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| quote: | Originally posted by Ygrene
Here are the basics of it:
Male Pattern Baldness is hereditary, you get it from your mother! The explaination is genetic and linked to your mother's X-Chromosome. There is also an explaination of how your mother got the gene! There is currently a popular commercial on television talking about a hair loss prevention product that is “stronger than heredity”. The commercial has a young man who talks about his father, who like most men in his family, was bald by 30. The commercial is both right and wrong, Male Pattern Baldness is hereditary and you get it from your mother!
The explanation is that the genetic reason for Pattern Baldness is linked to your mother's X-Chromosome. Everyone get one-half of their genetic make-up from their mother and their father. The final chromosome pair of the 23 pairs is the sex determining set. While males are XY and females are XX the determination of an individuals sex is made by the father. It is the father who gives either the X chromosome, which matches with the woman’s X resulting in XX and a female child or the Y chromosome which joins with the woman’s X resulting in an XY match and a male child. It is the X chromosome or female sex chromosome that contains the gene for Male Pattern Baldness.
Since men have only one X chromosome, the gene for baldness is a single expression gene that shows up because there is no possible dominant gene to suppress what would normally be a recessive or hidden characteristic. Since Male Pattern Baldness gene is only on the X chromosome and men can only get that chromosome from their mothers, it is simple to see how this type of baldness is passed from mother to son.
The fact that it seems that men in families often have many generations of bald men tend to make this explanation of hard to believe, yet genetics explain it. Male Pattern Baldness is a condition that as previously stated is on a gene on the X chromosome. Since this form of baldness is recessive, it will be hidden if only one of the dominant genes is present. Since women have the XX chromosome pair, baldness will not occur unless both chromosomes have the recessive gene that causes baldness. A woman could have one of three genetic conditions:
Both X chromosomes with normal gene represented by Xn Xn this would appear as normal. One normal and one baldness gene on the X chromosome pair represented by Xn Xb, this would appear as normal. Both X chromosomes with the baldness gene represented by Xb Xb, this would appear as a woman with pattern baldness
Given these three female genetic possibilities there are 4 possibilities for male offspring:
1 for the first woman - 1 normal male XnY
2 for the second woman – 1 normal/ 1 bald male XnY / XbY
1 for the third woman – 1 bald male XbY
Once a male is born with the baldness gene he automatically passes it on to all his female offspring. If his mate is normal with the gene for baldness (Xn Xb) each female child born has a 50-50 chance of being born with male pattern baldness. This is because bald men can only give the Xb gene. This causes bald men to pass the gene and deplete the stock of Xn Xn females. This is how the women are able to keep producing males with pattern baldness. In total population about 30% of all females are Pattern Bald.
Below is a set of charts that illustrate the pattern.
Key Xn = normal Xb = Pattern Bald
XX = female XY = male
Normal Male Normal Female
Xn Xn
Xn Xn Xn Xn Xn
Y XnY XnY
Results All Normal
Normal Male Female recessive
Xn Xb
Xn Xn Xn Xn Xb
Y XnY XbY
Results: 2 normal females (one with trait for baldness) 1 normal male – 1 bald male
Bald Male Female recessive
Xn Xb
Xb Xn Xb Xb Xb
Y XnY XbY
Results: 1 normal females(with trait for baldness) – 1 bald female – 1 normal male - 1 bald male
Bald Male Bald Female
Xb Xb
Xb Xb Xb Xb Xb
Y XbY XbY
Results: All Bald |
OWNED!!!
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