Pedigree analysis of an X-linked recessive trait:
The Genetic Theory of History

    Hemophilia A is an inherited X-linked 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 granddaughter Tsarina Alexandra [V-8] 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 and Alexandra" are an historically accurate account.

    Homework: in the pedigree above,
(1) Is it possible to exclude the possibility that Queen Elizabeth II [VII-1] is a carrier for Hemophilia? Explain.
(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 Anastasia (VI-11) is periodically suggested to have escaped the murder of the rest of her family in 1919. Speculate on the 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 her lap.

Figure ©2002 by Griffiths et al;. all text material ©2011 by Steven M. Carr