Pedigree analysis of an X-linked recessive trait:
The Genetic Theory of History
A is an
recessive disease, characterized by improper
clotting of the blood due to a deficiency in Coagulation Factor VIII.
Hemophilia was introduced into the germ line of European
royal families by a "sporadic" mutation in Queen Victoria [circle
& dot, III-2],
who passed the allele on to three of her children. The
allele passed to the Russian royal family through Victoria's
and her son (Tsarevitch
Alexis [solid square, VI-12]
had it), as well as the Spanish royal family. King Juan Carlos [VII-14] did not inherit
it, though two of his uncles did.
Alexis' hemophilia is historically
significant. The concern of Tsar Nicholas II for the
Tsarevitch's health distracted him from difficulties facing
the Russian Empire before and during World War I, and
brought his wife under the influence of the monk, Rasputin.
The abdication of the Tsar
in 1917 was materially affected by his belief that the
Alexis would be unable to succeed him. The power vacuum
contributed to the onset of the Bolshevik Russian Revolution of
1917. The book and movie "Nicholas
are an historically accurate account.
Homework: in the pedigree
(1) Is it possible to exclude
the possibility that Queen Elizabeth II [VII-1] is a carrier for
(2) Neither Prince William
or Prince Harry (IX-1,2) have
hemophilia. Who is the first of their ancestors whose phenotype
excludes the possibility that they would inherit the
hemophilia allele? Explain.
(3) Queen Victoria
is said to carry a novel
sporadic mutation. Which individual in the above
pedigree indicates this?
(4) How many copies of Queen Victoria's mutated allele are
known to have existed? Does the novel allele from Queen
Victoria still exist?
(5) Grand Duchess
suggested to have escaped the
murder of the rest of her family in 1919. Speculate on
consequences of a heterozygous heir to the Russian throne in
the post-Soviet era.
Queen Victoria and her
extended family. She sits at centre, with her grandchildren in
Figure ©2002 by Griffiths et al;. all text material
©2011 by Steven M. Carr