3% provided she doesn't smoke & gets some exercise. Would 3% increase in risk really worth worrying about? Problem is, you don't know how your cousin will deal with it; 3% is still too much for some people. What if it's 30% increase in risk; unpleasantly high, but still not a total certainty, is it? Maybe the lack of certainty in the results is what you truly have to prepare yourself for.

zebra · 26/09/2003 13:44

OOps, I meant to address that to Waterbaby, not Tamum!

waterbaby · 26/09/2003 14:15

Good advice Zebra, I'll make sure we talk about that when we see them - and don't worry, we will keep looking both ways when we cross the road!

Planning a long and health life thasnksd very much! Can you tell me a bit more about the indoor air pollution from the soft furnishings? We're careful about what we eat / put on our skin in the way of cosmetics and soaps etc, and are going towards wooden flooring and away from carpets...

OP posts:
tamum · 26/09/2003 15:05

Zebra makes some good points; the thing is it depends on what they're looking for. The only way there could be a scenario like a 3% increase in risk would be if they were going to sequence all of your family's genomes, and they're not; it's just not financially or technically feasible at the moment. What they will be doing is to look for mutations in genes such as those that code for proteins involved in DNA repair. If they find something like that then it will be fairly cut-and-dried in terms of risk assessment.
But, zebra is right- the possible scenarios have to be thought through. I would very much hope that they will offer you all a fair bit of counselling before they embark on anything major. Good luck, to you and your cousin!

JJ · 26/09/2003 18:53

Waterbaby, what kind of cancer? My family has a history of colon cancer to the point of where I know I'll get it. My goal is to not have to have radio- or chemo-therapy and get the cancer simply cut out like my mom did (and not need the aftermath). Obviously, people don't actually have a choice and what I'm trying to say is that I'm seriously aggressive in detecting it. And not to say that it's easy as early detection.

Anyway, what cancer is it? Why do you need genetic counselling? (Just curious, really, as someone who could benefit from the info.. My dad's mum died from "stomach cancer"; dunno exactly what that was as she died when he was young.)

hmb · 26/09/2003 18:57

And just as a follow up, is there a lot of a specific cancer in your family, colon or breast or whatever. Or is there a lot of different kinds of cancer? Because not all cancers are the same. If it is a mix of them there may not be a predisposition due to genetics, it might just be bad luck

tamum · 26/09/2003 19:17

JJ, for what it's worth, you can't be sure you'll get it. In some families colon cancer is certainly caused by a single gene defect, but at worst you've got a 50:50 chance of having inherited it unless there's a lot of first-cousin marriages or something (don't mean to be rude, just being a geneticist ). Have you not had counselling? I'm absolutely certain you'd be entitled to it if you wanted it, from what you've said, and there are direct genetic tests for most familial colon cancers that might put your mind at rest.

tamum · 26/09/2003 19:20

The thing is, hmb, there are quite a few genetic defects that predispose to all sorts of different cancers. You're absolutely right of course, it could be a coincidence, but I was assuming that if anyone's willing to start a linkage study they'd be pretty sure about the family history appearing to be genetic.

JJ · 26/09/2003 20:01

Tamum, yes. I might not get colon cancer.

But I'm willing to bet you good money here....

Um. what's the syndrome with all the polyps? There's something there, right?

Sorry for being so contrary. My grandfather died with this (the colon cancer thing) and my mother didn't. Just wondering how genetic testing is going to help me and why anyone thinks I'm not getting colon cancer.

I'm so against genetic testing in relation to insurance. Not that it was a topic. But, y'know, all the same words.

tamum · 26/09/2003 20:09

Oh yes, me too (insurance I mean).

Hereditary polyposis coli, familial polyposis of the colon, several different names. The reason you are just as likely not to get it as get it is that it's nearly always dominant. That means if you get one copy of the mutant gene you get the disease. Anyone with the mutation does however have a normal copy too (everyone has two copies of each gene apart from some X linked genes in men). This means, since your mother had the disease, that she had one good and one bad copy of the gene (sorry if that sounds patronising, just easier to type ). You will only have inherited one copy from her (and one from your dad), and so you have just as high a chance of having her good copy as having her mutant copy. Therefore there's a 50:50 chance that you would get reassuring news.

Phew! Sorry to be so wordy

JJ · 26/09/2003 20:57

Not patronising at all, just more justification to get tested? 50 :50 are pretty even odds.

Must not die. Must not die.

As I tell my doctors, I really don't to be diagnosed late.

I'm very aggressive about this so not actually that worried.. I don't think it hurts.

My doctors are great, although I don't like the idea of things (ie non-sexual things) being shoved up my butt.

Or the idea of genetic testing? I don't like that either.

WideWebWitch · 26/09/2003 21:04

Waterbaby, just wanted to say good luck with this - some interesting points made here about counselling and what you can do about it etc if news isn't great. JJ, I hope the news is reassuring if you are able to get any sort of definitive test.

JJ · 26/09/2003 21:28

Oh dear, please don't be worried. I'm wholly and fully prepared on getting cancer. It's colon cancer; catch it early, umm, catch it .. um... don't know. But been there done that. (Well, not me, that's how I got my feet wet with the medical profession as it were. Ie, that's how I became the total and utter bitch. And they were nice.)

Oooh, I'm devolving into sister mode.

huh huh, huh huh

WWW, you're so sweet.

WideWebWitch · 26/09/2003 21:36


tamum · 26/09/2003 21:48

Small comfort maybe JJ, but the actual genetic testing need not involve butts at all. I'm sure the doctors would prefer to have a quick shufty, but the genetics could all be done with a small blood sample. Let me know if I can help at all (not with the butt bit, obviously )

JJ · 26/09/2003 22:14

Tamum, thanks. No, as someone who will (ok maybe not) get colon cancer, I'm resigned to the getting the thing shoved up your butt mode of detection. Not to say I don't love blood and what it can tell you. I just think it lies.. hardee har har... bwahh haa ha.

(Um, just to reiterate, it's Friday night.)

No, anyway, genetic testing? That's betting on ones genes, right?

(oh, yeah, there are very good arguments to be had there... )

robinw · 27/09/2003 07:36

message withdrawn

JJ · 27/09/2003 10:16

So.... can I change my mind and ask you to explain what I'd know if I had it done? What would it tell me?

Thanks. I'm, perhaps obviously, a little bit freaked out by the idea.

tamum · 27/09/2003 10:45

Hi JJ,

Yes, I can completely understand why it's a bit freaky. I have to stress that you'd be better off getting genetic counselling because I'm not a medic, and don't know anything about the clinical features of the colon cancer in your family, but I'll certainly help as much as I can. Did your mother and grandfather have polyps too? There's a genetically separate group of colon cancers called (imaginatively) hereditary non-polyposis coli where polyps aren't a feature, but the genes involved in this category have been identified too. Basically, if you have one of the types of colon cancer in your family for which the gene has been identified (which is most of them), you would then take a blood test. They would extract DNA from your blood, sequence the genes concerned, and then tell you whether you have the mutant form, in which case you are at greatly increased risk of developing colon cancer, or the normal form, in which case you're at no more risk than anyone else.

BUT- I don't know all the ins and outs of your family pedigree, so you need to take anything I say with a pinch of salt. It's also possible that it's a complete coincidence that your mother and grandfather both had the disease; it's sufficiently common in the normal population for that to happen. Feel free to email me if you want to talk about it off mumsnet.

JJ · 27/09/2003 16:51

Thanks tamum, I've just sent you an email. It's the polyp-y kind and all my aunts and my mom have them (4 women altogether). My mom is the only one who has had cancer so far.

Does anyone know the insurance consequences of genetic testing? If I get this done and it's positive (ie I have the gene) will it hurt me the next time I go to get insurance?

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