Anyone had negative gene test?????

[Catiesmom]

Hi all~
I posted a few days ago that my 4-month old had been presumptively diagnosed with CF and is being treated with enzymes, breathing treatments, CPT, etc.

Her doctor called this morning and said the gene study was negative. This is the one that tests for 90% of the CF genes. He said that does not mean she does not have CF, and that he is sending out for an expanded gene panel.

He also wants us to go to the CF clinic in Ft. Worth this week for sweat testing. I understand sweat testing is more accurate.

I'm just wondering if any of you have had negative gene tests, but positive sweat tests? I feel so confident she does not have this, but I don't want to kid myself about things either.

And again, if she doesn't have it, what is wrong? Why all the nasal mucus and the low weight gain? I'm pretty certain it is not Celiac.

Thanks!

 

[Catiesmom]

Hi all~
I posted a few days ago that my 4-month old had been presumptively diagnosed with CF and is being treated with enzymes, breathing treatments, CPT, etc.

Her doctor called this morning and said the gene study was negative. This is the one that tests for 90% of the CF genes. He said that does not mean she does not have CF, and that he is sending out for an expanded gene panel.

He also wants us to go to the CF clinic in Ft. Worth this week for sweat testing. I understand sweat testing is more accurate.

I'm just wondering if any of you have had negative gene tests, but positive sweat tests? I feel so confident she does not have this, but I don't want to kid myself about things either.

And again, if she doesn't have it, what is wrong? Why all the nasal mucus and the low weight gain? I'm pretty certain it is not Celiac.

Thanks!

 

[Catiesmom]

Hi all~
I posted a few days ago that my 4-month old had been presumptively diagnosed with CF and is being treated with enzymes, breathing treatments, CPT, etc.

Her doctor called this morning and said the gene study was negative. This is the one that tests for 90% of the CF genes. He said that does not mean she does not have CF, and that he is sending out for an expanded gene panel.

He also wants us to go to the CF clinic in Ft. Worth this week for sweat testing. I understand sweat testing is more accurate.

I'm just wondering if any of you have had negative gene tests, but positive sweat tests? I feel so confident she does not have this, but I don't want to kid myself about things either.

And again, if she doesn't have it, what is wrong? Why all the nasal mucus and the low weight gain? I'm pretty certain it is not Celiac.

Thanks!

 

[JazzysMom]

The problem with genetic testing is that there is always the possibility the patient has an unknown mutation. They have discovered tons of mutations over the years and there are different "variables" with the mutations that can cause some validity in them I have discovered. After reading Ambry Genetics website it gave me a better understanding of WHY using them for genetic testing is so important. Its not just how many mutations they test for, but they also "play" with the "variables" in the genetic arena that makes a difference. Its kind of hard to explain, but if you have time read this link: <a target=_blank class=ftalternatingbarlinklarge href="http://www.ambrygen.com/ts/ts_cf.htm
">http://www.ambrygen.com/ts/ts_cf.htm
</a>
Maybe this will help explain how genetic testing for CF works a bit better.

A sweat test showing negative has happened with people showing gene mutations after genetic testing (see Allysa's blog). I think that is why both are often used. And vice versa tho I cant remember off hand who has dealt with that. IF its not CF and not Celiac, maybe another pancreatic issue. I suggest keep treating as CF until you have completely exhausted all CF testing. Keep the ?? coming!

 

[JazzysMom]

The problem with genetic testing is that there is always the possibility the patient has an unknown mutation. They have discovered tons of mutations over the years and there are different "variables" with the mutations that can cause some validity in them I have discovered. After reading Ambry Genetics website it gave me a better understanding of WHY using them for genetic testing is so important. Its not just how many mutations they test for, but they also "play" with the "variables" in the genetic arena that makes a difference. Its kind of hard to explain, but if you have time read this link: <a target=_blank class=ftalternatingbarlinklarge href="http://www.ambrygen.com/ts/ts_cf.htm
">http://www.ambrygen.com/ts/ts_cf.htm
</a>
Maybe this will help explain how genetic testing for CF works a bit better.

A sweat test showing negative has happened with people showing gene mutations after genetic testing (see Allysa's blog). I think that is why both are often used. And vice versa tho I cant remember off hand who has dealt with that. IF its not CF and not Celiac, maybe another pancreatic issue. I suggest keep treating as CF until you have completely exhausted all CF testing. Keep the ?? coming!

 

[JazzysMom]

The problem with genetic testing is that there is always the possibility the patient has an unknown mutation. They have discovered tons of mutations over the years and there are different "variables" with the mutations that can cause some validity in them I have discovered. After reading Ambry Genetics website it gave me a better understanding of WHY using them for genetic testing is so important. Its not just how many mutations they test for, but they also "play" with the "variables" in the genetic arena that makes a difference. Its kind of hard to explain, but if you have time read this link: <a target=_blank class=ftalternatingbarlinklarge href="http://www.ambrygen.com/ts/ts_cf.htm
">http://www.ambrygen.com/ts/ts_cf.htm
</a>
Maybe this will help explain how genetic testing for CF works a bit better.

A sweat test showing negative has happened with people showing gene mutations after genetic testing (see Allysa's blog). I think that is why both are often used. And vice versa tho I cant remember off hand who has dealt with that. IF its not CF and not Celiac, maybe another pancreatic issue. I suggest keep treating as CF until you have completely exhausted all CF testing. Keep the ?? coming!

 

[NoExcuses]

<div class="FTQUOTE"><begin quote><i>Originally posted by: <b>Catiesmom</b></i>
I understand sweat testing is more accurate.

</end quote></div>


Sweat testing is absolutely <b> not </b> more accurate!!!!! It's a much older, more variable test than genetic testing. There are many people on this board who can share with you their false positives or false negatives with sweat testing.

Genetic testing should test for all known CF genes. I don't know the point of testing for 90% of genes... seems like a pointless exercise. Genetic testing is much less inaccurate than genetic testing.

Good luck.

 

[NoExcuses]

<div class="FTQUOTE"><begin quote><i>Originally posted by: <b>Catiesmom</b></i>
I understand sweat testing is more accurate.

</end quote></div>


Sweat testing is absolutely <b> not </b> more accurate!!!!! It's a much older, more variable test than genetic testing. There are many people on this board who can share with you their false positives or false negatives with sweat testing.

Genetic testing should test for all known CF genes. I don't know the point of testing for 90% of genes... seems like a pointless exercise. Genetic testing is much less inaccurate than genetic testing.

Good luck.

 

[NoExcuses]

<div class="FTQUOTE"><begin quote><i>Originally posted by: <b>Catiesmom</b></i>
I understand sweat testing is more accurate.

</end quote></div>


Sweat testing is absolutely <b> not </b> more accurate!!!!! It's a much older, more variable test than genetic testing. There are many people on this board who can share with you their false positives or false negatives with sweat testing.

Genetic testing should test for all known CF genes. I don't know the point of testing for 90% of genes... seems like a pointless exercise. Genetic testing is much less inaccurate than genetic testing.

Good luck.

 

[JustDucky]

Yes, this has happened to me...I was tested initially with the less extensive panel. Ultimately I was tested with the extended Ambry panel and came up with very rare deletions, less than 1% of the CF population have them. My sweat tests are in the borderline range, 49 and 50 but my ratios were consistent with CF (higher Cl- levels than sodium), not to mention growing out cepacia, pancreatic insufficiency....you get the point. I was 33 (or was it 34?) when I was diagnosed. So yes, go for the extended panel. There are false positives with the sweat test, some disorders such as untreated thyroid disease, Addisons, some neuro disorders (glycogen storage disorders), that can cause a fase high. I have read that there are some healthy individuals without any disorders that have high sweat test results. On the other hand, there are a handful of CF folks who test negative on their sweat tests but their genetic profile says otherwise. Keep in mind that more and more mutations are being discovered all of the time, I know of an individual who was tested a few times with the Ambry panel before her mutations became evident. Apparently as more mutations are found, the test is updated periodically (at least that is what I was told, correct me if I am wrong). I think there are 1300+ mutations at this point, with more being discovered. Hugs, Jenn <img src="i/expressions/face-icon-small-smile.gif" border="0">

 

[JustDucky]

Yes, this has happened to me...I was tested initially with the less extensive panel. Ultimately I was tested with the extended Ambry panel and came up with very rare deletions, less than 1% of the CF population have them. My sweat tests are in the borderline range, 49 and 50 but my ratios were consistent with CF (higher Cl- levels than sodium), not to mention growing out cepacia, pancreatic insufficiency....you get the point. I was 33 (or was it 34?) when I was diagnosed. So yes, go for the extended panel. There are false positives with the sweat test, some disorders such as untreated thyroid disease, Addisons, some neuro disorders (glycogen storage disorders), that can cause a fase high. I have read that there are some healthy individuals without any disorders that have high sweat test results. On the other hand, there are a handful of CF folks who test negative on their sweat tests but their genetic profile says otherwise. Keep in mind that more and more mutations are being discovered all of the time, I know of an individual who was tested a few times with the Ambry panel before her mutations became evident. Apparently as more mutations are found, the test is updated periodically (at least that is what I was told, correct me if I am wrong). I think there are 1300+ mutations at this point, with more being discovered. Hugs, Jenn <img src="i/expressions/face-icon-small-smile.gif" border="0">

 

[JustDucky]

Yes, this has happened to me...I was tested initially with the less extensive panel. Ultimately I was tested with the extended Ambry panel and came up with very rare deletions, less than 1% of the CF population have them. My sweat tests are in the borderline range, 49 and 50 but my ratios were consistent with CF (higher Cl- levels than sodium), not to mention growing out cepacia, pancreatic insufficiency....you get the point. I was 33 (or was it 34?) when I was diagnosed. So yes, go for the extended panel. There are false positives with the sweat test, some disorders such as untreated thyroid disease, Addisons, some neuro disorders (glycogen storage disorders), that can cause a fase high. I have read that there are some healthy individuals without any disorders that have high sweat test results. On the other hand, there are a handful of CF folks who test negative on their sweat tests but their genetic profile says otherwise. Keep in mind that more and more mutations are being discovered all of the time, I know of an individual who was tested a few times with the Ambry panel before her mutations became evident. Apparently as more mutations are found, the test is updated periodically (at least that is what I was told, correct me if I am wrong). I think there are 1300+ mutations at this point, with more being discovered. Hugs, Jenn <img src="i/expressions/face-icon-small-smile.gif" border="0">

 

[Alyssa]

It's usually the other way around but not always -- people test negative on a sweat test but then positive on a gene test. But there certainly is no reason to believe your doctor isn't on the right path. He sounds like a great doctor to me, since he still wants to do a full panel.

I think it is poitless to test for anything less than all the genes -- What good does it do if you can still miss 10% of the possible gene combinations?

If you test negative on both a full genetic test and sweat test, you can ask for a nasal potential test. But that's not usually done on small kids just because it takes a little bit of time (30 minutes or so) and is kind of uncomfortable (involves tubes being up the nasel passage and then a slow drip of saline solution running out the nose). It also is not available everywhere. It is used when you clearly have CF symptoms but do not test positive any other way.

It is not unusual for doctors to want to have both a sweat test & gene test. It feels more complete for them. You are the right path in getting full testing and getting established with a CF clinic.

 

[Alyssa]

It's usually the other way around but not always -- people test negative on a sweat test but then positive on a gene test. But there certainly is no reason to believe your doctor isn't on the right path. He sounds like a great doctor to me, since he still wants to do a full panel.

I think it is poitless to test for anything less than all the genes -- What good does it do if you can still miss 10% of the possible gene combinations?

If you test negative on both a full genetic test and sweat test, you can ask for a nasal potential test. But that's not usually done on small kids just because it takes a little bit of time (30 minutes or so) and is kind of uncomfortable (involves tubes being up the nasel passage and then a slow drip of saline solution running out the nose). It also is not available everywhere. It is used when you clearly have CF symptoms but do not test positive any other way.

It is not unusual for doctors to want to have both a sweat test & gene test. It feels more complete for them. You are the right path in getting full testing and getting established with a CF clinic.

 

[Alyssa]

It's usually the other way around but not always -- people test negative on a sweat test but then positive on a gene test. But there certainly is no reason to believe your doctor isn't on the right path. He sounds like a great doctor to me, since he still wants to do a full panel.

I think it is poitless to test for anything less than all the genes -- What good does it do if you can still miss 10% of the possible gene combinations?

If you test negative on both a full genetic test and sweat test, you can ask for a nasal potential test. But that's not usually done on small kids just because it takes a little bit of time (30 minutes or so) and is kind of uncomfortable (involves tubes being up the nasel passage and then a slow drip of saline solution running out the nose). It also is not available everywhere. It is used when you clearly have CF symptoms but do not test positive any other way.

It is not unusual for doctors to want to have both a sweat test & gene test. It feels more complete for them. You are the right path in getting full testing and getting established with a CF clinic.

 

[okok]

I can understand why the sweat test has such a bad rap. DD initially had a negative sweat test. However I still think the sweat test is a valuable diagnostic tool and that it will remain important for quite some time. It is important that it is done correctly and that the results of the sweat test be interpreted with careful consideration to the patient's symptoms and with an awareness that false negatives can occur in cases where a patient is malnourished or has low sodium and that some cfers simply have lower sweat chloride concentrations. As cepaciagal and Jazzy's mom point out, genetic tests are not able to dectect unknown mutations. Our DNA always has the potential to become mutated and when it occurs in a germ cell we pass these mutations on to our childern. For this reason, new CFTR mutations can be occuring at this very moment. Of course, these mutations will be extremely rare but there may always be 1 or two people in the world with an unknown CF mutation. For this reason the sweat test is important in diagnosing these patients and discovering new/previously unknown mutations.

Anyway i wish you the best of luck. If the sweat test turns out negative you'll probably want to suggest full genetic testing from ambry so that your mind can rest.

Let us know how the sweat test goes. I'll be hoping for a negative and an eventual diagnosis of no cf.

 

[okok]

I can understand why the sweat test has such a bad rap. DD initially had a negative sweat test. However I still think the sweat test is a valuable diagnostic tool and that it will remain important for quite some time. It is important that it is done correctly and that the results of the sweat test be interpreted with careful consideration to the patient's symptoms and with an awareness that false negatives can occur in cases where a patient is malnourished or has low sodium and that some cfers simply have lower sweat chloride concentrations. As cepaciagal and Jazzy's mom point out, genetic tests are not able to dectect unknown mutations. Our DNA always has the potential to become mutated and when it occurs in a germ cell we pass these mutations on to our childern. For this reason, new CFTR mutations can be occuring at this very moment. Of course, these mutations will be extremely rare but there may always be 1 or two people in the world with an unknown CF mutation. For this reason the sweat test is important in diagnosing these patients and discovering new/previously unknown mutations.

Anyway i wish you the best of luck. If the sweat test turns out negative you'll probably want to suggest full genetic testing from ambry so that your mind can rest.

Let us know how the sweat test goes. I'll be hoping for a negative and an eventual diagnosis of no cf.

 

[okok]

I can understand why the sweat test has such a bad rap. DD initially had a negative sweat test. However I still think the sweat test is a valuable diagnostic tool and that it will remain important for quite some time. It is important that it is done correctly and that the results of the sweat test be interpreted with careful consideration to the patient's symptoms and with an awareness that false negatives can occur in cases where a patient is malnourished or has low sodium and that some cfers simply have lower sweat chloride concentrations. As cepaciagal and Jazzy's mom point out, genetic tests are not able to dectect unknown mutations. Our DNA always has the potential to become mutated and when it occurs in a germ cell we pass these mutations on to our childern. For this reason, new CFTR mutations can be occuring at this very moment. Of course, these mutations will be extremely rare but there may always be 1 or two people in the world with an unknown CF mutation. For this reason the sweat test is important in diagnosing these patients and discovering new/previously unknown mutations.

Anyway i wish you the best of luck. If the sweat test turns out negative you'll probably want to suggest full genetic testing from ambry so that your mind can rest.

Let us know how the sweat test goes. I'll be hoping for a negative and an eventual diagnosis of no cf.

 

[Catiesmom]

Thanks! Our doctor has already sent out for the expanded panel, so hopefully we'll have those results soon after the sweat test is done.

 

[Catiesmom]

Thanks! Our doctor has already sent out for the expanded panel, so hopefully we'll have those results soon after the sweat test is done.