Tag Archive genes

blueeyesfeature

Scientists found something huge..

…..that all blue-eyed people have in common

Scientists working to uncover our DNA history.

You’ve probably wondered, why do we have the colour eyes we do? It comes down to our genes. And scientists are really starting to get to the bottom of it.

Produced By Matt Johnston. Research by Lauren Friedman. 

RABGGTA is a candidate gene for hair color.

Originally posted by businessinsider.com

New research shows that people with blue eyes have a single, common ancestor. A team at the University of Copenhagen have tracked down a genetic mutation which took place 6-10,000 years ago and is the cause of the eye colour of all blueeyed humans alive on the planet today.

Studies carried out by scientists from the Institute of Forensic Genetics at the University of Copenhagen have concluded that all blue-eyed people share a common ancestor, someone who lived 6,000 to 10,000 years ago near the area by the Black sea.

Researchers analyzed and compared the unique genetic make-up of the chromosomes in the iris from 155 blue-eyed individuals from diverse regions such as Denmark, Turkey and Jordan.

All of the subjects that participated in the study had the exact same genetic “mutations” in specific chromosomes of the eye with very little variation on the genes, indicating that the “mutation” responsible for blue-eyes first arose and spread relatively recently.

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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

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Search for Genes Causing Eye Disease

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retina cons and rods

retina cons and rods

Genes and Vision loss.  The retina is a thin, light-sensitive tissue at the back of the eye. It captures light and converts it into a chemical signal which travels to the brain, ultimately registering as vision. The retina is actually part of the central nervous system and is considered part of the brain. The ‘photoreceptors’ or light-sensitive nerve cells of the retina, are divided into the rod cells and the cone cells, reflecting their actual shapes.

There are about 120 million rod cells spread throughout the retina. These are responsible for black and white vision, and allow vision in low-light conditions. Then the six million cone cells are located in the centre of the retina, in an area called the macula, and are responsible for colour vision and detailed central vision.

A group of diseases collectively called inherited retinal degenerative disorders are caused by genetic defects which cause vision loss. This may result in total blindness. These disorders are caused by genetic changes or mutations and are inherited within families.

These genetic mutations result in different disorders. Gene defects affecting mainly the rod photoreceptors cause retinitis pigmentosa. As a result patients experience night blindness and loss of peripheral vision, causing a tunnel-like vision. Genetic mutations causing a primary loss of cone photoreceptors result in Stargardt disease or macular degeneration and cause a loss of central vision.

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