GENOTYPE TESTING

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Offline Sharmin

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GENOTYPE TESTING
« on: October 23, 2008, 09:22:58 PM »
I encourage everyone to have genotype testing done for their child - if your child is newly diagnosed it is a great time to have it done before they are transfused (or transfused too many times). 

This is the only way to protect your child from making multiple antibodies, and make the cross matching process easier.  This step can aid in preventing complications in the future.  It can also prevent transfusion reactions and antibody related hemolysis. 

Please speak with your doctors about it - there are several places in the world where this testing can be done, blood samples can be taken and sent to these locations.  Please have your blood bank inquire about where and how these samples are to be collected, stored and sent. 

Treatment is getting much better these days, please try to avoid unnecessary complications by doing this testing!!

Best of luck everyone, 

Sharmin
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Offline Manal

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Re: GENOTYPE TESTING
« Reply #1 on: October 24, 2008, 07:16:19 AM »
Sharmin, i thought genotyping is the cross match test :huh :huh

I do not know whether we do it here in my country or not. I was told that if i want to transfuse my son one day, only cross matching is required. Thanks for this post

manal

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Offline Sharmin

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Re: GENOTYPE TESTING
« Reply #2 on: October 26, 2008, 06:05:46 AM »
Manal,

From my understanding, the cross match process involves testing the recipients blood with a number of antigens and known irritants to determine which antigens the blood reacts with.  The donor blood is then tested for these antigens, and the compatible donor will, along with being a blood type match for the recipient, will not have have the antigens that the the recipient blood sample reacted with.  This is the common procedure used before blood transfusions and generally works very well. 

Children who receive multiple transfusions may over time develop sensitivity to certain antigens in foreign blood, and may begin have reactions to them or developing antibodies to antigens in foreign blood. 

Genotype testing entails testing to genetically find what antigens the recipient actually has, and also to determine the antigens which are absent.  This information is then used during the crossmatch process, thereby the donor and recipient are more closely matched on many levels.  This reduces the likelihood of reactions and antibody related hemolysis.  The recipient's body is likely to recognize the donor blood as it's own - because it is so closely matched.    This can also make finding a match much easier, because the blood bank will already know which antigens that the recipient has - therefore they do not need to be tested for in finding suitable donor blood. 

I think that this is a bit of an oversimplification - and perhaps a little incomplete - perhaps Andy can add to it. 

I believe that my son would have been much less likely to develop the antibodies he did if we had taken this step beforehand. 
I urge everyone to please find out where their child's blood sample can be sent to have these tests done.  It is possible for doctors to send blood samples to other countries.  My son's blood is being tested in Toronto for genotyping. 

Please see this thread for more information about genotype testing:

http://www.thalassemiapatientsandfriends.com/index.php?topic=1660.0;highlight=genotype+testing+sharmin

Sharmin
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Offline Manal

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Re: GENOTYPE TESTING
« Reply #3 on: October 26, 2008, 06:23:01 AM »
Sharmin,  thanks for the explaination :hugfriend

But again if these tests are not available, is it okay to have washed, filtered and irradiated blood. What do we get rid of when we irradiate blood, viruses & bacteria or antigens????????

manal

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Offline Sharmin

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Re: GENOTYPE TESTING
« Reply #4 on: October 26, 2008, 06:28:12 AM »
Manal,

Washed blood cells reduce some of the exposure, but you can still have reactions.  Also, red cells can be damaged during the process by which they are washed so the blood does not last as long - and you are still getting the same amount of iron.

I don't think that there is a substitute for finding a compatible donor - and genotype matching is the best method.  I can try to find out where you can have this testing so you can arrange to have this done now - just in case - even if you never need it. 

Sharmin
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Offline Sharmin

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GENOTYPE TESTING - please have it done!!
« Reply #5 on: January 21, 2009, 04:55:03 PM »
Dear thalpals,

In recent months I have been in touch with at least 5 thalassemia patients who have developed auto antibodies.  Auto antibodies can cause rapid hemolysis and increase transfusion requirement and cause iron overload.  Some of the patients I have spoken to have had devastating consequences due to antibodies.  A few of the patients are transfusing twice a week to keep up with the hemolysis.  It is very difficult to maintain lower iron levels even with intense chelation when the transfusion requirement is so high.  Our family went through a difficult time with my son's antibodies, luckily for us his antibodies were not as severe as they can be for others.  Several families have suffered a great deal from antibodies and it is heartbreaking to watch them suffer. 

I encourage everyone to please get more information about genotype testing in order to avoid this devastating complication to an otherwise manageable disease.  If anyone has questions you are very welcome to ask me.  I think that many people think that the test is too sophisticated or believe that the center they are being treated at cannot do it - and therefore they end up not pursuing it.  Please know that it is very possible to have a blood sample sent to another lab to have this test done.  If your doctors don't understand then you can bring information to them about it, but this is something that is worth pushing for. 

Sharmin
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Offline Zaini

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Re: GENOTYPE TESTING
« Reply #6 on: January 21, 2009, 05:48:55 PM »
Sharmin,

I've tried checking for it,but it seems like no one gets me,and the truth is that although you have explained it quite a few times but i am unable to understand it properly  :imsorry dumb me , still i tried to explain it to people in blood bank and lab that it is done to match donor blood better so that patient won't develop antibodies in future ( am i making any sense ??? ) but they keep asking me what kind of genotyping,they said they do hcv genotyping ??? something meant to diagnose hepatitis, so i really don't know what should i do,the lab we go to is one of the most advanced labs in country so.... i'll talk again to her doctor.

One more thing,is there any use of genotyping after several years of transfusing,i mean the body is exposed to foreign elements anyway?

Zaini.
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Offline Zaini

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Re: GENOTYPE TESTING
« Reply #7 on: January 21, 2009, 05:50:59 PM »
On second thoughts,

I think i should print this page and ask her doctor to read it.

Zaini.
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Offline Sharmin

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Re: GENOTYPE TESTING
« Reply #8 on: January 21, 2009, 06:02:38 PM »
Hi Zaini,

I am glad that you asked.  Many doctors don't even understand what genotype testing is so it is very difficult for us parents to understand it.  
I will post and also send you something that describes the test properly.  

Little A just had his genotype testing done this October so it is okay to do after being transfused.  In genotype testing they look at the DNA.  
Our kids are transfused red blood cells - RBCs don't have a nucleus or DNA.  For dna testing when the blood is drawn, they test the nucleated cells in the blood (which is the patient's own dna) and they determine what is genetically the best type of blood to give to the patient.  

I think what is confusing you is that in the past we have also talked about phenotype testing - phenotype testing requires red blood cells - and this test needs to be done before any transfusions take place because transfused patients don't make very many rbcs - and they often have a lot of transfused rbcs and the test results would be inconclusive.  

Genotype testing can be done at anytime.  I think that some people are more prone to producing antibodies then others - my son is being transfused in a country where most of the donors are white - therefore he was more likely to produce antibodies.  However, in recent months I have heard of 3 patients who have produced auto-antibodies in India and the consequences have been devastating.  

I will try to post the information that your lab will require and the address to which they can send the sample very soon.  

Sharmin
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Offline Sharmin

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Re: GENOTYPE TESTING
« Reply #9 on: January 21, 2009, 06:10:51 PM »
Zaini,

This information that Andy posted last year may be helpful to you as well:

Quote
I've been reading about blood matching which has been done using phenotyping. In recent years, it has been shown that genotype matching of blood can give a more accurate match.

http://www3.interscience.wiley.com/journal/98518982/abstract?CRETRY=1&SRETRY=0

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Genotyping was very important in determining the true blood groups of many polytransfused patients with -thalassemia, and it assisted in the identification of suspected alloantibodies and the selection of antigen-negative RBCs for transfusion.

By using this along with phenotyping, a better match is found. After many transfusions, it becomes difficult to determine the true blood type because so many foreign antibodies have been introduced via transfusions. Genotyping matches for the true blood type.

http://cat.inist.fr/?aModele=afficheN&cpsidt=1466407

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After multiple transfusions, the serologic typing of autologous blood group phenotypes is difficult, because of mixed RBC populations. The genotyping of ABO, Rh, Kell, Kidd, and Duffy systems could be used to determine autologous blood group antigen status...Genotyping from peripheral blood produced results identical to the autologous blood group phenotypes, regardless of the amount of blood transfused or of the length of the sampling period after transfusion. CONCLUSION: A fast and reliable PCR.sequence-specific primer DNA genotyping assay for simultaneous determination of autologous ABO, Rh, Kell, Kidd, and Duffy blood groups can be performed on peripheral blood samples, even though the patients have recently received multiple transfusions.

http://cat.inist.fr/?aModele=afficheN&cpsidt=18300371

Quote
The development of red blood cell (RBC) isoimmunization with alloantibodies and autoantibodies complicate transfusion therapy in multiply transfused thalassemia patients...In conclusion, the transfusion of matched blood is essential for chronically multiply transfused patients in order to avoid alloimmunization. Considering the high frequency of anti E at our hospital, it is advisable to genotype patients and match the red cells for E antigens in multiply transfused thalassemia patients.


I do not know where the current state of genotyping is or if it is even being done on a routine basis. There is a movement in Europe to replace the old method of phenotype with DNA genotype. There is a group called Bloodgen that is working to make genotyping the standard for blood matching.

http://science.uwe.ac.uk/projectshowcase/neil_avent.asp

Quote
Bloodgen is an international consortium led by Professor Neil Avent and colleagues in FAS. The consortium aims to use genotyping to improve patient safety and blood transfusion compatibility.

In most developed countries safe blood transfusion is taken for granted. But, not all blood groups are compatible, and blood grouping is complex, with two cross-matching tests required prior to transfusion.

What's more, these tests are based on technology that has not changed since the early days of blood transfusions. Bloodgen aims to change all that with the development of a 'Bloodchip' - a CE-marked commercial product that will be sold to Blood Services worldwide.

There are 29 different blood group systems but currently only ABO and Rh (Rhesus) are routinely tested for. Professor Avent, Director of UWE's Centre for Research in Biomedicine and leader of the project said:

"Inevitably there is going to be some incompatability with blood transfusions, especially in those that receive multiple transfusions, because if it is incompatible the patients' immune system will create an antibody. Blood grouping at the moment uses antibodies that interact with proteins on the surface of cells.Our research looks at blood group specific genes which vary from one individual to another. This is certainly a safer means of testing blood because of its comprehensiveness. The Bloodchip will embrace all blood groups that are clinically significant and we'll be able to have those tested on a routine basis."

"The ultimate goal is that a new technology will come in and replace techniques that have been around for 100 years or so. Genotyping is incredibly accurate and could be used for a wide range of routine testing of patients in the near future."

The Bloodgen consortium, which is supported by a large EC Framework V grant, pulls together expertise from around the globe. The partners are: Biotest AG Dreieich, Germany; Bloodbank, Rotterdam; Blood Group Reference Centre, Barcelona; Institute of Haematology and Blood Transfusion, Prague; the North Bristol NHS Trust, Southmead, Bristol; Progenika SA, Spain; Sanquin Research Foundation, Amsterdam; University Hospital, Lund; University of Ulm, and the University of the West of England, Bristol (lead partner).

Genotyping will eventually replace phenotype matching of blood. One article I read from 1999 talked about the white population having been genotyped but others, such as Asian still needed to be done. I don't know how much progress has been made in the past nine years but I think this is an important subject to bring up when you speak with Dr Vichinsky.

I read until I couldn't keep my eyes open the past two nights, trying to find information for you and Rozitka about antibody reactions. It is somewhat frustrating because it is a very difficult problem that affects a percentage of those receiving blood transfusions and there are no easy answers. I hope each little bit of knowledge can come together to help in some way.

I will try to get more info ASAP,

Sharmin
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Offline Zaini

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Re: GENOTYPE TESTING
« Reply #10 on: January 22, 2009, 02:53:34 AM »
Thanks Sharmin for the info,

I am going to visit her hemo when she finishes her first box of Asunra,i am going to ask her to look into it,i will print these pages and give them to her.

Zaini.
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Offline Sharmin

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Re: GENOTYPE TESTING
« Reply #11 on: January 24, 2009, 09:44:18 PM »
Zaini,

In order to avoid confusion - you can try to mention to your doctor that in thalassemia dna (genetic testing) is done for three reasons. 

First is for diagnosis - learning the mutations that are causing the anemia. 
Second is for HLA matching - (histological) tissue matching for transplant
Third is to determine the patient's genetic make up for red blood cells - so that the agglutinogens on the surface of the donor red blood cells match the agglutinogens on the surface of the recipient's blood cells. 

The following articles provide more information about genotype testing:

http://www.haematologica.org/cgi/content/full/93/9/1408

http://www.nationalreviewofmedicine.com/issue/2008/01_15/5_advances_medicine_1.html

I hope that this helps.

Sharmin
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Offline Zaini

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Re: GENOTYPE TESTING
« Reply #12 on: January 25, 2009, 07:58:15 AM »
Thanks Sharmin,

I sure will.

Zaini.
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Offline Dori

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Re: GENOTYPE TESTING
« Reply #13 on: January 25, 2009, 11:50:51 AM »
My hospital do not have a lot of tests, but they do genetesting by transfusion. Do you always give 72hours before transfusion the blood for the match? (is there a better word for in EN?). I still can remember that I went for a transfusion in the local hospital (5min from home by bike). I let them took the blood at 8am and transfusion started at 9am.

Sharmin, will the antibody disappear? How long takes such treatment? Does he take prednison? I am so sorry, but I have no idea how they treat it.

 :hugfriend

 

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