are siblings more likely to be PA?

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I always thought there was a genetic link.

But a friend just told us his nephew (brother of PA niece) was recently diagnosed with PA, and he said the doctor had told his brother and SIL that a sibling had no greater probability of being PA than anyone else in the general population.

Has anyone else heard the same thing?

On Aug 23, 2006

My understanding, and this comes from multiple sources, is that the tendency toward allergies is genetic. The actual allergens that a person reacts to is not. So siblings have a greater chance of being allergic to something, but it's no more likely to be peanuts than for any other person who has allergies.

On Aug 23, 2006

there was a british study done about 10 years ago that found 6.9% of siblings of PA children also developed PA.

the percentage is obviously much greater than the general population, but still it is only 7%.

i don't know if there has been any other study done since.

On Aug 23, 2006

I dont have the source... but if one parent has an allergy then a child is, like around, 40% chance of having SOME allergy.

If 2 parents have allergies, it jumps drastically (say 80%) or something like that.

Numbers MAY be off... but the numbers are high IIRC.

Jason

------------------ [b]* Obsessed * [/b]

ETA: I was close:

A family history of allergies is the single most important factor that predisposes a person to develop allergic disease. If one parent has allergic disease, the estimated risk of the child to develop allergies is 48%; the child's risk grows to 70% if both parents have allergies

[url="http://www.aaaai.org/springallergy/pediatric_allergies.stm"]http://www.aaaai.org/springallergy/pediatric_allergies.stm[/url]

[This message has been edited by jtolpin (edited August 23, 2006).]

On Aug 23, 2006

I was told the same as JimmysMom, that siblings have a greater risk of food allergies, they have the risk of the allergies being higher, but not having the actual allergy of the 1st child with allergies. I was told this by 2 allergists and a pediatrician. Yet, my son has no food allergies that we know of...he has born with a milk allergy but outgrew it before his 1st birthday. He has been tested for all nuts, eggs, milk, shelfish, and the other major food allergens as well as outdoor allergies and he does have only a mountain cedar allergy. Then again, just about all of Texas is allergic to cedar [img]http://uumor.pair.com/nutalle2/peanutallergy/smile.gif[/img]

------------------ Helen Mom to Alyssa (PA, age 6) Mom to Theodore (age 3)

[This message has been edited by TeddyAlly (edited August 23, 2006).]

On Aug 23, 2006

(This is just my opinion, okay-- could be totally wrong here, but "atopy" is unlikely to be a single gene or even a single allele...)

While I know where the stats Jason quote come from, I also feel very strongly that these are just averages. I think that either number probably is really about +/- 20%. In a family where about one in three people have either childhood eczema or adult hayfever, well. Clearly this counts as a "family history of atopy." Can a PA or brittle asthma come from such a family? Of course. And in those families, it probably seems like such a severe atopic condition "comes out of nowhere."

But just as clearly, it isn't the same genetic risk in my family. No matter how you slice it, there is [i]not one person[/i] in either my extended family or DH's that doesn't have at least one major atopic condition, and a majority have at least two. I consider [i]that[/i] a genetic inevitability. Can you win the lottery and not be atopic in such a family? I'm not sure. Maybe.

But you definitely cannot predict what form any particular allergies will take. I think that anecdotally, there must be a genetic profile that contributes very heavily to a predisposition toward a particular [i]class[/i] of allergies, which is why PA sibs have a higher risk of a PA than even other atopic people. It also explains why some families have a tendency toward anaphylactic allergies (like mine). What I think that means is that a PA sibling is likely to have another ana. FA or a medication or insect venom allergy.

It's that good old Mendelevian luck-o-the-draw. [img]http://uumor.pair.com/nutalle2/peanutallergy/wink.gif[/img]

On Aug 23, 2006

When my daughter who is 8 was 1 she would break out in a rash on her face every time she would eat PB. We were living in Korea at the time and when I called the Dr he said do not worry about that just try it again in a week. Well I did and the same thing happened. I didn't give it to her again for about another year and then it didn't happpen. She was allergic to egg at the time, but didn't know allergies were serious. My nephew was also allergic to PB and eggs, but also outgrown. Now my 2 yr old son is allergic to PB and egg white only now. So I do think there is something genetic to it. I was allergic to tomatoes and egg as a baby and my mom was allergic to Penicilin.

On Aug 23, 2006

I don't care what the numbers say (and they do say about 7% chance for sibling). I have an EXTREMELY mild milk allergy and mild asthma that really is only a problem during pregnancy for me. DH has environmental allergies but takes claritin maybe 6 times a year before cutting grass...obviously not that bad. Doesn't seem like a family at high risk for severe food allergy.

DS#2 was exposed to pnut and walnut only through the first 6 weeks or so of breastfeeding. Tested negative via RAST at 1 and 2 years old and then turns up a class 3 and 4 RAST respectively with a 3+ on pnut scratch at almost 4 years of age. No known rxn or ingestion ever. Somehow we were genetically destined to deal with this. Even my dr didn't believe it. Goes to show what they know about how PA develops. HA!

Luvmyboys edited to say...sorry. I didn't point out that ds#1 is PA as well

[This message has been edited by luvmyboys (edited August 24, 2006).]

On Aug 23, 2006

Thank you for all the replies. From all your thoughts I am getting that any allergies in a family tends to predispose for allergies, not necessarily for the same allergen?!?!?

Am I getting that right?

On Aug 23, 2006

Hi, What I have gathered in my research is that they may a predisposition to allergies, but that the allergies may all be different. ie: My husband is from New Zealand and we found out 3 years ago that he is yellow jacket allergic(anaphylactic). I just assumed that he being from another county doesn't have the immunities we have living in North America. Anyway, 10 years ago my oldest was found to be PA. At this time there was NO fanily history of any kind for allergies. I could drink poison and be fine. Well, I had my second child at 2yrs tested for PA and it was neg. Now, she had had no exposire to peanuts. Well, when she was 4.5 yrs I gave a cashew that was NOT cooked in peanut oil--she had anaphy. and ended up in the ambulance on the way to hospital. My oldest son was at home and I didn't have an epi with me, and to be quite honest I didn't know she was reacting at first. I just never dreamed...I did not have her tested for TNA at the initial appointment. Anyway, 1st child PA, 2nd child TNA. Now I have a third child who was just tested for PA and TNA and she has both. GO figure! I was told in the beginning that another one of my children having PA or TNA or any FA wasn't any greater risk than any other child. Now, I have my own theories. I ate peanuts like crazy when I was pregnant and nursing my first. Then, when I was pregnant with the 2nd I ate NO peanuts and all I ate was some cashew and almonds for snacks(still didn't eat them around my PA child, too paranoid), anyway, she turns out to be most allergic to cashews and almonds. Then 3rd child, when I was pregnant of course NO nuts of anykind, and in fact I was careful not to eat too much of any one thing (soy etc..). Nursed her for 2 years like the others and she has PA and TNA. So, who knows exactly. This is just my story--I still think it is bizzare . I do think that there is a predisposition to allergies in general, and predisposition to severe anaphylactic reactions as well.

------------------ Stacie - Mother to: 10 yr. PA 8 yr. TNA 2.5 yr. PA&TNA

On Aug 23, 2006

Our daughter has voluntarily avoided peanuts since her brothers diagnosis. They are grown, she 24, he almost 22.

She is also aware of the risk to her future children so she plans on avoiding peanuts for as long as she has to.

peg

On Aug 23, 2006

not sure. but two of my three girls (the two with husband #2, who incidentally has treenut allergies) have the exact same food allergies, including serous PA. i'd say it's likely for siblings to have PA but i'd say the risk may be different for half-siblings. i say this because our two children from prior marriages (one his, one hers) have no fa's at all. i chalk it up to our genetic combination. i lovingly call my two youngest girls our "mutants." fortunately, they find humor in that. [img]http://uumor.pair.com/nutalle2/peanutallergy/smile.gif[/img]

On Aug 23, 2006

One out of three children here. No nieces or nephews have it either.

My mother and grandmother have/had food allergies though.

best wishes,

------------------ Renee

today is the tomorrow that you were worried about yesterday.

On Aug 24, 2006

I believe in the genetics idea. We have two pa dd's and there is no history of food allergies, or any allergies in our family. How did they get this? I don't know. Yes I did eat pb while pregnant and bf, but not one quarter the amount my friend did while she was pregnant and bf (also no history of allergies), her children are not pa. I believe that my girls would have had this allergy regardless of what I did or didn't do. We have been told by our ped. that our ds, who is one, has about a 70% of developing pa. I'm rooting for the other 30%. Cheers, Gilli

On Aug 24, 2006

In other words, 'they' say the genetic link is for allergies in general, not a specific allergy. But I think some of us who have had 'odd' experiences suspect that there is also a link for at least severe food allergy, if not PA as well...at least for some of us.

SOME people may only have a genetic predisposition or allergies and bad luck and circumstance made it PA. For my family I think we must have a 'PA gene'. Or at least a 'severe allergy gene' and since we don't eat fish and shellfish...lucky us we got PA and TNA. Luvmyboys

On Aug 24, 2006

No one in our family, siblings, us, grandparents, aunts, uncles, great aunts, great uncles, great cousins (well over 100 people) have PA. A few have seasonal allergies or drug allergies...but no substantial food allergies.

It would make sense to me that there was a possibility for a slightly increased chance of FA based on FA being an auto-immune response, and auto-immune issues often have a genetic component.

I would imagine the greater 'sign' that there is a chance for a PA or other food allergies would be severe eczema or acid reflux as a baby.

On Aug 24, 2006

Jason is the only PA child out of my 4 (so far).

Joey is NKFA, and has eaten peanut products with no problems (at school, not at home)

Allison is MFA, but RAST - to peanut.

Ryan is too young to tell

------------------ Cheryl, mom to Jason (8 MFA including peanuts, tree nuts, shellfish and egg) Joey (6 NKA) Allison (3 MFA including milk, butternut squash, several fruits and suspected shellfish allergies, avoiding tree nuts, RAST - for peanut) Ryan (born 12/27/05) nka *knock on wood*

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