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Can you make my blue eyes black?
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[QUOTE]Originally posted by Knowledgeiskey718: [QB] Indeed it is kinda weary to draw a conclusion on world populations for a single recent common ancestor for all blue eyed individuals. As soon as you asked I became curious. I think I will have to find a study in reference to Africans tested for blue eyes. As mentioned, the gene that causes the blue/brown have been identified as three different changes in the OCA2 gene that leads to blue eyes. In terms of eye color, OCA2 comes in two versions—brown (B) and blue (b). The brown version works in the stroma, while the blue version does not. Since the blue version doesn’t work there, no melanin builds up. So these individuals end up having blue eyes. The fact that genes associated with OCA2 are the cause of brown as well as blue eyes, I'd take it the gene is present in all humans as well. Being that Africa is the home of modern humans for over 150kya, there definitely could have been earlier cases in which this OCA2 version for brown eyes didn't work in the stroma of the eye. As we can see albinism certainly arose in Africa, albeit the non working version for brown eyes does not mean the person is an albino though. As we can see from the girl in the pic you posted. As per the article, here is the abstract and sampling methods. [QUOTE] http://www.springerlink.com/content/2045q6234h66p744/fulltext.html Abstract The human eye color is a quantitative trait displaying multifactorial inheritance. Several studies have shown that the OCA2 locus is the major contributor to the human eye color variation. By linkage analysis of a large Danish family, we finemapped the blue eye color locus to a 166 Kbp region within the HERC2 gene. By association analyses, we identified two SNPs within this region that were perfectly associated with the blue and brown eye colors: rs12913832 and rs1129038. Of these, rs12913832 is located 21.152 bp upstream from the OCA2 promoter in a highly conserved sequence in intron 86 of HERC2. The brown eye color allele of rs12913832 is highly conserved throughout a number of species. As shown by a Luciferase assays in cell cultures, the element significantly reduces the activity of the OCA2 promoter and electrophoretic mobility shift assays demonstrate that the two alleles bind different subsets of nuclear extracts. One single haplotype, represented by six polymorphic SNPs covering half of the 3′ end of the HERC2 gene, was found in 155 blue-eyed individuals from Denmark, and in 5 and 2 blue-eyed individuals from Turkey and Jordan, respectively. Hence, our data suggest a common founder mutation in an OCA2 inhibiting regulatory element as the cause of blue eye color in humans. In addition, an LOD score of Z = 4.21 between hair color and D14S72 was obtained in the large family, indicating that RABGGTA is a candidate gene for hair color. Material and methods [b] A three-generation Danish family (CFB#694) representing 28 informative meioses was used for linkage analysis and the blue eye color locus was finemapped. The family used in the linkage analysis, association and haplotype studies were of Danish origin and retrieved from the Copenhagen Family Bank, the families used in this study (families CFB#604-1505) (Eiberg et al. 1989). Only families with siblings, who had blue and brown eyes, respectively, were included in the study. The parents and siblings were classified as blue-eyed (Fig. 1a) or brown-eyed (Fig. 1c or d) individuals. Haplotypes were constructed from 100 Danish informative selected trios families, and most of these parents were also included in the association studies. These 100 triosis represented 45 families where at least one individual had brown eyes and 55 families where all individuals had blue eyes. Families where green and brown eye color spots segregate were not used. The haplotypes were deduced manually from the family study. Additional control material for DNA sequencing was collected from two large Danish families from the Copenhagen Family Bank. Five individuals from Turkey with blue eyes, black hair and light skin and two individual from Jordan with blue eyes, black hair and dark skin were included in the association analysis. Additionally, two persons with natal heterochromia were examined. The blue eye color phenotype was defined as a complete lack of brown pigmentation (Fig. 1a), an intermediate phenotype was defined as “blue eye with blown dots” (Fig. 1b), an intermediate brown eye color phenotype was defined as hazel with a broad peripupillary ring and was named the BEY1 phenotype (Fig. 1c), and a complete brown pigmented eye color was defined as the BEY2 phenotype (Fig. 1d). [/b] All individuals in the study were interviewed by questionnaires and asked to determine their own eye color from the categories: brown, blue, gray and green, and whether brown spots or brown peripupillar rings were present. Hair colors were categorized as red, black, brown and blond hair at the time when the persons were between 20 and 30 years of age. In family CFB#694, the eye color for all individuals was documented by photos and all key persons were re-examined. All individuals with green eye color or blue or gray eye color with brown spots not located close to the pupil were excluded from the linkage and association studies. Genomic DNA was extracted from the whole blood using standard phenol/chloroform procedures and the study adhered to the tenets of the declaration of Helsinki. [/QUOTE] [/QB][/QUOTE]
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