As human beings, we normally should have 46 chromosomes, consisting of two pairs of 23 chromosomes, that are attached by proteins in a helix structure. You can see this as two spirals going in opposite direction being entangled. One pair you get from your mother and another from your father. Normally you should have all genes double, but not necessarily identical.
And for men one set of chromosomes is not identical either. There is a set that defines the sex of a person and these are the gender related chromosomes and some malfunctions can be due to a problem there. Normally a woman has two X chromosomes, while a men as and X and a Y.
During conception many things can go wrong. Normally during a meiosis or a split of the DNA, when the two strings are separated to unite with those of a different individual, some errors might occur.
Sometimes strings of DNA do not split as they should and you might get a third of a kind or a missing one. In many cases this might lead to premature death, due to a fetus not being vital.
Sometimes a chromosome defect is not gender related, like a triple 21st chromosome, that is the cause of the well known Down Syndrome.
Still there are exceptions of disorders that are gender related.
This is not really a chromosome disorder, but the lack of one gene: the one that makes the blood clot when you wound yourself. When you cut your finger, the bleeding will stop and your body will form a crust on the wound. Hemophilia patients do not have this ability and will not stop bleeding. Any injury might cause them to bleed to death.
This should not be really gender related, but so far it is most likely to strike men, because the gene responsible for this blood clotting, is on the X chromosome. Now sometimes this gene is not there. For a woman this is not a problem, because she has another X chromosome and the gene is most likely on there. You only need one of them, otherwise all men would be hemophilic.
But women who have a malfunctioned X chromosome might pass it to their children. There is a 50% change to it.
Now if the child is girl, there is no problem, since she might also get a normal X chromosome from her father, unless he is hemophilic. Only in that case a girl can have this illness. It is only recent that hemophilic men live long enough to reproduce. In the past they would not have had the chance to have daughters. And when they do, they still need the misfortune of having a wife that also carries the malfunctioned gene.
- Klinefelter Syndrome
This disorder is called after doctor Harry Klinefelter who first published a rapport on it in 1942.
It is a gender chromosome disorder by which men have at least one X chromosome too many in their cells. There are several variations, since it include all men that might have a simple XXY variant up to a four X variant. This means they have more chromosomes than a normal person, at least one, but sometimes even four. Life expectancy for all those is normal.
The symptoms are the same for all varieties and it occurs on 1 to 500 up to 1000 births of males.
The most common symptoms are:
- infertility: some men do not even produce sperms
- breast formation
- reduced facial or other gender related hair growth
- small testicles
- less muscular
Also are they often dyslectic. Men with just XXY usually have a normal intelligence, but those with more X's might be less intelligent.
This disorder does also occur among other species and is not only reported among human beings. A good example that cats can have it, is that a tortoise or spotted pattern on cats is gender related and can usually only occur on pussy cats.
But on rare occasions tom cats with a tortoise look show up and when tested, they turn out to be Klinefelters.
The variant XXYY does exist as well. This is not considered Klinefelter and is still awaiting a name.
- Turner Syndrome
This disorder occurs on 1 on 2500 females and this is due to the fact that they lack one X chromosome, so women with this disorder might have a X0 code.
Male fetuses that lack an X chromosome, or have just a Y, do not survive, so an X chromosome seems to be vital in to whether a fetus is due to live or not, as you can also make up from the Klinefelter syndrome, you can live with too many, but not with none.
Many girls with this disorder are infertile, but in some cases they do produce egg cells and might reproduce. Still there is a big change they miscarriage. When they can get pregnant, it is mostly the mosaic variant, which means that not all cells are lacking the missing X chromosome.
Some of the symptoms are:
- shorter than average: usually they do not grow taller than 5 foot, but they are quite heavy.
- short neck
- swollen hands and feet
- broad chest and not much developed breast and widely spaced nipples
- eye and ear trouble
- no spontaneous puberty
- higher risk of cardiac and kidney malfunctions
- thyroid malfunctions
Most of them have an average intelligence, but have trouble in learning because they do not concentrate well. They also might have trouble in evaluating time and space.
There is no real cure for the disorder, but today girls are given hormone treatments to reduce to problems and they have a normal life expectancy.
This disorder is also not typically human and is also investigated by mice and horses.
- Triple X-Syndrome
This disorder only effects women and those women have three X chromosomes. About 50% of these women are also so called mosaics, meaning that this X too much is not in all their genes.
In Denmark it is reported to occur in 1 on 1000 female births and the life expectancy is normal.
The symptoms are:
- low birth weight
- taller than average
- low BMI
- normal intelligence, still a learning problem might occur
- slightly delay in development of motoric skills, emotional development and speech
- long legs
Keeping that in mind, you may state that many of those triple X girls might end up on the cat walk and that their appearance might be opposite of the Turner woman.
At an early age they might encounter some trouble, they can be shy due to speech disorder, but they usually grow out of this all, so on average they have less health problems than women with the Turner Syndrome.
- XYY Syndrome
This effects only men and like the triple-X syndrome this also might only give some trouble at an early age, but many men with this disorder will grow up quite normal.
The symptoms are about the same as for triple X women and XYY men are on average normal and fertile. Many men who suffer this disorder might not even know it themselves.