In 2005, Cheng reported that one amino acid difference in the gene SLC24A5 is a key contributor to the skin color difference between Europeans and West Africans.

“The mutation in SLC24A5 changes just one building block in the protein, and contributes about a third of the visually striking differences in skin tone between peoples of African and European ancestry,” says Cheng, professor of pathology.

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In this current part of the project, Victor Canfield, assistant professor of pharmacology, together with Cheng, studied DNA sequence differences across the globe. They studied segments of genetic code that have a mutation and are located closely on the same chromosome and are often inherited together. This specific mutation in SLC24A5, called A111T, is found in virtually everyone of European ancestry.

A111T is also found in populations in the Middle East and Indian subcontinent, but not in high numbers in Africans. Researchers found that all individuals from the Middle East, North Africa, East Africa, and South India who carry the A111T mutation share a common “fingerprint”—traces of the ancestral genetic code—in the corresponding chromosomal region, indicating that all existing instances of this mutation originate from the same person.

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NO TWO NOSES SMELL THE SAME

How you sense a smell—as pleasant or offensive—may be decided by a difference at the smallest level of DNA—one amino acid on one gene, researchers say.

There are about 400 genes coding for the receptors in our noses, and according to the 1000 Genomes Project, there are more than 900,000 variations of those genes. These receptors control the sensors that determine how we smell odors. A given odor will activate a suite of receptors in the nose, creating a specific signal for the brain.

But the receptors don’t work the same for all of us, says Hiroaki Matsunami, associate professor of molecular genetics and microbiology at the Duke University School of Medicine. In fact, when comparing the receptors in any two people, they should be about 30 percent different.

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While researchers had earlier identified the genes that encode for odor receptors, it has been a mystery how the receptors are activated. To determine what turns the receptors on, researchers cloned more than 500 receptors each from 20 people that had slight variations of only one or two amino acids and systematically exposed them to odor molecules that might excite the receptors.

By exposing each receptor to a very small concentration—1, 10, or 100 micromoles—of 73 odorants, such as vanillin or guaiacol, the group was able to identify 27 receptors that had a significant response to at least one odorant.

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Your face may have been sculpted by junk DNA

Even the prettiest faces are built using junk. In mice, the shapes of the face and skull are finely tuned by junk DNA, so called because it was initially thought to lack function since it doesn't encode proteins. The same junk DNA sequences are found in humans, so they are probably also shaping our faces.

This finding could help us make sense of some congenital conditions, such as cleft palates, that can develop even when the genes that shape the face appear to be working normally

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Genes Controlled with Light

Scientists have found a way to use light to control blood sugar in mice.
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Using a protein from the human retina, researchers in Switzerland have developed a method to control the expression of target genes with light. The scientists say the technology could be employed in the near term to boost the production of biological drugs, such as those for cancer, by enabling precise control over protein production. In the long term, cells engineered to carry the light-sensitive switch could be implanted into patients to produce a missing hormone, such as insulin, on demand.

In a Brazilian Town, a Rogue Gene and a Boom in Twins

I had heard many "outlandish theories" about this town and its twin population, as described further in the article...glad to see it is all in the genes!
uvealblues

SANTIAGO, Chile — For years, so many twins have been born in the small southern Brazilian town of Cândido Godói that residents wonder whether something mysterious lurks in the water, or even if Josef Mengele, the Nazi physician known as the Angel of Death, conducted experiments on the women there.
But a group of scientists now says it can rule out such long-rumored possibilities. Ursula Matte, a geneticist in Porto Alegre, Brazil, said a series of DNA tests conducted on about 30 families since 2009 found that a specific gene in the population of Cândido Godói appears more frequently in mothers of twins than in those without. The phenomenon is compounded by a high level of inbreeding among the population, which is composed almost entirely of German-speaking immigrants, she said.
“We analyzed six genes and found one gene that confirms, in this population, a predisposition to the birth of twins,” Dr. Matte said. 
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