Down Syndrome

[gene]

Ok, so Down's sydrome is because the chromosome can't divide properly.

 

Let's say, an old age man and a normal-aged woman mates. Would that increases the chances of get DOwn's because of the age of the men? The post mention only about the age of women affecting the chances of getting Down's, so what about male?

 

I'm not sure. Although the zygote is the result of the fertilistion of the sperm and the egg. And technically i assume that the zygote is made up mostly from the ova? I kind of confused here.

 

Maybe a hereditary disease could be albinoism?

[gene]

Ok, so Down's sydrome is because the chromosome can't divide properly.

 

Let's say, an old age man and a normal-aged woman mates. Would that increases the chances of get DOwn's because of the age of the men? The post mention only about the age of women affecting the chances of getting Down's, so what about male?

 

I'm not sure. Although the zygote is the result of the fertilistion of the sperm and the egg. And technically i assume that the zygote is made up mostly from the ova? I kind of confused here.

 

Maybe a hereditary disease could be albinoism?

[Auburngirl05]

There IS an allele for albinism, it's recessive, so the disease is expressed when a person inherits a recessive allele from each parent (usually the parents were each heterozygous and didn't realize they carried the gene). This is a classic case of an inherited disorder and shows the contrast between a "normal" inherited disease and a chromosomal malfunction like Down's.

Skye made a good point about inheriting factors that increase disjunction rates, I hadn't thought about that, although it doesn't qualify as inheriting the disease, I would see how it could raise the incidence...but it's a good point I hadn't thought of before.

And I don't know the answer about the elderly father, although men produce sperm throughout their lives, so an old man wouldn't necessarily have "old sperm", while a woman has already produced her lifetime supply of eggs by the time she's born.

[Auburngirl05]

There IS an allele for albinism, it's recessive, so the disease is expressed when a person inherits a recessive allele from each parent (usually the parents were each heterozygous and didn't realize they carried the gene). This is a classic case of an inherited disorder and shows the contrast between a "normal" inherited disease and a chromosomal malfunction like Down's.

Skye made a good point about inheriting factors that increase disjunction rates, I hadn't thought about that, although it doesn't qualify as inheriting the disease, I would see how it could raise the incidence...but it's a good point I hadn't thought of before.

And I don't know the answer about the elderly father, although men produce sperm throughout their lives, so an old man wouldn't necessarily have "old sperm", while a woman has already produced her lifetime supply of eggs by the time she's born.

[Radical Edward]

As several others in addition to me have stated, you can't inherit a nondisjunction, it's a "mechanical" error in DNA replication.

 

but you have to bear in mind now, that every call has an extra c21 in it, so when meiosis takes place, some will have 2 21s in them, and some will have 1 21 *assuming no more errors) so it is inheritable.

 

 

The Down's syndrome female has ovaries containing a reduced number of smaIl follicles, which have a greatly increased rate of atresia1. Twenty-six non mosaic trisomy 21 females, in 29 pregnancies, have produced 10 offspring with Down's syndrome, two spontaneously aborted fetuses whose status could not be evaluated, and 18 (including one monozygotic twin pair) chromosomally normal offspring. Of these; two are mentally retarded, four have other congenital malformations, and three were either spontaneously aborted or died of prematurity (table 1). Older published references describe a further seven women with nine offspring (table 2), although insufficient data are available to evaluate these.

 

http://www.trisomie21.de/fertility_trisomy21_1989.html

[Radical Edward]

As several others in addition to me have stated, you can't inherit a nondisjunction, it's a "mechanical" error in DNA replication.

 

but you have to bear in mind now, that every call has an extra c21 in it, so when meiosis takes place, some will have 2 21s in them, and some will have 1 21 *assuming no more errors) so it is inheritable.

 

 

The Down's syndrome female has ovaries containing a reduced number of smaIl follicles, which have a greatly increased rate of atresia1. Twenty-six non mosaic trisomy 21 females, in 29 pregnancies, have produced 10 offspring with Down's syndrome, two spontaneously aborted fetuses whose status could not be evaluated, and 18 (including one monozygotic twin pair) chromosomally normal offspring. Of these; two are mentally retarded, four have other congenital malformations, and three were either spontaneously aborted or died of prematurity (table 1). Older published references describe a further seven women with nine offspring (table 2), although insufficient data are available to evaluate these.

 

http://www.trisomie21.de/fertility_trisomy21_1989.html

[muad'dib]

you can if you have a downe's parent. they are not sterile.

 

 

Actually most people with Down's syndrome are sterile.

[muad'dib]

you can if you have a downe's parent. they are not sterile.

 

 

Actually most people with Down's syndrome are sterile.

[_13eoWuLF__]

No it is the age of the woman. However old men may have less sperm count.?? Low sperm count can never be a good thing =(.

[_13eoWuLF__]

No it is the age of the woman. However old men may have less sperm count.?? Low sperm count can never be a good thing =(.

[Radical Edward]

Actually most people with Down's syndrome are sterile.

 

I know, I forgot to add "all"

[Radical Edward]

Actually most people with Down's syndrome are sterile.

 

I know, I forgot to add "all"

[Auburngirl05]

No it is the age of the woman. However old men may have less sperm count.?? Low sperm count can never be a good thing =(.

Elderly men do have a low sperm count, which affects fertility but low fertility rate isn't related to the nondisjunction, the sperm that they DO have is constantly being produced/replenished, in contrast to the eggs a woman has had since birth.

 

I had always heard that people with Down's were sterile also, although I could be wrong. Some descriptions of the disorder mention reduced development of secondary sexual characteristics.

[Auburngirl05]

No it is the age of the woman. However old men may have less sperm count.?? Low sperm count can never be a good thing =(.

Elderly men do have a low sperm count, which affects fertility but low fertility rate isn't related to the nondisjunction, the sperm that they DO have is constantly being produced/replenished, in contrast to the eggs a woman has had since birth.

 

I had always heard that people with Down's were sterile also, although I could be wrong. Some descriptions of the disorder mention reduced development of secondary sexual characteristics.

[_13eoWuLF__]

How about the age of Tony Randell having his last child. Yuck that gives me the willies he was I think 78 when he had his last one.

[_13eoWuLF__]

How about the age of Tony Randell having his last child. Yuck that gives me the willies he was I think 78 when he had his last one.

[Auburngirl05]

Low sperm count reduces fertility but doesn't necessarily mean infertility.

 

And I definitely agree with you about the Tony Randall thing.

[Auburngirl05]

Low sperm count reduces fertility but doesn't necessarily mean infertility.

 

And I definitely agree with you about the Tony Randall thing.

[Radical Edward]

I had always heard that people with Down's were sterile also' date=' although I could be wrong. Some descriptions of the disorder mention reduced development of secondary sexual characteristics.[/quote']

 

Some are fertile, as pointed out above in that link I provided, since there were several examples of non chimeric DS females having children (a disturbing number of children fathered by their own fathers/uncles/brothers I might add - I think this totalled 7 out of 24). They are less fertile though, and I get the distinct impression that males are almost always infertile, except when chimeric. This is typical to examples seen elsewhere in nature, where male mules are pretty much always infertile, however hinnys (female mules) are occasionally fertile i.e. a male with a strange number of chromosomes is less likely to be fertile than a female with a strange number.

[Radical Edward]

I had always heard that people with Down's were sterile also' date=' although I could be wrong. Some descriptions of the disorder mention reduced development of secondary sexual characteristics.[/quote']

 

Some are fertile, as pointed out above in that link I provided, since there were several examples of non chimeric DS females having children (a disturbing number of children fathered by their own fathers/uncles/brothers I might add - I think this totalled 7 out of 24). They are less fertile though, and I get the distinct impression that males are almost always infertile, except when chimeric. This is typical to examples seen elsewhere in nature, where male mules are pretty much always infertile, however hinnys (female mules) are occasionally fertile i.e. a male with a strange number of chromosomes is less likely to be fertile than a female with a strange number.

[gene]

So the 2 'chromosome 21' can come from EITHER the male sperm, or female ova. Right?

 

Not entirely the old female fault, is it?

[gene]

So the 2 'chromosome 21' can come from EITHER the male sperm, or female ova. Right?

 

Not entirely the old female fault, is it?

[Radical Edward]

I see no reason in principle why it could not also be the fault of the male, however it does tend to be the fault of the female, and this is supported by obseravtion of increasing incidence of Down's with female age, and no linkage to male age.

[Radical Edward]

I see no reason in principle why it could not also be the fault of the male, however it does tend to be the fault of the female, and this is supported by obseravtion of increasing incidence of Down's with female age, and no linkage to male age.

[Auburngirl05]

This is typical to examples seen elsewhere in nature, where male mules are pretty much always infertile, however hinnys (female mules) are occasionally fertile i.e. a male with a strange number of chromosomes is less likely to be fertile than a female with a strange number.

I think there is a similar situation with the Liger/Tigon hybrids, one is supposedly more fertile although I can't remember which. Genetics is definitely fascinating.

 

It would be interesting to see a study that did investigate the father's age and effect on nondisjunction rates, for comparative data on the effect of aging mothers...and I agree, the stats on those DS women that indicate incest are definitely disturbing, my mother works at a sexual assault crisis center and the number of cases she sees as a result of mentally disabled people being taken advantage of is really disheartening...