What are the beneficial and harmful effects of abnormal chromosome numbers on an individual?

Please help! And thank you!!What are the beneficial and harmful effects of abnormal chromosome numbers on an individual?
There are no particularly beneficial effects. The results of abnormal chromosome numbers range from early lethal effects in utero (before birth) to relatively normal development.





There are 23 pairs of chromosomes. 22 of them are called the autosomal chromosomes and they are numbered 1 through 22. Having three of any of them (a 'trisomy') except chromosome 21 will almost always cause the fetus to abort spontaneously (occasionally chromosome 13 or 18 trisomies will come to term). Trisomy of chromosome 21 is called Down syndrome and most people are familiar with that--it is relatively common. Trisomy 13 is called Patau Syndrome and Trisomy 18 is called Edward syndrome. They are much more severe than Down and the children rarely survive to advanced ages.





Having only one of any autosomal chromosome (a 'unisomy') will result in very severe deficiencies or failure to survive in all cases.





The last pair of chromosomes is a little different. These are the sex chromosomes, and they have letters instead of numbers--they are X and Y. Normally if you are XX, you are female; if you are XY, you are male.





It is possible to be XO--to carry only one X chromosome--and still survive. This is called Turner syndrome and it is associated with certain abnormalities including short stature, infertility and sometimes but not always reduced intelligence, along with certain physical characteristics. It is not possible to be YO--a child needs that X chromosome to survive.





However, trisomies of the sex chromosomes are generally not only survivable but not comparatively as important as the autosomal ones. XXX, XXY, and XYY are all possible. There are some typical characteristics of these genotypes, but they are generally compatible with both life and with generally normal development.





Having even more extra chromosomes is also possible--there are a few cases of quintuple X known--but these girls are very severely affected.





It is also possible for there to be a trisomy or even a tetrasomy of the entire genome (usually in these cases more than one sperm fertilizes the same egg). These cases are called 'triploidy' or 'tetraploidy' and are almost always lethal in utero or shortly after birth. Occasionally, someone will be found to have a triploid or tetraploid population of cells in some portion of the body without being affected overall. We're not sure why that happens.





Let me guess. More than you wanted to know? ;-)What are the beneficial and harmful effects of abnormal chromosome numbers on an individual?
First off, stay awake in biology. Second, Diseases usually. Such as lack of certain chromosomes can result in mental retardation.
Haven't known on benefits.


Harmful are many, some involve retardness, aggressiveness.
Nothing beneficial I can think of...





Harmful: mental illness.