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# Example punnet square for sex-linked recessive trait

Hemophilia, an X-linked recessive trait, affects blood clotting. A carrier woman and a hemophiliac man have a 50% chance of having a daughter with hemophilia. This is determined through a Punnett square, which shows the possible combinations of the parents' alleles. The Punnett square can also answer other questions, like the chance of having a hemophiliac son or a non-hemophiliac offspring. Created by Sal Khan.

## Want to join the conversation?

• Isn't there a 25% chance of there being a hemophiliac daughter because there are 4 offspring options... and only ONE of them is a hemophiliac girl?
• The question asks "What is the percent chance that SHE will have hemophilia", implying that the offspring will be a daughter, and out of the 4 offsprings only 2 are daughters. So since one daughter will be hemophiliac and the other won't, there is a 50% that the daughter will be hemophiliac.
• I am confused as why it is 50% instead of 25% because its 1/4 chance of daughter having it?
• It is 50% chance that a daughter has hemophilia because the question is what percent chance a daughter has it, so out of the two possible genotypes for a girl, one of them will be a carrier of hemophilia and the other will exhibit the disease, making it a 50% or 1/2 chance. Now draw a punnett square. If this hemophiliac daughter were to have children with a non hemophiliac man, all their daughters would be carriers and their sons would all have hemophilia. If she were to have children with a hemophiliac man, all their children would exhibit hemophilia. Hope this helps. :)
• If a female heterozygous recessive for hemophilia mates with a normal man and has 4 children, what are the possible genotypes and phenotypes expected in these offspring? *How many offspring do you expect to have hemophilia? **What sex of the offspring is affected?
• If the Father does not have hemophilia and the Mother is heterozygous for the disease there is a 25% chance that the offspring will have hemophilia, that offspring would be a boy because the girl needs two X chromosomes with hemophilia. Put it on a punnet square
• what would happen if the x chromosome is dominante
• In females, dominant X-linked mutations will always cause the disorder. This is because the mutated gene takes over or overrides the genes on the healthy X chromosome. In males, there's only 1 X chromosome and if it has the dominant mutation, they'll have the disorder.
• What is the mutation that causes hemophilia?
• Hemophilia is an X-linked recessive disorder that exists in two forms, hemophilia A and hemophilia B. Hemophilia A is characterized specifically by a mutation on the factor VIII gene of the X, whereas hemophilia B is caused by a mutation on the factor IX gene of the X chromosome.
• how do I know which is dominant or un dominant
• The small letter is the recessive, or un dominant trait and the dominant trait is the capital letter. In this case, the non hemophiliac allele, the H, is the dominant allele and the hemophiliac allele, the h, is the recessive allele. There are other diseases called X-linked dominant diseases, I'm sure you can find a video on it. Hope this helped. :)
• hemophilia is nas x-linked recessive trait that affects blood clotting. if a carrier woman and a hemophiliac man have a daughter, what is the percent chance that she will have hemophilia ?
• 50%. Out of the two possible daughter genes, one codes for hemophilia and the other codes for without. Therefore, the percent chance is 1/2 = 50%.
(1 vote)
• Hi
What would happen in the case that the X-linked trait is dominant?
Does that mean all of the offspring would display the dominant allele and none display the recessive allele?
Thanks :)