It
is perhaps not surprising to hear that inbreeding is not the most
sensible concept. Dog breeders have known this for centuries.
Yet
for some odd reason the royal families of the world have not only felt
it necessary to breed with close family members but they have also done
so frequently.
The Russian royal
family is reasonably well known for its heritage of haemophilia. The
Hapsburg Jaw is less well known but is once again related to frequent
marriages between related individuals.
The
Hapsburg lineage has been a ruling house of Europe for some six
centuries. They primarily acted as rulers of Austria but relatives have
filled roles as Kings of Germany, Hungary, Croatia, Spain, Portugal,
Bohemia and Transylvania. There were also two Holy Roman Emperors,
namely Maximilian I and Charles V.
Generations of ruling notwithstanding, the Hapsburg Jaw is perhaps their largest claim to fame amongst the genetics community.
Mandibular
Prognathism is the technical term for a Hapsburg Jaw. It refers to a
tendency for the mandible, or the jaw to outgrown the upper jaw, thus
resulting in a large chin. Commonly it is known as an underbite. It can
be inherited as a part of a more severe syndrome (for example Crouzon’s
syndrome), or develop during life due to disorders such as
acromegaly. However in the vast majority of people it is inherited as a
dominant genetic disorder with variable penetrance.
Essentially
this means that if you inherit a copy of the gene from one parent, you
will develop a large jaw of some description depending how strongly that
copy of the gene is expressed (penetrates).
In
most cases mandibular prognathism is a relatively benign condition. On
occasion, however, it can cause problems with talking or chewing due to
an abnormal jaw alignment. Charles II of Spain, for example, was
apparently so disfigured that he was unable to chew.
As
you may imagine, there is also an industry thriving on cosmetic
alterations to the jaw. Mandibular Prognathism gives less scrupulous
cosmetic surgeons the ideal diagnosis to perform facial surgery.
(Arnold Schwarzneggar is someone famed to have had his corrected).
Now
I’m not suggesting that Jay Leno is a result of inbreeding. Nor am I suggesting he is related to royalty (although it is
certainly possible). However, as the following pictures demonstrate he
very clearly has something in common with them.
Take a look, and judge for yourself..
Charles II of Spain
Maximilian I, Holy Roman Emperor
(Public domain image - sourced from wikipedia)
Charles II of Spain
(Public Domain Image, sourced from wikipedia)
(Public Domain Image: sourced from wikipedia)
And Jay...
(1) Wikipedia (Online) Habsburg, Wikimedia Foundation Inc.
(last update: 6/4/07, accessed 10/4/07)
(2) OMIM (Online) Prognathism, Mandibular, NCBI
(last update: 18/3/2004, accessed 10/4/07)
Interesting.
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