4. In 1995, a sixty-three-year-old man named Eugene Romanov, a resident of the f
ID: 188521 • Letter: 4
Question
4. In 1995, a sixty-three-year-old man named Eugene Romanov, a resident of the former Soviet Union, turned up. He shared both the disease and his last name with the royal family of czarist Russia. He proclaimed himself a grandson of Nikolas II's youngest daughter, Anastasia, whose body had at that time not been recovered, and who was believed by some to have managed to survive the revolution. Eugene Romanov claimed Anastasia was raised by a farmer, and later she married a nephew of her adopted parents and had a daughter, Eugene's mother Questions (a) According to Eugene's argument, what was the likely hemophilic status of Eugene's mother and grandmother? What about his father and grandfather? Is this argument plausible b) How plausible is it that Eugene inherited both hemophilia and the last name from the royal family? (Hint: Look how each of them is passed from generation to generation.)Explanation / Answer
The hemophilic background of the Romanov dynasty can be traced back to Nikolas II's wife , who was the daughter of Queen Victoria. Descendants of Queen Vicotria were either hemophilic males or carrier females. Since hemophilia is a X-linked recessive disorder and human males have XY chromosomes pair, hemophilia is more common in males where only one copy of altered gene on the X chromosome is sufficient to cause the condition (XHY). While females express this condition only when homozygous recessive for XHXH and become carriers when XXH. Therefore if Eugene is hemophilic, he has XHY chromosome pair.
Since Nikolas was normal and Nikolas's wife was carrier, then the chances of Anastasia inheriting XH chromosome from her mother will be
Nikolas
Nikolas's wife
Anastasia therefore had 50% chance of being carrier or 50% of being normal. So if Anastasia is a carrier, and Eugene's mother is not reported to be hemophilic, then Anastasia's husband (nephew) was normal. If Eugene's mother was hemophilic, then she would have inherited the XH chromosome from Anastasia and the only XH chromosome from Anastasia's husband.
Nephew (Anastasia's husband)
Anastasia (carrier)
Then Eugene's mother is a carrier (XXH) and male child inherits X chromosome only from his mother. So the hemophilic status of Eugene's father is not important.
Eugene's father
Eugene's mother (carrier)
Answer to 4(a).
Eugene's mother and grandmother were both carriers. Grandfather or Anastasia's husband was normal (non-hemophilic). Eugene's father can be either normal or hemophilic and it does not matter, as there is maternal inheritance of X chromosome in the male child.So Eugene will inherit XH chromosome from Anastasia's daughter, who was a carrier
On these grounds, the argument is plausible.
Answer to 4(b).
The other plausible argument is explained below. Anastasia can be normal (XX) and may not have inherited the XH chromosome from her mother (Nikolas's wife, XXH).
If the nephew was hemophilic which is not reported, then the following cross is also possible.
Anastasia's husband (nephew)
Anastasia (normal)
All female children will be carrier and all male children will be normal. SO Eugene's mother, Anastasia's daughter has 100% chances of being a carrier. SO again considering maternal inheritance of X chromosome in Eugene,then Eugene's fathers hemophilic background is not essential.
Eugene's father
Eugene's mother (carrier)
So Eugene can be hemophilic as well if he inherits the XH gene from his hemophilic grandfather.
So this can be a case where he does not inherit hemophilia from the royal family, but he inherits the X chromosome from the female descendants fo the royal family. So hecan still share the last name of the Romanov dynasty.
Nikolas
Nikolas's wife
X Y X XX (50% normal) XY (50%) XH XXH (50% carrier) XHY (50%)Related Questions
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