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Author Topic: R242H Mutation in MYH Gene?  (Read 272 times)
riders4
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Frank Rider


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« on: May 30, 2009, 08:33:31 AM »
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I was informed of my MYH gene sequencing test results yesterday.  My initial PCR test had identified one copy of the G382D mutation, and because of my polyposis a second copy was suspected.  The sequencing test result indicated I have two different mutations - the G382D as well as an R242H mutation.  I've never heard of the R242H mutation before.
I have put my "googling" skills to work but am unable to find information about the R242H mutation of the MYH (or MutYH) gene.  My knowledge in this area is, of course, very limited.  I did find information on-line about an R242H mutation in a different gene (SDHB), but I suspect that has nothing at all to do with my test results or condition. Can anyone point me to information about this lesser-known mutation of the MYH gene?
In particular I would like to learn what is known about:
1. likelihood of passing these mutations on to my offspring, and
2. any known or suspected "extra-colonic" complications associated with these mutations.
(I expect to have the opportunity to learn more about these results in about a week when I can talk with the genetic oncologist at UNC who ordered the sequencing test in the first place.  I am already scheduled for protocolectomy and IPA (J-Pouch) surgery this coming September.

~~ Frank ~~
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51 y.o. husband and dad; MYH-associated polyposis (two mutations), proctocolectomy, IPAA and J-Pouch surgery 09-10-09.  Have recovered very well, adjusting to changes.
Charlotte
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« Reply #1 on: August 11, 2009, 05:25:29 PM »
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Hi Frank - Did you ever learn any more about the R242H gene? I would be interested to hear about it! Do you have a date for your surgery? Hope all is well - Charlotte.
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MYH Associated Polyposis
Subtotal Colectomy 4/21/09 (Ileum to Sigmoid Resection)
Hoping to Prevent Cancer
Sara R
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« Reply #2 on: August 12, 2009, 08:37:57 AM »
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I may have answered this in private, but wanted to give you an update Frank.

I didn't find anything when I did a PubMed search for R242H.

When I was at a genetic testing lab  this summer for an internship (I won't mention any names, but they do a ton of genetic testing *wink wink*), I thought of you Frank and asked about the MYH mutations. I didn't remember your specific one but asked in general.

The information I received from the counselors at the lab was that MYH testing is so new (relatively) that they just don't have enough information about the different mutations (like your R242H). Sometimes many people have a gene change (like G382D), but then maybe a handful of people may also have R242H. There is also a chance that you might be the only one with R242H. In genereal, MAP is associated with an attenuated FAP phenotype.

What you can do, is call who ever ordered the genetic testing, and ask them to call the lab that did the testing to see how many other families have the same G382D/R242H gene changes. You could call the lab yourself, but they are more likely to give this detailed information to a trained medical ear of a doctor or genetic counselor.

When a person has MYH-Associated Polyposis, it is inherited differently that classical FAP. It required a change of both copies of the DNA in order to present symptoms. So therefore both copies of your MYH gene have a change on them that causes them to not work properly.

You will have a 50% chance to pass the G382D and a 50% chance to pass the R242H gene to each of your kids... they will get one or the other. This means they will all be carriers for MAP. If your wife were a carrier, then there would be an increased chance for them to have MAP, like you. I believe that about 1 in 100 people are carriers for MYH. 

If your wife is a carrier, then there would be a 50% chance for each child to have MAP.

Your wife and/or your children can also have genetic testing to determine their chances for being non-affected carriers or having two gene changes that cause MAP.

-Sara


There is an article that discusses genotype-phenotype correlations:
APC, MYH, and the correlation genotype-phenotype in colorectal polyposis.
Ann Surg Oncol. 2009 Apr;16(4):871-7. Epub 2009 Jan 24.

It's listed in this forum.
« Last Edit: August 12, 2009, 08:39:40 AM by Sara R » Logged

FAP diagnosed in 1994 (age 10) based on family history & cysts
Colectomy & Brooke Ileostomy in 2002
IPAA-Jpouch in 2005
Desmoid tumors detected in 2005

Graduation from USC GC program in 2010.

"Life is all about catching the unfair side to a fair coin." -Dr.
Charlotte
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« Reply #3 on: August 12, 2009, 06:16:30 PM »
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Thank you, Sara for this info. Good luck with your continued studies towards becoming a genetic counselor. I find genetics very interesting. Since all this colon stuff has come up in my life, I would love to pursue something in health sciences relating to colon cancer, but I have already completed my education (law) and still many years of paying off student loans to go. Maybe one day if I win the lottery I can go back to school full time! Wishing you well!  Smiley
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MYH Associated Polyposis
Subtotal Colectomy 4/21/09 (Ileum to Sigmoid Resection)
Hoping to Prevent Cancer
riders4
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Frank Rider


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« Reply #4 on: August 15, 2009, 04:24:06 PM »
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Hi Ladies,

First, Charlotte, yes, I am scheduled for surgery September 10.  I have to have a proctocolectomy (IPAA) and J-Pouch to, like Charlotte, prevent cancer; and the chances are strong I can have everything done in a single surgery.  7-10 days for recovery in the hospital, I'm told - maybe a day off for chewing lots of gum after I wake up  Wink

Second, Sara, thanks so much for thinking of me while you had an opportunity to do some learning during your summer internship.  I think it's great you are able to pursue professional opportunities related to something so unfair that popped into your life.  I am reminded of the saying, "When you get a lot of lemons, make lemonade." 

I've been trying to make lemonade, too.  Most significantly, my wife and I just got back Thursday from a great Second Honeymoon trip, a week on Maui.  We've been married for 12 years, and when it became clear I would need this surgery, but unclear how it might effect me in the longer term, I was determined to at least schedule things so we could enjoy a full summer of good health and do some things we would not have to regret later having missed.

In addition, I am seeing my surgery and hospitalization as the best chance I'll ever have to quit smoking cigarettes; and as someone who is always a hard worker, at home and professionally, I have also framed my upcoming recovery period as a time of much needed, well-deserved rest for myself.
(I've been stocking up on movies, reading and music to help pass the time between laying down and becoming best friends with my bathroom.  (Maybe I should build some bookshelves and set up a little home office next to the toilet?)

What we have learned about my MYH mutations through Emory's lab and my UNC genetics team is about the same as what you've shared here, Sara.  It is nearly a certainty one of my mutations is on each copy of the gene, but we had blood drawn from my 8 y.o. son in late July to test for any MYH mutation in his genes; that, in turn, will most likely find him to be a carrier and therefore confirm that my mutations are not on the same side as one another - a very slim possibility that, according to the UNC folks, could send us back looking for a previously undetected APC mutation.  [I hope to gawd not, because that would put us back to the possibility of my kids having a 50-50% chance of inheriting the polyposis disease, instead of the much more remote (1 in about 200) chance of inheriting the condition via MYH recessive transmission.]  Selfishly, it will be hard enough dealing with my own changes, I would do anything to eliminate the chance of having to worry about passing the same stuff down to my kids!

Like you said, Sara, the learning in the field about MYH is still very new and incomplete.  The folks at UNC actually used my test results in June as the focus of a class session, as they had not previously encountered my combination of these mutations.  That process helped them realize the sequencing tests at Emory could not definitively tell them whether my mutations are on both sides, versus on a single side, of the MYH gene; so the testing for my son was seen as the next logical step.  (We have not had my wife tested for carrier status at this point, but like you, I understand that to be about a 1-2% incidence.)  My wife and I wonder if this all makes sense to you, Sara?

Now that we have enjoyed our wonderful trip to Maui we are beginning to let some more reality set in, and begin to prepare for things.  I am actually very proud of myself for not having let this whole business get me down in a funk and squader away these healthy months for me and my family.  I still have scheduled a couple more business trips between now and my surgery date, in part to keep my mind full of productive considerations; and if I want to allow myself to get bummed out - even in light of this great opportunity to avoid virtually certain CRC - then I can at least compress all that into the timeframe around and after the surgery itself, right?

Thanks for the tip on the January journal article - not sure whether I've already read it, but I'll check it out after I sign off here.  Meanwhile, my sense from the professional literature is that the field is really moving forward, we may be within striking distance of a new level of understanding that can lend itself to earlier detection, less invasive prevention strategies than surgery, and an overall greater success rate in finding and defeating genetically-caused cancers.  It is an exciting time to be entering this field of genetic oncology, Sara - good for you!

Ongoing best wishes to everyone here,

~~ Frank in NC ~~
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51 y.o. husband and dad; MYH-associated polyposis (two mutations), proctocolectomy, IPAA and J-Pouch surgery 09-10-09.  Have recovered very well, adjusting to changes.
Sara R
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Future Genetic Counselor


« Reply #5 on: August 19, 2009, 05:16:54 PM »
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Congratulations on your second honeymoon! I'm glad to hear that you were able to enjoy your vacation in Maui. It's always nice to have a real vacation before surgery. I hope you were able to relax Smiley

To get to your question, if they tested your son and did full-sequencing of MYH and he only has one change, then he is a carrier. It wouldn't matter if they tested your wife because her results wouldn't change your son's results. For example, if your wife is a carrier then the next thing is to test your son... and that testing has already been done.

Testing your wife would be more for a peace of mind, or if you were considering having more children in the future it could maybe determine their risk... but testing may not be cheap, and I'm not sure how common it is for them to reflex to full-sequencing for a non-affected person if one of the more common gene changes isn't found first.

From what you've told me it sounds like the lab and clinicians have done a thorough work-up of testing. I think the next best step for you right now is to relax and get ready for your upcoming surgery Smiley

I remember drinking lots of water, gatorade, V8 Splash, and chocolate Ensure...

Good luck with your upcoming operation! I hope you have a speedy recovery. Keep us posted with your progress.

-Sara
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FAP diagnosed in 1994 (age 10) based on family history & cysts
Colectomy & Brooke Ileostomy in 2002
IPAA-Jpouch in 2005
Desmoid tumors detected in 2005

Graduation from USC GC program in 2010.

"Life is all about catching the unfair side to a fair coin." -Dr.
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