What are the genetics behind Klinefelter's syndrome?

Answer 1

Klinefelter Syndrome is not caused by genes but is rather caused by chromosomal nondisjunction, or an odd number of chromosomes. Klinefelter Syndrome is particularly the presence of more than one X chromosome in a male's karyotype in addition to one Y chromosome (normal males have one X and one Y). Typically, a Klinefelter patient will feature the XXY karyotype, although the presence of additional X chromosomes has been reported. The adverse phenotypes associated with Klinefelter Syndrome are due to complications arising from gene dosage, or the amount of gene expression, not due to the presence of a certain gene or mutation.

Answer 2

Klinefelter's syndrome results in an atypical arrangement of the sex chromosomes. Women are XX, men are XY but males born with Klinefelter's syndrome are XXY. This results in sterility in the individual as well as an inability to produce normal amounts of testosterone. There is varying degrees of reduced mental capacity and physical impairment. Treatment involves male hormone injections at puberty, lots of encouragement to maximise cognitive and physical ability and patient training of social skills.

Answer 3

Klinefelter's syndrome is when a man is born with an additional X chromosome. Therefore, he is XXY (instead of XY).

During the cell replication that took place in Meiosis (the splitting of cells for reproduction), nondisjunction occurred and one gamete received 22 chromosomes and another, 24. The normal chromosome count is 23 in gametes so it can create a person with 46 total chromosomes when the sex cells meet. In this case the gamete with 24 chromosomes met a normal gamete and made offspring with 47 total chromosomes.

Klinefelter's syndrome is not considered an inherited condition; one would be unable to pass it on. It's simply a mutation that occurs during cell replication.

Also it means:

Klinefelter syndrome, 47, XXY, or XXY syndrome is a condition in which human males have an extra X chromosome. While females have an XX chromosomal makeup, and males an XY, affected individuals have at least two X chromosomes and at least one Y chromosome.[1] Because of the extra chromosome, individuals with the condition are usually referred to as "XXY Males", or "47, XXY Males".[2]

This chromosome constitution (karyotype) exists in roughly between 1:500 to 1:1000 live male births[3][4] but many of these people may not show symptoms. The physical traits of the syndrome become more apparent after the onset of puberty, if at all. [5]

In humans, 47XXY is the most common sex chromosome aneuploidy in males[6] and the second most common condition caused by the presence of extra chromosomes. Other mammals also have the XXY syndrome, including mice.[7]

Principal effects include hypogonadism and reduced fertility. A variety of other physical and behavioural differences and problems are common, though severity varies and many XXY boys have few detectable symptoms. Not all XXY boys and men develop the symptoms of Klinefelter syndrome.

Answer 4

non-disjunction. Men with this syndrome have an extra X chromosome.

Answer 5

Klinefelter's syndrome only has one genotype, it is XXY.

Answer 6

47,XXY. This means that someone with Klinefelter's has 47 chromosomes, including 2 X chromosomes and a Y chromosome.

Answer 7

Men with Klinefelter's Syndrome have an extra X sex chromosome, so instead of being XY, they are XXY.