“Hapsburg Jaw” due to inbreeding? Interesting article...

Question

https://www.eurekalert.org/pub_releases/2019-12/tfg-fdi112719.php

Facial deformity in royal dynasty was linked to inbreeding, scientists confirm

First study to indicate a direct relationship between inbreeding and facial morphology

Comments

There was a recent article in a British newspaper that discusses the tendency for birth defects, some profound, among an ethnic group where cousin marriage, including as close as first cousins, is common. Some statistics presented were that this group accounts a little over 3% of all births in Britain, but is responsible for 30% of all birth defects.

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Some but by no means all birth defects are related to recessive genes . ( other factors  include social deprivation, diet, maternal age ).Much  newspaper reportage in the UK is not always accurate or balanced

https://www.bionews.org.uk/page_92241 gives   the responses of  geneticists and others to one such widely publised piece of reasearch. 

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Helen, some of the related articles listed below the one you referenced were also fascinating.

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Pakistani Britons disproportionately account for birth defects in the British population. In Pakistan itself, something like 60% of all marriages occur between first cousins. The problem is, one set of first cousin marriages isn't likely to create an issue -- it's generation upon generation of cousins marrying, all of whom's parents are themselves cousins, resulting in family trees that do not fork. Unfortunately for the children of such unions, cultural and family pressures perpetuate such marriages. The British documentary "Only Human" (from Dispatches, available on Youtube) goes into this subject in heartbreaking depth.

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It just so happens that one of the books I borrowed this morning from our small town library in Rangiora, Canterbury, New Zealand is:

"She Has Her Mother's Laugh" by Carl Zimmer, published 1918 by Picador.

In the first chapter he describes the Habsburg jaw, and the consequences of the inbreeding.

Answer 1

Thanks Pip, there was also an article from a few years ago that looked at how closely related the Habsburgs were, which came to the conclusion that because of intermarriage between the Austrian and Spanish branches of the family and 3 generations of uncle/niece marriages, the last Spanish Habsburg monarch, Charles II, was more closely related than if his parents had been brother and sister.

Comments

This is bewildering! I’d love to read this article. I’ll go hunting for it. Thanks, John.

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As sad and degenerated as Carlos II was, he isn't the most inbred royal in history. That honor probably goes to Ptolemy XI Alexander II, briefly king of Egypt in 80 BCE. His parents were brother and sister; their parents were uncle and niece. His grandfather and his two great-grandparents were all siblings to each other, all being children of Ptolemy V and Cleopatra I.

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Hi Pip, I think this is the article https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2664480/ it's used as a source on the Wikipedia article for Charles II of Spain https://en.wikipedia.org/wiki/Charles_II_of_Spain

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@Jessica: EGAD!

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Pip, can you imagine how boring dinners must've been in that family? Everyone knows all the same family stories...

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Y’all about family conflicts, jostling for position and such!

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Jessica I think the fact that they lived so far apart meant they had problems coordinating well. Phillip II tried to run everything from Spain but that ended up not working well, and of course it fell apart and he got a reputation for being a cruel reactionary. So if they ever could have got a family dinner it might have helped a lot.

Answer 2

I think it was already commonly understood that inbreeding had played a role in that jaw. For people interested in the inbreeding of the royals in that century, while working on Edward III descents RJ Horace and I counted descents to Phillip and Mary. Keep in mind that we could have started with someone else and ended somewhere else to show the basic pattern 

 https://www.wikitree.com/wiki/Project:Descents_from_Edward_III_to_Phillip_and_Mary

Comments

Nifty charts, Andrew. (Wish WikiTree could produce these.)

Many years ago, I found a book in a rare bookstore, “Genealogical Tables Illustrative of Modern History,” (1875), by Hereford B. George. Pages and pages of royal and aristocratic genealogies. George got it mostly correct, I’d say with about 98% accuracy. His point was to help students to frame history by these families. There are some 54 charts all depending on each other. He included “Christian Dynasties in the East.” I used to read these charts, flipping page after page, and I have to admit that this helped when getting my degree in European History.

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Thanks Pip, I think genealogy is at its best when it helps us  get a feel for history.

Answer 3

Well I thought this was known for a long time, I remember in our nice Time/Life books about that and hemophelia(sp?) being in Royal blood, and those were published in the sixties!

Comments

Hemophilia is not caused by inbreeding. It is caused by a defect on one of the X chromosomes. Because men only have a single X chromosome (barring some rare exceptions) if they are unlucky enough to inherit the defective X from their mother who is a carrier, they will develop hemophilia. A woman may carry the gene on one of her X chromosomes but usually the other X chromosome provides her with the correct gene to make clotting factors. She will still be a carrier and can pass the gene down to her children.

Inbreeding or outbreeding would have made no difference when it comes to the hemophilia gene in Queen Victoria's descendants. Due to the X-linked inheritance factor, male descendants of her daughters would've been at risk of hemophilia regardless of who their fathers were. This is not a disease caused by parents both carrying faulty copies of the same gene.

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I think Navarro was just mentioning what's commonly believed:  A lack of diversity in the gene pool   (I.E.  inbreeding)  is believed to increase your chance of getting these rare genetic diseases diseases.  https://genetics.thetech.org/ask-a-geneticist/genetics-inbreeding

Not sure I followed your second paragraph.... (maybe because it's late and my genetics is very rusty)....

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Peggy, regardless, hemophilia is not caused by inbreeding and people should not be associating hemophilia with inbreeding, as that is not only inaccurate but potentially embarrassing to any number of people who have hemophilia or who carry the gene.

Because of the way the X chromosome is inherited, it does not matter how related or unrelated one's parents happen to be. Your parents could be from opposite sides of the globe and you could still get hemophilia if your mother happens to be a carrier of it or your father happens to be a hemophiliac.

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Jessica, however one can not deny that in this case the participants in these breedings did not have to travel the globe to find a mate with the defect.   So...inbreeding was indeed the cause of the defect.

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Jessica,

I totally agree that hemophilia isn't caused by inbreeding, it's a gene mutation.  I'm very familiar with x-chromosome mutations that cause disease.... my family line had an x-chromosome mutation, starting with my great grandmother, resulting in at least 7 deaths (all teenage males) from muscular dystrophy.  Fortunately, there's now DNA testing for the female carriers.  (Before 1980, the males with muscular dystrophy usually died before becoming a parent...)    No one has ever thought to suggest it was CAUSED by inbreeding.    

However,  inbreeding creates a lack of genetic diversity that makes hemophilia more common in the inbreed family lines with that gene mutation.

   

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Trudy, no it was not. Inbreeding did not cause the hemophilia. Queen Victoria's female-line descendants could have married anyone and they would still have passed down the faulty hemophilia gene on their X chromosome. Please do not spread misinformation. It is not difficult to educate yourself.

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Jessica.  Aside from the fact you are exceptionally rude telling me "  it is not hard to educate yourself"  the very clear fact is the women could very well have married someone else, but they DID NOT.  So since they did not marry outside the lines,

inbreeding did indeed cause the defects.    

I have bred genetically clean dogs for years.  A bred with a very limited gene pool.  In the 1970s less than 30 of them existed. I very easily could have bred my dogs to dogs with genetic faults or carriers, but I did not.  The dogs are by necessity inbred.  The choice is not to continue breeding defects.

The clean genetics on my dogs is a result of selective inbreeding.  The defects in the breed are also the result of inbreeding.  Poor choices of mates.  It is no different in humans.

But then this appears to be beyond your scope.

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Peggy,  it is possible that hemophilia in your family was not caused by inbreeding.  In the case of Queen Victorias descendants inbreeding was a factor.

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Queen Victoria is thought to have had a spontaneous mutation on one of her X chromosomes. The mutation meant that this gene did not 'work' to provide the factor needed to clot blood. The other non mutated X chromosome did 'work.' so Victoria herself did not have haemophilia.

Victoria's  male children did not receive an X chromosome from their father. Each one  therefore had a 50% chance of receiving the mutated gene from Victoria.  If they received the mutated gene their blood would not have the factor necessary to clot properly.  Only Leopold is known to have  been a haemophiliac . If he had children  (ne didn't so hypothetical) His son would  not have  inherited his  X chromosome. His  daughters would  and would have been carriers (like Victoria and some of his sisters); no matter who they married. (edited, as pointed out below he did have children)

Victoria's  daughters received one non mutated gene from Albert but had a 50% chance of receiving the mutated gene from Victoria. Once again, one non mutated gene is sufficient. If they received the mutation,  each  of their male children had a 50% risk of the disorder and each of their female children a 50% risk of being a carrier. 

The cousin marriage betwen Victoria and Albert was  totally irrelevant. descendant chart 

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Trudy, you call me rude, which is a personal attack and I do not appreciate it. You do not understand the genetics behind this hemophilia issue, and instead of acknowledging that, you double down on your ignorance.

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Hi Helen, you are correct in what you say except that Prince Leopold did have two children. His daughter Alice inherited his faulty hemophilia gene on the X chromosome and passed it down to her own son, Rupert. Perhaps it will help some folks to understand that Prince Leopold and his wife Helena were only distant cousins, being third cousins twice removed. Yet more proof hemophilia was not related to being inbred.

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Oops,  thank you Jessica. That was a silly mistake. I've crossed out the incorrect bit.

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Oh that is right! it is dominant not recessive - like polydactile (sp?) extra fingers and toes

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Jessica, since you chose to personally attack me in a public forum for no reason when you told me " it isn't hard to educate yourself" you insulted me. I did not appreciate it and the you compound your rudeness my telling me I have "  doubled down on my ignorance".  And I have no understanding of " the genetics behind the disease.  

First of all I happen to be in the unfortunate position of having more than one "familial"  blood disorder not to mention nasty neurological disorders.  Familial , as in passed down in families. While these things can happen in any match they are directly caused by inbreeding in the case of my ancestors.  Which is entirely the point you can not seem to gasp.

I am talking about defects being passed down because of the choice made to " breed" into close family with genetic defects. Sealing the faults into a blood line.  Causing familial defects.  So inbreeding as a choice was the cause of the defects.

Thus the social choices made to inbreed caused the defects. I really do not expect you to understand.  I am sure others will.

So while obviously you can not move out of your box from the genetic perspective to the social aspect and see the other perspective it does not mean I am uneducated or ignorant.

Answer 4

Inbreeding is not necessarily a reason for defects.  Bad inbreeding is the result of defects.  Breed fault to fault you get faults.  Breed lines clear of faults you don't get defects.

Comments

Not completely correct. Most common mutations are harmless if you only have one copy. In heavily inbreeding populations many genes double up, and this increases the dangers.

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I just noticed the discussion above. So yes, X chromosome mutations for men (like Y chromosome mutations for men and mitochondrial DNA mutations for anyone) don't work the same way as the doubling up explanation I gave.

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Hi Andrew. There's a few different ways that genetic diseases occur. Some are spontaneous mutations (called de novo) that might occur at conception. Some, like hemophilia, are X-linked diseases that are inherited in a special pattern. Some are inherited in an autosomal recessive pattern, like Tay-Sachs, where both parents may be carriers of a recessive gene, and their child happens to inherit both copies. The nastiest, in my opinion, are the diseases like Huntington's, which are carried on a dominant gene (therefore, a child only needs one copy to get the disease).