Monday, April 6, 2015

Inheritance of Eye Color

 More than one gene codes for eye color. It is uncommon, but it is now known that parents with blue eyes can have a child with brown eyes. Two separate genes OCA2 and HERC2 can lead to the inheritance of blue eyes. You need both genes to get a pigmented (brown) eye. Both of the genes work together, so it is possible to be a carrier of a dominant trait for brown eyes. So if both parents have blue eyes, but they are carriers for brown eyes, then the child can have brown eyes. Both genes are needed to work in order to have blue eyes (epistasis). Brown eyes are pigmented and blue eyes are not. OCA2 is one of the key genes in determining how much pigment is made, so this gene clearly plays an important role in blue eye color. A lot of pigment gives brown eyes, some gives green eyes, and none gives blue eyes. The HERC2 gene determines if the OCA2 is turned on. So both of these genes play key roles.
It is very interesting that more than one gene codes for eye color. It makes it even more interesting that hazel eyes are possible. The more of inheritance for eye color or more advanced that people used to think.

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4 comments:

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  2. Very interesting! I did not know it was possible for two blue-eyed parents to have a brown-eyed child. I always thought that two blue-eyed parents could only have blue-eyed children since the allele for blue eyes is recessive. I didn't know that more genes controlling the inheritance of the pigment in our eyes existed.

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  3. So crazy! I never knew that two blue eyed parents could have a brown eyed offspring either! I always, however, assumed there was more than one gene for eye color, considering the range of pigmentation there is in different eyes (brown, hazel, black, blue, green, etc).

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  4. It's amazing how we can go through years of learning that blue eyed parents can only have blue eyed children because it is a recessive trait. I think the identification of multiple genes coding for eye color fills a hole that has been left in the study of genetics. Like Christina said, there is such a wide range of pigmentation found in eye color, that it makes more sense now that this information was discovered.

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