Page 22 - Know your genome_English

Hemophilia: the royal disease Victoria,
Queen of England

-O

Royal descendants Royal descendants of Royal descendants
of England Prussia of Russia, Royal descendants of Spain
executed during the
Russian revolution
In the summer of 1818, the future Queen Victoria ot England was born. Her genome had a mutation for hemophilia,
carried on
theX chromosome. Victoria passed the gene on to some of her children and grandchildren, including many royal families of
Europe. In 1904, the long awaited Tsarevich, Grand Duke of Russia- Alexis Nicolaievich was born. From his mother, he

inherited an X chromosome
a
carrying copy of the mutant gene for hemophilia. Will he suffer from the diseasel?
Here is a partof the familytree of the royal families of Europe. A square refers to a male member and a circle refers to a female

member. Filled squares mean that this male member sufered from
hemophilia. Many of the female members, shown with half
filled circles, were carriers of the disease, bearing the mutation in one copy of the gene but not in the other. Why do male

members suffer from the disease whereas females even when
they carry one copy of the mutation survive and pass on the
mutant gene to their sons?

gene on a peculiarchromosome, called the X chromosome.
Here is a clue: the mutation is in a