Question 9 Not yet answered and Helen had one daughter and one son, neither of w

Question

Question 9 Not yet answered and Helen had one daughter and one son, neither of whom had hemophilia. His daughter, Alice (V-22), had three children, one unaffected Points out of 1.00 Queen Victoria had one son who had hemophilia, Leopold (IV-10). He married Helen whose family had no history of hemophilia. Leoplod daughter and two sons, one of whom had hemophilia. Flag question Albert ictoria VI Alexei 6 4 hemophilia age at death = carrier for hemophilia Elizabeth II VII Charles What is the genotype of Leopold? O x(H)X(H) What is the most probable genotype of Helen? O X(H)XH) What is the most probable genotype of Alice? O x(H)XIH)

Explanation / Answer

H- dominant - normal (does not cause hemophilia)
h- recessive - defective (causes hemophilia)

Based on the Pedigree analysis, Hemophilia is found to be a X-linked recessive condition. Because Queen victoria is a carrier which means she has one dominant gene which is normal and one recessive gene which causes hemophilia. If Hemophilia were a X-linked dominant condition, she would have been affected, but she remained a carrier.
Hence, her genotype should be X(H)X(h).

The son Leopold gets the X chromosome from the mother and the Y chromosome from the father. He is affected as he should have got the defective protein coding chromosome i.e., the recessive h containing X chromosome from Queen Victoria. Hence, his genotype would be X(h)Y.

Helen is from a family who has no history of hemophilia. So she will not contain the recessive h. Hence, her genotype would be X(H)X(H)

Based on the pedigree, Alice is found to be a carrier for Hemophilia which means she has one dominant and one recessive gene. Her daugher is not affected as she would have got both normal H containing X chromosomes from the father and mother. One of her son is affected as he would have got the recessive h containing X chromosome from the mother while the other son would have got the normal H containing X chromosome.
Hence, her genotype probably would be X(H)X(h)

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