Inheriting 2 defective genes from one parent?

candi81

New member
My son who is now 11 weeks had a 'borderline' result from his newborn screening. The followup sweat test was also borderline. I knew I was a carrier (found out while pregnant that I carried the delta f508.) But my husbands screening came back normal, so I was told while I was pregnant there was no chance of him having it. So why is he having these results? They just finished genetic testing on him, and sure enough they found 2 mutations...delta f508 and one more (I was too tore up and forgot which one) But the pediatrician still says he can't diagnose him with CF until both my husband and I complete the same genetic testing. He said there was a chance he inherited both defective copies from me and not his father...and if this were the case, he would only be a carrier and not have it. I've never heard of this before. Is it possible for someone to pass on 2 genes? Also, woudln't that mean that I would actually have to 'have' the disease? I'm just very torn up right now and seeking information. The Dr said he personally felt that both genes came from me, but he can't say until we do the genetic testing. Anyone else have a situation like this?
 

candi81

New member
My son who is now 11 weeks had a 'borderline' result from his newborn screening. The followup sweat test was also borderline. I knew I was a carrier (found out while pregnant that I carried the delta f508.) But my husbands screening came back normal, so I was told while I was pregnant there was no chance of him having it. So why is he having these results? They just finished genetic testing on him, and sure enough they found 2 mutations...delta f508 and one more (I was too tore up and forgot which one) But the pediatrician still says he can't diagnose him with CF until both my husband and I complete the same genetic testing. He said there was a chance he inherited both defective copies from me and not his father...and if this were the case, he would only be a carrier and not have it. I've never heard of this before. Is it possible for someone to pass on 2 genes? Also, woudln't that mean that I would actually have to 'have' the disease? I'm just very torn up right now and seeking information. The Dr said he personally felt that both genes came from me, but he can't say until we do the genetic testing. Anyone else have a situation like this?
 

candi81

New member
My son who is now 11 weeks had a 'borderline' result from his newborn screening. The followup sweat test was also borderline. I knew I was a carrier (found out while pregnant that I carried the delta f508.) But my husbands screening came back normal, so I was told while I was pregnant there was no chance of him having it. So why is he having these results? They just finished genetic testing on him, and sure enough they found 2 mutations...delta f508 and one more (I was too tore up and forgot which one) But the pediatrician still says he can't diagnose him with CF until both my husband and I complete the same genetic testing. He said there was a chance he inherited both defective copies from me and not his father...and if this were the case, he would only be a carrier and not have it. I've never heard of this before. Is it possible for someone to pass on 2 genes? Also, woudln't that mean that I would actually have to 'have' the disease? I'm just very torn up right now and seeking information. The Dr said he personally felt that both genes came from me, but he can't say until we do the genetic testing. Anyone else have a situation like this?
 

candi81

New member
My son who is now 11 weeks had a 'borderline' result from his newborn screening. The followup sweat test was also borderline. I knew I was a carrier (found out while pregnant that I carried the delta f508.) But my husbands screening came back normal, so I was told while I was pregnant there was no chance of him having it. So why is he having these results? They just finished genetic testing on him, and sure enough they found 2 mutations...delta f508 and one more (I was too tore up and forgot which one) But the pediatrician still says he can't diagnose him with CF until both my husband and I complete the same genetic testing. He said there was a chance he inherited both defective copies from me and not his father...and if this were the case, he would only be a carrier and not have it. I've never heard of this before. Is it possible for someone to pass on 2 genes? Also, woudln't that mean that I would actually have to 'have' the disease? I'm just very torn up right now and seeking information. The Dr said he personally felt that both genes came from me, but he can't say until we do the genetic testing. Anyone else have a situation like this?
 

candi81

New member
My son who is now 11 weeks had a 'borderline' result from his newborn screening. The followup sweat test was also borderline. I knew I was a carrier (found out while pregnant that I carried the delta f508.) But my husbands screening came back normal, so I was told while I was pregnant there was no chance of him having it. So why is he having these results? They just finished genetic testing on him, and sure enough they found 2 mutations...delta f508 and one more (I was too tore up and forgot which one) But the pediatrician still says he can't diagnose him with CF until both my husband and I complete the same genetic testing. He said there was a chance he inherited both defective copies from me and not his father...and if this were the case, he would only be a carrier and not have it. I've never heard of this before. Is it possible for someone to pass on 2 genes? Also, woudln't that mean that I would actually have to 'have' the disease? I'm just very torn up right now and seeking information. The Dr said he personally felt that both genes came from me, but he can't say until we do the genetic testing. Anyone else have a situation like this?
 

just1more

New member
First of all, I'm sorry about the news, and that if the diagnosis is confirmed, that you chose to make an online home here.

To answer your question: No, it is not feasible to pass 2 genes from the same parent, this is basic genetics. I'm not a geneticist so if someone can refute this please do with with sources.

That said, there are a couple of possibilites I see. I list them in what I would think is likelihood:

1) You husband is a carrier of a rarer CF mutation as there are 1500 of them, and most likely he was tested for the top 100 or so. Confirming will be pretty easy as they know which to check for (your son's).

2) A spontaneous mutation could have occured. While rarer, it is possible that during the split/join/grow process in a embryo that a gene can mutate all on its own. Otherwise, there would be no CF mutations in the first place (where did the 1st cases get it).

Regardless, if your son has 2 genes, he has CF. Any Dr that says otherwise should be very suspect. There is no need to test ANYONE to confirm this diagnosis if there are 2 mutations. Now, it is possible that the one from your husband is rare and either unknown in impact, or considered non-disease causing. However, the genetic test on your son is conclusive.

BUT, having 2 genes does not predict outcome. It is possible for siblings with the same mutations to have drastically different presentations and issues.
 

just1more

New member
First of all, I'm sorry about the news, and that if the diagnosis is confirmed, that you chose to make an online home here.

To answer your question: No, it is not feasible to pass 2 genes from the same parent, this is basic genetics. I'm not a geneticist so if someone can refute this please do with with sources.

That said, there are a couple of possibilites I see. I list them in what I would think is likelihood:

1) You husband is a carrier of a rarer CF mutation as there are 1500 of them, and most likely he was tested for the top 100 or so. Confirming will be pretty easy as they know which to check for (your son's).

2) A spontaneous mutation could have occured. While rarer, it is possible that during the split/join/grow process in a embryo that a gene can mutate all on its own. Otherwise, there would be no CF mutations in the first place (where did the 1st cases get it).

Regardless, if your son has 2 genes, he has CF. Any Dr that says otherwise should be very suspect. There is no need to test ANYONE to confirm this diagnosis if there are 2 mutations. Now, it is possible that the one from your husband is rare and either unknown in impact, or considered non-disease causing. However, the genetic test on your son is conclusive.

BUT, having 2 genes does not predict outcome. It is possible for siblings with the same mutations to have drastically different presentations and issues.
 

just1more

New member
First of all, I'm sorry about the news, and that if the diagnosis is confirmed, that you chose to make an online home here.

To answer your question: No, it is not feasible to pass 2 genes from the same parent, this is basic genetics. I'm not a geneticist so if someone can refute this please do with with sources.

That said, there are a couple of possibilites I see. I list them in what I would think is likelihood:

1) You husband is a carrier of a rarer CF mutation as there are 1500 of them, and most likely he was tested for the top 100 or so. Confirming will be pretty easy as they know which to check for (your son's).

2) A spontaneous mutation could have occured. While rarer, it is possible that during the split/join/grow process in a embryo that a gene can mutate all on its own. Otherwise, there would be no CF mutations in the first place (where did the 1st cases get it).

Regardless, if your son has 2 genes, he has CF. Any Dr that says otherwise should be very suspect. There is no need to test ANYONE to confirm this diagnosis if there are 2 mutations. Now, it is possible that the one from your husband is rare and either unknown in impact, or considered non-disease causing. However, the genetic test on your son is conclusive.

BUT, having 2 genes does not predict outcome. It is possible for siblings with the same mutations to have drastically different presentations and issues.
 

just1more

New member
First of all, I'm sorry about the news, and that if the diagnosis is confirmed, that you chose to make an online home here.

To answer your question: No, it is not feasible to pass 2 genes from the same parent, this is basic genetics. I'm not a geneticist so if someone can refute this please do with with sources.

That said, there are a couple of possibilites I see. I list them in what I would think is likelihood:

1) You husband is a carrier of a rarer CF mutation as there are 1500 of them, and most likely he was tested for the top 100 or so. Confirming will be pretty easy as they know which to check for (your son's).

2) A spontaneous mutation could have occured. While rarer, it is possible that during the split/join/grow process in a embryo that a gene can mutate all on its own. Otherwise, there would be no CF mutations in the first place (where did the 1st cases get it).

Regardless, if your son has 2 genes, he has CF. Any Dr that says otherwise should be very suspect. There is no need to test ANYONE to confirm this diagnosis if there are 2 mutations. Now, it is possible that the one from your husband is rare and either unknown in impact, or considered non-disease causing. However, the genetic test on your son is conclusive.

BUT, having 2 genes does not predict outcome. It is possible for siblings with the same mutations to have drastically different presentations and issues.
 

just1more

New member
First of all, I'm sorry about the news, and that if the diagnosis is confirmed, that you chose to make an online home here.
<br />
<br />To answer your question: No, it is not feasible to pass 2 genes from the same parent, this is basic genetics. I'm not a geneticist so if someone can refute this please do with with sources.
<br />
<br />That said, there are a couple of possibilites I see. I list them in what I would think is likelihood:
<br />
<br />1) You husband is a carrier of a rarer CF mutation as there are 1500 of them, and most likely he was tested for the top 100 or so. Confirming will be pretty easy as they know which to check for (your son's).
<br />
<br />2) A spontaneous mutation could have occured. While rarer, it is possible that during the split/join/grow process in a embryo that a gene can mutate all on its own. Otherwise, there would be no CF mutations in the first place (where did the 1st cases get it).
<br />
<br />Regardless, if your son has 2 genes, he has CF. Any Dr that says otherwise should be very suspect. There is no need to test ANYONE to confirm this diagnosis if there are 2 mutations. Now, it is possible that the one from your husband is rare and either unknown in impact, or considered non-disease causing. However, the genetic test on your son is conclusive.
<br />
<br />BUT, having 2 genes does not predict outcome. It is possible for siblings with the same mutations to have drastically different presentations and issues.
 
M

Mommafirst

Guest
Well it is possible (though unlikely) to pass 2 genes from one parent IF both of those CF genes are on the same allele. Meaning you have 2 CF genes from one parent passed to you, you don't have CF but you are like a double carrier. This is very very rare, but they did do my genetics when my daughter was diagnosed to make sure that wasn't the case. It wasn't.

Chances are much better that your husband wasn't really properly screened during pregnancy. Most OBs don't realize that to truly rule out CF carrier status you need to check for all 1500+ mutations. Sadly, there are others here who have also thought they were in the clear and then abruptly shocked by the diagnosis of their child.

Hang in there. The early days of diagnosis are confusing and emotionally taxing -- wherever this is taking you, it will get easier.
 
M

Mommafirst

Guest
Well it is possible (though unlikely) to pass 2 genes from one parent IF both of those CF genes are on the same allele. Meaning you have 2 CF genes from one parent passed to you, you don't have CF but you are like a double carrier. This is very very rare, but they did do my genetics when my daughter was diagnosed to make sure that wasn't the case. It wasn't.

Chances are much better that your husband wasn't really properly screened during pregnancy. Most OBs don't realize that to truly rule out CF carrier status you need to check for all 1500+ mutations. Sadly, there are others here who have also thought they were in the clear and then abruptly shocked by the diagnosis of their child.

Hang in there. The early days of diagnosis are confusing and emotionally taxing -- wherever this is taking you, it will get easier.
 
M

Mommafirst

Guest
Well it is possible (though unlikely) to pass 2 genes from one parent IF both of those CF genes are on the same allele. Meaning you have 2 CF genes from one parent passed to you, you don't have CF but you are like a double carrier. This is very very rare, but they did do my genetics when my daughter was diagnosed to make sure that wasn't the case. It wasn't.

Chances are much better that your husband wasn't really properly screened during pregnancy. Most OBs don't realize that to truly rule out CF carrier status you need to check for all 1500+ mutations. Sadly, there are others here who have also thought they were in the clear and then abruptly shocked by the diagnosis of their child.

Hang in there. The early days of diagnosis are confusing and emotionally taxing -- wherever this is taking you, it will get easier.
 
M

Mommafirst

Guest
Well it is possible (though unlikely) to pass 2 genes from one parent IF both of those CF genes are on the same allele. Meaning you have 2 CF genes from one parent passed to you, you don't have CF but you are like a double carrier. This is very very rare, but they did do my genetics when my daughter was diagnosed to make sure that wasn't the case. It wasn't.

Chances are much better that your husband wasn't really properly screened during pregnancy. Most OBs don't realize that to truly rule out CF carrier status you need to check for all 1500+ mutations. Sadly, there are others here who have also thought they were in the clear and then abruptly shocked by the diagnosis of their child.

Hang in there. The early days of diagnosis are confusing and emotionally taxing -- wherever this is taking you, it will get easier.
 
M

Mommafirst

Guest
Well it is possible (though unlikely) to pass 2 genes from one parent IF both of those CF genes are on the same allele. Meaning you have 2 CF genes from one parent passed to you, you don't have CF but you are like a double carrier. This is very very rare, but they did do my genetics when my daughter was diagnosed to make sure that wasn't the case. It wasn't.
<br />
<br />Chances are much better that your husband wasn't really properly screened during pregnancy. Most OBs don't realize that to truly rule out CF carrier status you need to check for all 1500+ mutations. Sadly, there are others here who have also thought they were in the clear and then abruptly shocked by the diagnosis of their child.
<br />
<br />Hang in there. The early days of diagnosis are confusing and emotionally taxing -- wherever this is taking you, it will get easier.
 

hmw

New member
If you read Gramma58's thread on this forum, you'll see a very specific example of how someone passed on 2 mutations to their baby to better understand it. It's not common but it can happen.

If you passed on both mutations, you would still be a carrier, despite having 2 mutations. This would be because you only passed one of your CFTR genes to your baby. You still have another one; since both of them need to have a mutation to have CF you would be a carrier.

Before this is assumed, though, the dr. is right- both you and your dh need to have the full test since odds are much higher that it's one of the rare mutations that wasn't caught in your husband's initial test & he's the carrier (which would mean your son has cf.) Ambry even offers a mutation-specific test that can check both of you only for your son's 2nd mutation to see which of you has it.

I would also take into consideration... since you were assured that your baby would not have CF during your pregnancy, what led them to do a sweat test after he was born? Is he exhibiting worrisome symptoms? That would come into play too in this situation... I hope this is figured out soon so he can start treatment right away if needed or your mind can be put at ease if he doesn't have cf!
 

hmw

New member
If you read Gramma58's thread on this forum, you'll see a very specific example of how someone passed on 2 mutations to their baby to better understand it. It's not common but it can happen.

If you passed on both mutations, you would still be a carrier, despite having 2 mutations. This would be because you only passed one of your CFTR genes to your baby. You still have another one; since both of them need to have a mutation to have CF you would be a carrier.

Before this is assumed, though, the dr. is right- both you and your dh need to have the full test since odds are much higher that it's one of the rare mutations that wasn't caught in your husband's initial test & he's the carrier (which would mean your son has cf.) Ambry even offers a mutation-specific test that can check both of you only for your son's 2nd mutation to see which of you has it.

I would also take into consideration... since you were assured that your baby would not have CF during your pregnancy, what led them to do a sweat test after he was born? Is he exhibiting worrisome symptoms? That would come into play too in this situation... I hope this is figured out soon so he can start treatment right away if needed or your mind can be put at ease if he doesn't have cf!
 

hmw

New member
If you read Gramma58's thread on this forum, you'll see a very specific example of how someone passed on 2 mutations to their baby to better understand it. It's not common but it can happen.

If you passed on both mutations, you would still be a carrier, despite having 2 mutations. This would be because you only passed one of your CFTR genes to your baby. You still have another one; since both of them need to have a mutation to have CF you would be a carrier.

Before this is assumed, though, the dr. is right- both you and your dh need to have the full test since odds are much higher that it's one of the rare mutations that wasn't caught in your husband's initial test & he's the carrier (which would mean your son has cf.) Ambry even offers a mutation-specific test that can check both of you only for your son's 2nd mutation to see which of you has it.

I would also take into consideration... since you were assured that your baby would not have CF during your pregnancy, what led them to do a sweat test after he was born? Is he exhibiting worrisome symptoms? That would come into play too in this situation... I hope this is figured out soon so he can start treatment right away if needed or your mind can be put at ease if he doesn't have cf!
 

hmw

New member
If you read Gramma58's thread on this forum, you'll see a very specific example of how someone passed on 2 mutations to their baby to better understand it. It's not common but it can happen.

If you passed on both mutations, you would still be a carrier, despite having 2 mutations. This would be because you only passed one of your CFTR genes to your baby. You still have another one; since both of them need to have a mutation to have CF you would be a carrier.

Before this is assumed, though, the dr. is right- both you and your dh need to have the full test since odds are much higher that it's one of the rare mutations that wasn't caught in your husband's initial test & he's the carrier (which would mean your son has cf.) Ambry even offers a mutation-specific test that can check both of you only for your son's 2nd mutation to see which of you has it.

I would also take into consideration... since you were assured that your baby would not have CF during your pregnancy, what led them to do a sweat test after he was born? Is he exhibiting worrisome symptoms? That would come into play too in this situation... I hope this is figured out soon so he can start treatment right away if needed or your mind can be put at ease if he doesn't have cf!
 

hmw

New member
If you read Gramma58's thread on this forum, you'll see a very specific example of how someone passed on 2 mutations to their baby to better understand it. It's not common but it can happen.
<br />
<br />If you passed on both mutations, you would still be a carrier, despite having 2 mutations. This would be because you only passed one of your CFTR genes to your baby. You still have another one; since both of them need to have a mutation to have CF you would be a carrier.
<br />
<br />Before this is assumed, though, the dr. is right- both you and your dh need to have the full test since odds are much higher that it's one of the rare mutations that wasn't caught in your husband's initial test & he's the carrier (which would mean your son has cf.) Ambry even offers a mutation-specific test that can check both of you only for your son's 2nd mutation to see which of you has it.
<br />
<br />I would also take into consideration... since you were assured that your baby would not have CF during your pregnancy, what led them to do a sweat test after he was born? Is he exhibiting worrisome symptoms? That would come into play too in this situation... I hope this is figured out soon so he can start treatment right away if needed or your mind can be put at ease if he doesn't have cf!
 
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