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Archiver > DNA-NEWBIE > 2010-03 > 1268080653


From: "Nancy W." <>
Subject: Re: [DNA-NEWBIE] Color Blind
Date: Mon, 8 Mar 2010 12:37:33 -0800 (PST)
References: <56172.92341.qm@web83915.mail.sp1.yahoo.com><4b952b08.9298cc0a.108a.ffffdd55@mx.google.com>
In-Reply-To: <4b952b08.9298cc0a.108a.ffffdd55@mx.google.com>


Andy,
It doesn't look right to me either, but my genetics eduation is several decades old.  With color blindness (and probably most other recessive and dominant gene combinations) each child has a 50-50 chance of inheriting the trait. 

My father in law was one of ten children, six males.  Of those 6 males, 3 were color blind, three were not.  Three were short, three were tall (6'+).  Three became bald, three did not.  And just recently we have realized that three had/have alzheimers, three did not.  (Only one of the ten is still living.)

Thanks for pointing me to the article in Wikipedia. The inheritance article wasn't much help.  It did not deal with the unusual situation.

Nancy W. 




________________________________
From: Andy Micklethwaite

Hi Nancy

I can't confirm or deny the genetics but it doesn't look right to me. My mother was colour blind. Neither I nor my sister are. But one of her sons is. Colour blindness in women is rare but more common in men (about 10% in the UK from memory).

HTH Andy.

PS Just looked at Wiki http://en.wikipedia.org/wiki/Color_blindness
It has a section on the genetics

At 15:57 08/03/2010, you wrote:
>>From my high school biology class more than 50 years ago, I learned that the color blind trait is passed from the father to his daughters.  The daughters can carry the gene but the sons don't. 
>For a girl to be color blind, her father has to be color blind and her mother has to carry the gene.  That was the simple way I was taught.
>
>A situation in our family was just brought to my attention.  My father-in-law was color blind.  Both of my sisters-in-law carry the gene.  S-i-l A has two sons, one is color blind the other is not.
>S-i-l B has two sons, both are color blind.
>
>So far everything follows what I was taught several years ago.
>
>S-i-l B also has a daughter.  The daughter is not color blind, but her son is.  His father is NOT color blind.
>
>Is this unusual or can the mother pass the gene to the daughter?  If she can, I guess the daughter can have a son who is color blind. 
>
>I have not really studied this, but I listen closely when I hear anyone mention color blindness. 
>
>Nancy W. in Louisiana
>
>
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