eye color

[Nick Theodorakis]

In article <2596fd39.251b1006 at aol.com>, GPJHSH at AOL.COM 
wrote:
>  heres the question: i am a girl, my father has blue  
> eyes , my mother  has 
> blue eyes and i have brown eyes. is this possible?

A search of the Online Mendelian Inheritance in Man (OMIM) 
at: http://www.ncbi.nlm.nih.gov/omim/ 
with the phrase "eye color" turns up this:

(*227240 EYE COLOR 1; EYCL1)

Eye color is likely to be a polygenic trait. The early view 
that blue is a simple recessive has been repeatedly shown to 
be wrong by observation of brown-eyed offspring of 2 blue-
eyed parents. My monozygotic twin brother and I, brown-eyed, 
had blue-eyed parents and blue-eyed sibs. Blue-eyed 
offspring from 2 brown-eyed parents is a more frequent 
finding. In some Norwegian families, Gedde-Dahl (1981) found 
diffusely brown eyes or centrally brown eyes segregating as 
simple dominant traits, symbolized BEY1. Possible linkage to 
Km (Inv) and to Co was found, suggesting the order Jk--Km--
BEY1--Co. (Co and Km are not measurably linked.) In a 
linkage study, Eiberg et al. (1986) scored eye color in a 
questionnaire as purely blue, green, gray, brown, or 'don't 
know.' The presence of brown areas or spots were also noted. 
For the purpose of linkage analysis, they assumed 2 main 
loci: (1) a 'green/blue' locus (GEY) with a dominant allele 
for green and a recessive allele for blue, and (2) a 'brown/
blue' locus (BEY) with a dominant allele for brown and a 
recessive for blue. Linkage of GEY with Lutheran and 
secretor (located on chromosome 19 at q13.1) was
found. They reported a lod score of 3.37 (theta = 0.0 for 
males and 0.07 for females) against Lutheran and of 1.79 (at
theta = 0.1 in males) against secretor, from observations 
largely in different families. In the full report, Eiberg 
and Mohr (1987) reported a combined lod score of 9.19 for 
linkage between GEY and the Lutheran-secretor systems. They 
also found evidence for linkage of GEY to brown hair color 
(113750) with a lod score of 5.06.  


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