Yesterday I stumbled on a celiac site (http://celiac.com) and read some of the scientific papers they archive, including one going back to 1890 or so. Now I find my mind is integrating a lot of it with other input, such as:
climate data - the timing of our current era, the Holocene, and the development of agriculture
agriculture and what it meant to culture and peoples
my own personal health history and some of the mysteries of our family's health stories
my linguistics background
my fascination with the migrations of peoples
being Irish
and I find that there's a story emerging here. It will take me too long to write it to include it here, but just know that gluten intolerance or out and out allergy is hereditary, and that gluten can cause mental as well as physical responses, pain, obesity, and diabetes, and permanent damage can be done to the small intestine that will interfere with nutrient absorption (and probably cause obesity) for the rest of one's life.
So the bottom line is that I am going to write a book called (working title): Food, Climate, and Migration: The Story of Your Health.
I believe this is serious stuff for our family, and I also think that I can see the genetic patterns emerging among the grandchildren in terms of gene contributions from their parents. But more on this another day. PL
Subscribe to:
Post Comments (Atom)
19 comments:
What a great idea! How does this fit into the timeline?
Genetic patterns for gluten intolerance among the grandchildren?
The story is bigger than I can tell here, but the quick version is this: the population from the Fertile Crescent that developed wheat (by selecting the gluten-bearing varieties) were so healthy that they spread out from that area and overtook the hunter-gatherers that lived in the outlying areas. Two-thirds of the European h/g population was inundated by the farmers' encroachment. The survivors were in the most remote regions where wheat arrived late.
The farmers were gluten-tolerant simply because those who weren't had already died out.
But the h/g populations, especially those in marginal areas such as Ireland, Norway, and Finland, didn't have time to let natural selection sort out those who would survive a wheat diet and those who wouldn't: that's still being sorted out now, in a sense.
So anyone with those genetics, people from areas that did not go through a natural selection for wheat tolerance, carry with them their gluten sensitivity.
Meanwhile in the other continents, other grains were used: millet and sorghum in Africa, maize in Mesoamerica, rice in Asia. None of these contains a protein that causes an inflammatory response, or at least nothing like the chemical responsible for the inflammation eating gluten causes.
In our family we have people who are carrying that gluten sensitivity (the gene FOR it, or the lack of gene to cope w/ it, I'm not clear yet). I am one. Of the two contributions to my gene, one may be G+ (ok for gluten) and one G-, or both mine may be G-. If both are G-, then every one of my children will have one G-, plus whatever D has given them. We don't know his status wrt gluten, so we can't say. If I have one of each, then half my children will have gotten G+ and be ok, and the other half G- and have gluten intolerance. Of course this is statistically speaking.
Now combine that with what the in-law children contribute: each one might or might not have the G+ gene.
Remember that the G+ gene came from the descendants of the group of farmers who spread out from the Fertile Crescent and overran the native populations of Europe (primarily, until N America was overrun much more recently: 500 years as opposed to 3000 years).
So in each family there is one parent who probably has one G- from me, and either a G+ or G- from D. And then there is the spouse who has a good chance, given their family origins, of carrying a G-.
This means that chances are that all the grandkids are G-, with a few exceptions due to a G+ from each parent, and there are a few who are double G-.
These last are the ones who are strongly afflicted with eczema, heavy congestion, yeast infections, and certainly digestive problems and a tendency to get sick.
The guesswork about who carries which gene can be worked backward, too: We can almost certainly guess that D carries one G- at least: Meg was born w/ such severe digestive issues that were so reactive to anything I ate that she could easily be a double G-.
This would then mean that every one of her children has at least one G-. Then if Norman is a double G+ (which is highly unlikely, given his family history), then they would all be just gluten intolerant, but there's some evidence, such as with Brennen, that he might also contribute a G-: his Native American blood would almost guarantee that he has at least one G-.
This means statistically (not that you can apply such statistics to small numbers with any accuracy) that in the 26 grandchildren, if each parent had one G- each (which is highly likely because of where the families came from) you would expect AT BEST 6/7 perfectly normal G+ G+ kids, 6/7 very afflicted with any of the issues I mention above, and 13 who have the tendency but are getting along ok - but who will eventually develop some issues with gluten intolerance.
Or if D is G- G+, then half our kids would inevitably contribute a G- to their kids (because I am double G- in all likelihood), and depending on whether their spouses are G+ G- or double G+, their kids would end up AT BEST 50% seriously afflicted with one of those issues, and 50% gluten intolerant but not currently having difficulties.
The problems of double G- kids show up by the time they are 2. They can affect any part of the body because of inflammation and underlying malnutrition that is not apparent.
It goes on and on.
Twenty percent of the population is gluten intolerant. My guess that it's showing up more profoundly now is because wheat is in everything, not just in bread and pasta - soy sauce, spaghetti sauce, you name it. So kids end up with symptoms and illnesses and aberrations that are hard to pin down and easy to misinterpret: is a cold due to a virus per se, or is it due to the intolerance weaking the immune system?
This is just scratching the surface and I'm just feeling my way along. Just knowing the history of wheat clarifies so much! You can read more about it on http://celiac.com, where I read the article that is the basis for a lot of what I just said. The actual link to it is on my http:grammypegskitchen.blogspot.com post.
There are a few things I'm not clear on/don't understand:
1. You mentioned something about gluten allergy heritability ["gluten intolerance or out and out allergy is hereditary"]. I'd like a reference for this. Something as environmentally sensitive as food allergies can be strongly correlated with family lines without being at all heritable. Studies proving heritability need to be a lot more subtle than "it runs in families." Just curious [I'd like it to be the non-heritable kind of inheritance].
2. Has anyone identified the particular gene that you refer to as G+/-? I haven't done any reading on this but you seemed sketchy on which gene is involved, whether it was a gene prohibiting or allowing proper gluten digestion. I'd think there is a good chance that gluten allergies are a polygenetic phenomenon, involving several genes and/or nongenetic heritable factors. This would make the discussion of the grandkids' chances of getting it very complicated.
3. IF there is a single G-/+ gene, do we know for sure that it works in the way you describe? The gene could be autosomal recessive [the traditional carriers/unaffected/affected], autosomal dominant [you get it or you don't], there could be codominance, etc. etc. Each of these possibilities would drastically change how the gene is expressed in your descendants, and whether or not the gene could be responsible for a spectrum of gluten intolerances. I couldn't tell from your description exactly why type of dominance relationship you are presuming for the G+/- gene.
4. Additionally, gluten intolerance has some strong signs of being degenerative [babies introduced to glutens at young ages supposedly are more likely to get it]. This suggests to me a strong or even dominant environmental cause of the allergy, as opposed to a strictly native cause.
As a model for why I think there might be more to the story than strict heritability, I look at lactose intolerance [which has many of the same selective effects that gluten intolerance would have]. There are a combination of environmental and genetic factors influencing lactose intolerance, even with only one gene involved. I don't know if even this one-gene simplification is true for gluten.
Anyway, I think this is a very crucial topic that you're addressing. It would do our family a lot of good to thoroughly understand this issue. Thanks!
I think that the genetic relationship you are assuming is incomplete dominance. This is when the phenotype expression of the genes is not binary; the presence of one copy does "less" to the phenotype than the presence of a second copy, but still does something. Is this what you had in mind? This would allow for some descendents with no gluten problems, some with minor problems, and some with severe problems [assuming one gene only].
These are all important issues and ones that I am not the least bit clear on, as you have discerned. I stumbled on this story about wheat last night, and you can read the original through the link on my http://grammypegskitchen.blogspot.com article about it. I made up the G+ G- designation just to simplify what I wrote earlier, and I have no real reason to suppose it's one gene. Or that it's not one gene, for that matter.
I am now in the position where I truly want to find out more, even knowing that I don't have time to do that.
I was reading an interesing article on einkorn (early wheat progenitor) on the celiac.com site, pertaining to research on whether it causes the same reactions as later wheat. I was interested to see how early the process of genetic selection by man had occurred, for perfectly good reasons. It all reminded me of Michael Pollan and the discussion of selection that we're doing now and how little we can anticipate the ramifications...
And so on! It's a fascinating business. I encourage you to read the article whose link is posted on Grammy Peg's Kitchen and then tell me what you think.
Thanks for the thoughtful input. I need to know more genetics.
WRT your comment about incomplete dominance, yes, that is what I meant.
If anyone has insights into the barley issue, I'd like to hear about it. The Egyptians cultivated barley for beer and wheat for bread, and later the Irish certainly must have cultivated barley. It has the culprit gliadin just like wheat, I think...
From the [excellent] article you linked:
"Finally gluten intolerance is indeed linked to a specific genetic predisposition: most probably at least two genetic loci are involved in running the risk of intolerance."
Two loci would mean two sets of genes--at minimum--are involved. This complicates things immensely. Assuming an unnaturally simple incomplete dominance relationship [asuming no gene/gene interaction], there are 16 "degrees" of gluten intolerance allowed by two loci. Assuming you and dad both know your alleles, there are still 16 possible sets of gluten-relevant alleles for your kids. With 6 kids and 6 spice, you end up with all 256 possibilities for your grandkids. And this is assuming that you and dad know which genes are relevant and which alleles you both have. You don't. And this is assuming that gluten intolerance is completely genetic, which it isn't.
Of course, the two genes might have some kind of interrelation which makes the number of possible outcomes smaller... but still we could never predict the possibility of your descendants being intolerant!
That's where the retro analysis comes in, or whatever it's called.
I didn't intend the whole thing to be considered deterministic, but knowing that there's this possibility should help, I'd think.
I know that as I suffered through my 30s with migraine after migraine, any idea for relief would have been welcome.
After China I had a very bad summer intestinally speaking and then Sandy suggested I cut out gluten to see what would happen. I rejected the idea because I thought I didn't have the symptoms, but I finally agreed to try it. My life began to turn around that day. No more constant pain, among other things.
So I offer this as something that is interesting and possibly useful.
There's no need for panic if a child did end up gluten-sensitive. If wheat weren't in everything, a low-gluten diet would be really feasible, and the problem wouldn't get out of hand. It's the permanent damage that is done to the small intestine when it's ignored for a long time that is the real problem.
I still think that we have a lot of personal histories among our family reproducing populaton in non-gluten tolerant populations, and anyone who might want to try to go gluten-free for a while might discover relief from one or another issue.
Thx for your helpful comments.
Further response:
I think we have to conclude that gluten intolerance is completely genetic, but also that a baby can get some bad chemistry (vague on purpose, whatever the entity might be...) from the mom during bf. That baby might have problems then and those might have some long-term effects, who can say, and yet not herself be gluten-intolerant. So this bf-induced effect isn't really gluten intolerance.
What other circumstances make you feel that gluten intolerance isn't entirely genetic?
Pete made some of the comments I was going to make. It seems too overly-simplified the way you describe it. Certainly interesting, but being the skeptic I am, I'm not convinced. But as to the genetic concerns, Peter has spoken well (polygenetic, binary, gene identification, etc).
As to another issue, I believe the scripture that says:
16 All grain is good for the afood of man; as also the bfruit of the vine; that which yieldeth fruit, whether in the ground or above the ground—
17 Nevertheless, wheat for man, and corn for the ox, and oats for the horse, and rye for the fowls and for swine, and for all beasts of the field, and barley for all useful animals, and for mild drinks, as also other grain.
I have used this as a guide for nutrition--if I want to be healthy, I eat grains, fruits and vegetables. And the primary grain is wheat.
That's not to say that people don't have a variety of intolerances, alergies, etc, etc, for certain otherwise good foods. However, it does mean that I'm unlikely to omit an otherwise healthful food from my diet without some firm basis for doing so.
I think in the end I also adhere to a personal philosophy of hardiness: eat fully, eat a large variety, tackle life with vigor, and in general you'll do well.
Oh, and one of my reasons for quoting D&C 89 is that I have a problem with a theory that suggests that wheat was good for some people and not for others. I consider it the primary staple for healthy people--the ideal.
And personally, I think you have way too many worthy projects to add another book to the list! SIMPLIFY, SIMPLIFY, SIMPLIFY!!!!
Enjoyed the post,
Chris
The default assumption by necessity is that genes aren't the only cause. From what I understand it is exceedingly rare for genes to have pure deterministic effect without influence from the environment.
Also, given the nature of gluten allergies--your body just not knowing how to digest gluten--I find it hard to imagine that degenerative intolerance could be the result of anything other than environmental factors; informed by genetics, of course. And from my understanding, gluten intolerance is often degenerative. Is this true?
I agree with what Chris says, and I will add that for the rest of us, gluten is positively healthy. It reduces the speed at which wheat flour is digested and thus protects against diabetes and insulin resistance. I have no problem with gluten, so if gluten intolerance is purely genetic then I have absolutely no reason to stay away from it. Right?
Do as you will! I thought this information might be useful to those who wanted to try the very brief experiment it takes to find out if he or she is gluten intolerant or sensitive.
Gluten is not per se healthy. It is a low-quality protein whose chief benefit for those selecting for it was its ability to make big airy loaves of bread.
And whether the genes are deterministic or not, we don't have any idea what the environmental factors are that make a person gluten-intolerant, or sensitive.
Gliadin is the part of gluten that does the damage, apparently, in the people without the gene to handle it. It destroys the villa in the small intestine, giving them a flat surface that is incapable of absorbing nutrients. It also causes a lot of inflammation. This is not like a milk allergy where the enzyme is lacking and so you end up with lots of gas and discomfort: this is actual physical damage, permanent apparently.
I am not trying to persuade anyone to declare themselves gluten-compromised. I simply put this out there as something that I think - or rather thought - you would all benefit from knowing.
But that's not the case!
I'm not sure why some of the writers here are trying to persuade me otherwise!
And going back a few years, I would have declared I wasn't gluten-intolerant, either.
As for the Word of Wisdom, I thought from the header that it was adapted for the weak and weakest...
For me that has meant that these are guidelines for those who have no idea what to do for themselves wrt these substances, and that it is up to us to refine it for our own use according to our experience and acknowledged by the Holy Ghost.
For me this means that even though the Word of Wisdom says every fruit in the season thereof, I don't eat citrus because it gives me a headache and other symptoms.
And I don't eat wheat because it makes me very ill.
And I do eat other grains than those listed, such as millet and quinoa and buckwheat (not a kind of wheat), since they are in the category of 'all grain'.
This seems wise.
It seems sensible to approach the Word of Wisdom this way because it is then in keeping with the rest of the teachings of the church, which are: study it out for yourself, pray about it, and listen for confirmation from the Spirit. The Word of Wisdom gives the basement-level understanding, and then we refine it according to our responsibility to make all decisions, even what we put into our mouths every time we eat, according to our knowledge and confirmation of the Spirit.
And I'd doubt you disagree.
In any case, I am continuing my study, and all I wanted to do with this information was share it with those who might benefit from it, because there is at very least a hereditary link, not only through me but a known one wrt populations: those who received wheat most recently have not had time to sort out who can tolerate it and who can't, the latter presumably dying out (except for modern interventions) as they must have in populations that have had long enough for natural selection to do its culling.
If this were a matter of sneezing or gas, it might not be worth mentioning. But with actual permanent damage being done, I had hoped it would be helpful, or at least thought-provoking.
As you say, there may be 256 gradations of it. That means fewer unscathed, fewer totally scathed, and more with perhaps a little effect. We don't even know it's 2 genes, let alone what different effects those 2 genes have. We just know that more and more people are showing signs of gluten-intolerance, and both blood tests and biopsies are confirming the diagnosis. Some of it is full-blown celiac disease, and some is not. As we apply the Word of Wisdom in every particular, it seems wise to know what might affect us and might not. That's all I had in mind.
This conversation is so totally beyond me right now...I'm just trying to dredge up everything I can remember from my junior year AP biology class to try to follow everything.
But one thought I had that may or may not have anything to do with anything is this. I was watching a PBS special several months ago and they were talking about studying a population of foxes. All the foxes were two varieties of solid colors. And after mating and mating and mating, you still only ended up with statistically predictable variations of those two solid colors.
But during the course of the study, some bombing surrounding WWII happened. And suddenly the foxes started having speckled babies. It was later determined that high doses of adrenaline changed how the genes manifested themselves through phenotype.
So, it was previously though that it was completely genetic. But here you have an environmental factor completely changing everything.
No, it's not all I had in mind: I also thought it was fascinating about the Holocene, the development of agriculture, the spread of populations, etc. And the interesting situation with people on the margins of the dominant culture. Worth sharing, I thought.
That's fascinating!
One thing that I read w/ fascination in The First Word was how mutable and adaptable populations are! It's talking about the development of language but perforce discusses the development of mankind. I'd like something comparable that just tells me about the way things are understood today about genetics - not a text, just some good intelligent interpretation.
This really wasn't supposed to be about the particulars of the way gluten-intolerance is inherited, because that is way beyond me, and apparently not known - I'll have to keep looking. It was a kind of 'hmm this could be happening' comment.
Among the grandkids are various kinds of symptoms of things that are also associated w/ gluten-intolerance. So I thought the various parents might like to find out what I'd learned.
Along w/ the fact that wheat is this unique plant in the history of mankind, with who knows what ramifications.
And not to muddy the waters further, but now I wonder what other transplanted plants might be less well tolerated - or possibly even highly beneficial - to populations that haven't adapted to them.
The milk issue is interesting: dairy developed in many different populations. But not all. In those that needed dairy to survive, only those w/ the enzyme to digest it thrived. But other populations didn't need it at all, and today they don't drink milk.
But most of the lactose goes out w/ the whey in cheese-making, so more populations tolerate cheese, I guess.
And in China they have no cheese but drink copious amounts of milk and drink and eat vast oceans of yogurt.
That's complicated because the World Bank gave them a big donation to help establish dairies.
And the Mongolian peoples were dairy people and their genes are floating around in the north of China quite widely...
I think the wheat thing would not be nearly as big a problem if it weren't in totally weird, hidden places, like ketchup. Probably then the sensitive people would tend to limit the amount of the foods with the offending substance in it without much thought, and the damage would not be being done at the current rate.
But I have a great deal to learn. And biology in my high school was just categorization of species. DNA was discovered only a few years before. AP for us meant 'After Pasteur'. :)
What Real said is the crux of what I was trying to say. It just turns out that genes aren't nearly as deterministic as was once thought; they rely on environmental cues for expression. This is even new since Real took AP Bio, not to mention since grammypeg did, which was, oh, way back then.
I wish I had taken a biology class... ever.
Mom, I think we're all very interested in what you have to say about this. We all think it's important. And it seems apparent that there is a problem with gluten in the family and that it should be understood. But I'm seriously trying to evaluate how panic-worthy this issue is for me and my family. I just don't want you to think that I'm rejecting your point.
On the fascinating subject of genes/environment, I recently read a great book by Matt Ridley called Nature via Nurture. It goes into great detail explaining why and how genes rely on environmental cues for expression. It's worth a read.
It sounds like the book I'm looking for! I'm afraid I'll have to go order it...
By the way, we are building up a nice little library of books that Tro (mostly) is sending our way. If anyone wants to borrow one or more, let me know. They are listed on my http://grammypegskitchen.blogspot.com blog under Shelfari. Or through Shelfari.
As for panic, no. But thoughtful attention, I'd say so.
Meanwhile I'm curious how gliadin destroys villa in the small intestine: is it through the actual destruction of them, as lye would do? Or is it through inflammation and the formation of scar tissue? Or does it somehow reprogram the genetic material so that it changes the intestinal structure? IF there is such a mechanism like this last one, then that suggests other roles for gliadin, or else why would it be so interactive with DNA...
Thanks for the input.
Post a Comment