x-linked diseases

Started by marsalien
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marsalien

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Both haemophilia and colour blindness are se-linked recessive but chances for haemophilia to occur are less as compared to that for colour-blindness.why?😕
 
Both haemophilia and colour blindness are se-linked recessive but chances for haemophilia to occur are less as compared to that for colour-blindness.why?😕

I don't understand the significance of this question. These two different sex linked recessive diseases are independent of each other, are they not? as are a whole host of other sex-linked recessive diseases. They all aren't expected to have to same occurence. Different diseases are attributed to different genes arranged differently on chromosomes so they will not have the same occurence.
 
lets say a man has a dominant sex-linked disease on the X chromosome.
he mates with a female with no gene of said disease.

the probability of any of their children having the disease are 50% ...right?
and the probability of a boy having the disease is 0%
the probability of a girl having the disease having the disease is 100%

does that follow the rules of mendel?
 
lol...i guess making a punnet square could simplify things.
im just trying to get to the point where i can "think about it" and then magically come up with the answer...kinda like using nifty shortcuts in math i guess.

okay here is another one:

a man has a sex linked disease.
a female also has it.
what (if anything) can you imply about its dominance/recessiveness?
which chromosome is it on?
if they mated and had offspring, what percentage of boys would inherit the disease? what percentage of girls would inherit the disease?
 
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lol...i guess making a punnet square could simplify things.
im just trying to get to the point where i can "think about it" and then magically come up with the answer...kinda like using nifty shortcuts in math i guess.

okay here is another one:

a man has a sex linked disease.
a female also has it.
what (if anything) can you imply about its dominance/recessiveness?
which chromosome is it on?
if they mated and had offspring, what percentage of boys would inherit the disease? what percentage of girls would inherit the disease?

Little tricks aren't necessary. It isn't hard. Work it out.

Just remember that fathers give X chromosome only to their daughters, and mothers give X chromosome to both sons and daughters.
 
lol...i guess making a punnet square could simplify things.
im just trying to get to the point where i can "think about it" and then magically come up with the answer...kinda like using nifty shortcuts in math i guess.

okay here is another one:

a man has a sex linked disease.
a female also has it.
what (if anything) can you imply about its dominance/recessiveness?
which chromosome is it on?
if they mated and had offspring, what percentage of boys would inherit the disease? what percentage of girls would inherit the disease?

The female could be a carrier for a dominant disease and express it or she could be homozygous recessive and express it if the disease was recessive. Without knowing her genotype, I don't think you could determine % risk of offspring getting the disease. I think the only way to know for sure is if you had an actual pedigree.
 
The female could be a carrier for a dominant disease and express it or she could be homozygous recessive and express it if the disease was recessive. Without knowing her genotype, I don't think you could determine % risk of offspring getting the disease. I think the only way to know for sure is if you had an actual pedigree.

1. You can't be a carrier for a dominant disease, only a recessive one.
2. It is possible to determine risk to potential offspring. In the practice of medicine, it is called genetic counseling.
 
lol...i guess making a punnet square could simplify things.
im just trying to get to the point where i can "think about it" and then magically come up with the answer...kinda like using nifty shortcuts in math i guess.

okay here is another one:

a man has a sex linked disease.
a female also has it.
what (if anything) can you imply about its dominance/recessiveness?
which chromosome is it on?
if they mated and had offspring, what percentage of boys would inherit the disease? what percentage of girls would inherit the disease?
This might help you.
http://forums.studentdoctor.net/showpost.php?p=5216436&postcount=2
 
lets say a man has a dominant sex-linked disease on the X chromosome.
he mates with a female with no gene of said disease.

the probability of any of their children having the disease are 50% ...right?
and the probability of a boy having the disease is 0%
the probability of a girl having the disease having the disease is 100%

does that follow the rules of mendel?

Be careful. Everyone has the same gene, its Alleles that are dominate or recessive, My Genetics prof asked tricky questions like that. So its more correct to day he has the dominate allele and she has recessive.
 
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