The Y chromosome and genetics

[Soubrette]

I was watching the X-Men2 the other day and it was explained that the mutants received their psionic powers through the male line.

I know little about genetics and all the hereditary things I've heard of get passed through the female (ok the sum total of that is colour blindness, male pattern baldness and haemophilia). Is it possible for the male line to pass on an heritary trait and if it is - would this hereditary trait show up in females at all?

I've been left wondering

Sou

 

[Buddy]

I was watching the X-Men2 the other day and it was explained that the mutants received their psionic powers through the male line.

I know little about genetics and all the hereditary things I've heard of get passed through the female (ok the sum total of that is colour blindness, male pattern baldness and haemophilia). Is it possible for the male line to pass on an heritary trait and if it is - would this hereditary trait show up in females at all?

Sou

Yes, there can be hereditary traits attached to the Y chromosone, but I would postulate that the effects would likely be related to testosterone. And as the X chromosone would be passed from the father to a daughter, those mutations would not be passed to a daughter.

 

[arcticpenguin]

Some of the things you mention, e.g. male pattern baldness and hemophilia, are actually passed through the X chromosome. Since a male child has only one X chromosome in his cells, he will display the symptoms.

A female child will have a second X chromosome, one from each parent, so statistically is much less likely to display symptoms; she would have to have copies of the relevant gene on both of her X chromosome for any of these recessive traits to show up.


As Buddy mentions, it is also possible for traits to be passed through the Y chromosome from father to son.

 

[Soubrette]

Thanks guys

Could you give an example of a father to son hereditary trait? and am I understanding this right - such a trait would not affect female children?

Sou

 

[Buddy]

I did a quick search and found that hairy ears is a Y-linked trait

 

[arcticpenguin]

I did a quick search and found that hairy ears is a Y-linked trait

Thanks, dad.

 

[slimshady2357]

I may have missed something, but the relevant question about the movie hasn't been answered as far as I can tell.

In the movie it says the mutant gene is passed on through the father, yet it is seen in girls and boys....

How is this possible?

Shouldn't it be in boys only if it's on the Y chromosome? And shouldn't it be possible for the mother to pass it on as well, or at least be partly responsible, if it's on the X chromosome?

I'm still confused....

Adam

 

[Soubrette]

I may have missed something, but the relevant question about the movie hasn't been answered as far as I can tell.

In the movie it says the mutant gene is passed on through the father, yet it is seen in girls and boys....

How is this possible?

Shouldn't it be in boys only if it's on the Y chromosome? And shouldn't it be possible for the mother to pass it on as well, or at least be partly responsible, if it's on the X chromosome?

I'm still confused....

Adam

That's Hollywood science for you

I'm reading that it's not possible However I admit that as I instinctively thought that anyway - I may be reading these responses as merely a confirmation of my intuitive feelings (surely not )

Perhaps all female mutants are XXY individuals? Although the article I read about that some years ago and thus have only the sketchiest of memories seem to imply that these women would be malformed in some way and probably infertile - but as I say - sketchy details and most likely wrong.

The other theory is that the film was being somewhat economical with the scientific truth for some reason I can't quite understand - maybe a later plot device?

Sou

 

[Thanz]

I'm not a scientist, and I don't play one on TV, but I think there is a difference between passing something from the male line and passing something in the Y chromosome.

I have a daughter. I like to think that SOME of her genetic make-up comes from me (which would be the male line) but obviously not the Y chromosome. For example, she has blue eyes - just like her dad.

 

[Buddy]

I'm not a scientist, and I don't play one on TV, but I think there is a difference between passing something from the male line and passing something in the Y chromosome.

I have a daughter. I like to think that SOME of her genetic make-up comes from me (which would be the male line) but obviously not the Y chromosome. For example, she has blue eyes - just like her dad.

I am a scientist and I don't play one on TV.

Yes, there is a difference. You have passed on 23 chomosomes to your daughter, or half of your 46. Every chomosome is one of a matched pair. They are very similar but not identical (because one is from your father and one from your mother). The only chomosome pair with major difference is the X and Y.

So your daughter has 50% of your chomosomes and that inlcludes the X of your XY pair.

In a related topic, the majority of sex-linked traits are on the X chomosome (eg, color-blindness). So if I am color blind, I got it on the X chomosome from my mother (as my father gave me a Y). When I have a child I can pass my defective chomosome to a daughter, who will be a carrier (if she gets a non-mutated X from the mother) or will be color blind (if she also gets a defective X from her mother). If I have a son, he will get his X from his mother and only a Y (without the mutation) from me.

 

[Shane Costello]

Because the X chromosome is much larger than the Y chromosome, one X chromosome is shut down in female cells to save on energy. This raises some interesting scenarios, particularly when it comes to cloning. For instance CC the cloned cat has a different colour pattern to it's cloned cat, probably due to variable X-c'some inactivation. Tortoiseshell cats are always female, because their distinctive fur pattern is due to differential patterns of X chromosome inactivation

 

[Soubrette]

I'm not a scientist, and I don't play one on TV, but I think there is a difference between passing something from the male line and passing something in the Y chromosome.

I have a daughter. I like to think that SOME of her genetic make-up comes from me (which would be the male line) but obviously not the Y chromosome. For example, she has blue eyes - just like her dad.

Indeed you would have passed her an x chromosome - but where did that come from, from your mother surely?

I genuinely can't see where a male hereditary trait could be passed on as a trait unless it's linked to the Y chromosome.
Can someone explain this to me (in very simple terms) if this is not the case?

As an aside Thanz - and as I understand it, if your wife has brown eyes or dark eyes - the reason your child has blue eyes is because your wife has a recessive blue eyed gene (I don't think that's the right word but I can't remember the actual scientific term) which was passed to your daughter. If she had passed her dark eyed gene to your daughter then she would have dark eyes. So your daughter had blue eyes like her Dad in part thanks the the genetic hand dealt her by her Mom

Sou

 

[BillyJoe]

Everyone,

Is it possible for the male line to pass on an heritary trait.....

Yes, it is possible but I don't think it ever actually happens. There are rare mutations in the Y gene but they generally cause azoospermia (inability to produce sperm) and, of course, are not passed on.

.....would this hereditary trait show up in females at all?

No, because females are XX (they do not have a Y gene).

Some of the things you mention, e.g. male pattern baldness and hemophilia, are actually passed through the X chromosome.

Yes, Sou did, in fact, imply that they are X-linked traits.

In the movie it says the mutant gene is passed on through the father, yet it is seen in girls and boys....How is this possible?

It isn't.
If it is Y-linked it will be passed to all his sons and none of his daughters.
If it is X-linked it will be passed to all his daughters and none of his sons.

Perhaps all female mutants are XXY individuals? Although the article I read about that some years ago and thus have only the sketchiest of memories seem to imply that these women would be malformed in some way and probably infertile - but as I say - sketchy details and most likely wrong.

Sorry Sou, it is wrong.
XXY individuals are phenotypic males but you are correct about them being infertile - they are azoospermic.
The condition is called Klinefelter's Syndrome

.....I think there is a difference between passing something from the male line and passing something in the Y chromosome.

I suppose it depends on nomenclature but I think "passing along the male line" would mean: male -> male -> male etc. This could only occur through the Y chromosome.

You have passed on 23 chomosomes to your daughter, or half of your 46. Every chomosome is one of a matched pair. They are very similar but not identical (because one is from your father and one from your mother). The only chomosome pair with major difference is the X and Y.

So your daughter has 50% of your chomosomes and that inlcludes the X of your XY pair.

In a related topic, the majority of sex-linked traits are on the X chomosome (eg, color-blindness). So if I am color blind, I got it on the X chomosome from my mother (as my father gave me a Y). When I have a child I can pass my defective chomosome to a daughter, who will be a carrier (if she gets a non-mutated X from the mother) or will be color blind (if she also gets a defective X from her mother). If I have a son, he will get his X from his mother and only a Y (without the mutation) from me.

Because the X chromosome is much larger than the Y chromosome, one X chromosome is shut down in female cells to save on energy. This raises some interesting scenarios, particularly when it comes to cloning. For instance CC the cloned cat has a different colour pattern to it's cloned cat, probably due to variable X-c'some inactivation. Tortoiseshell cats are always female, because their distinctive fur pattern is due to differential patterns of X chromosome inactivation

Interesting isn't it - did you got that from hellcat's thread a month or so ago?

Indeed you [male] would have passed her [his daughter] an x chromosome - but where did that come from, from your mother surely?

Yes!
Mother XX -> Son XY -> Daughter XX

I genuinely can't see where a male hereditary trait could be passed on as a trait unless it's linked to the Y chromosome.

You are indeed correct, Sou.

As an aside Thanz - and as I understand it, if your wife has brown eyes or dark eyes - the reason your child has blue eyes is because your wife has a recessive blue eyed gene (I don't think that's the right word but I can't remember the actual scientific term) which was passed to your daughter. If she had passed her dark eyed gene to your daughter then she would have dark eyes. So your daughter had blue eyes like her Dad in part thanks the the genetic hand dealt her by her Mom

Excellent Sou, you know more than most.
blue blue + BROWN blue ->
1. blue BROWN (brown eyes)
2. blue blue (blue eyes)
3. blue BROWN (brown eyes)
4. blue blue (blue eyes)
If his wife didn't have the recessive gene for blue eyes, Thanz's daughter wouldn't have his blue eyes - but she didn't inherit them from him, she inherited them from both Thanz AND his wife.

regards,
BillyJoe.

 

[slimshady2357]

Re: Re: The Y chromosome and genetics

It isn't.
If it is Y-linked it will be passed to all his sons and none of his daughters.
If it is X-linked it will be passed to all his daughters and none of his sons.

Thanks, that's what I was getting from the lovely Sou But she seemed slightly unsure and I was hoping someone would come along and be so blunt as to just say "Yes, you're right Sou"

Which you did.

Adam

 

[bjornart]

Re: Re: The Y chromosome and genetics

Yes!
Mother XX -> Son XY -> Daughter XX

I was going to post something about gene swapping, and the realized it probably doesn't apply...

Correct me if I'm wrong, but isn't there quite a bit of gene swapping occuring in the production of sperm and eggs? So that if mother has chromosome pair ZZ, her eggs will have one Z chromosome which will mostly be like one of the ZZ pair, but will have several genes swapped with the other of the pair?

But the X and Y being different chromosomes and not a real pair messes that up I guess.

 

[BillyJoe]

bjornart,

First of all, that quote seems to have undergone a mutation.

You are nearly correct.
The X and Y chromosomes do undergo recombination but only at their tips.
Apparently at some point in their evolutionary history, a recombination supressor gene arose in the centre of the Y chromosome and its effect spread gradually to involve almost the whole chromosome except the very ends.
Thereby the X and Y chromosomes in males do not recombine.
In females, one of the X chromosomes becomes inactive forming what is known as a Barr Body.

(At least that is what I remember whilst reading around Hellcats thread on this subject)

BJ

 

[Earthborn]

Perhaps all female mutants are XXY individuals?

More likely they are just XY females. It's rare, but not impossible. Common enough to make the IOC finally discontinue its ridiculous gender verification.

Of course that doesn't explain why female mutants seem just as common as male ones. Of course I have no statistics from the Marvel universe to know for sure this is actually true.

Another possibility is that heridity in the Marvel Universe works completely different than in ours. One possible solution is to assume that humans in the Marvel universe descended from birds instead of mammals :

Bird sex determination is the reverse of that in humans; the female chromosome determines the sex of the bird. Male birds have two Z chromosomes, and are designated ZZ; females have one Z chromosome and one W chromosome (ZW).

From here

Of course then we have the obvious problem why there are so many male mutants... I give up, I can't make it make sense at all...

 

[bjornart]

bjornart,

First of all, that quote seems to have undergone a mutation.

You are nearly correct.
The X and Y chromosomes do undergo recombination but only at their tips.
Apparently at some point in their evolutionary history, a recombination supressor gene arose in the centre of the Y chromosome and its effect spread gradually to involve almost the whole chromosome except the very ends.
Thereby the X and Y chromosomes in males do not recombine.
In females, one of the X chromosomes becomes inactive forming what is known as a Barr Body.

(At least that is what I remember whilst reading around Hellcats thread on this subject)

BJ

It had to mutate to survive...

But, using cartoon science, couldn't the X-gene, not to be confused with the X-chromosome, be, in some way, detrimental to the egg, but not a sperm or the embryo. So it's not actually passed only to sons, but any female-unfertilized egg expressing the gene is non-viable.

 

[Aoidoi]

I don't remember the passed down from the male line being said in the movie. Do you recall the context?

 

[Soubrette]

I don't remember the passed down from the male line being said in the movie. Do you recall the context?

Hmmm it was definitely said by Dr Xavier and I have this vague memory of Storm and some other mutants being there but not being the ones spoken to.

Adam and I talked about it after the film....but other than that no, maybe he'll have a better memory.

Here are some links of others asking the same question I did though

here and here.

Sou