Iceman’s Sardinian ties explained
When the genetic makeup of the 5,300-year-old mummy known as Ötzi was revealed earlier this year, scientists were surprised that his DNA suggests his modern-day relatives live in Sardinia instead of near the border of Austria and Italy where his frozen corpse was found. Analyses of DNA from present-day Europeans and remains of five other ancient people suggest that the Iceman wasn’t just a tourist from Sardinia. Instead he was probably part of a wave of migration of farmers into Europe, Martin Sikora of Stanford University reported November 8. Ötzi shares a more similar genetic makeup with a 5,000-year-old Swedish farmer and a 2,500-year-old Bulgarian than he does with hunter-gatherers from Sweden and the Iberian peninsula. The finding indicates that the spread of agriculture involved the people too, not just ideas, Sikora said.
DNA fingerprinting may point to innocent relatives
DNA testing has been used to pinpoint or rule out suspects in crimes. But a statistical test used to determine the solidity of a partial match between a crime scene sample and a genetic profile in a DNA database may be on shaky ground, Rori Rohlfs, a statistical geneticist at the University of California, Berkeley, reported November 8. The test, known as the Balding-Nichols model, underestimates how often coincidental matches might indicate a crime was committed by a relative of someone in the database when the actual perpetrator is unrelated. That is a problem because a few states, including California, allow law enforcement officials to investigate relatives of people in criminal databases if DNA fingerprints detect a partial match with a crime scene sample. Faulty statistics could lead to innocent people being investigated for crimes, Rohlfs said.
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Misregulated microRNAs may link obesity, breast cancer
An imbalance of small genetic molecules known as microRNAs may forge a link between obesity and cancer. Between 15 and 20 percent of cancers are attributed to obesity, said Cheryl Thompson of Case Western Reserve University in Cleveland on November 10. Thompson and her colleagues found that fat tissue from obese people over- or underproduce some microRNAs, small molecules that help regulate protein production. She speculated that disregulation of these microRNAs might disrupt communications between fat and other body tissues, leading to diseases including cancer. For example, a microRNA called miR-210 is misregulated in both obese people and breast cancer patients, suggesting that faulty control over the molecule may be one of the reasons for increased breast cancer risk among obese women, Thompson reported.
Genes link childhood growth and adult obesity
Genes that spark growth spurts in preschoolers are some of the same ones that predispose adults to obesity, a new study suggests. Early growth spurts in children are associated with a higher risk of heart disease in adulthood, but the reason for that was not known. To find possible genetic links, Marjo-Riitta Jarvelin of Imperial College London looked for genes associated with fast growth in more than 7,000 Finnish children and then repeated the experiment in more than 16,000 other children from around the world. Jarvelin reported November 9 that two genes are associated with how chubby babies are at 9 months old. One of genes, for the leptin receptor, is involved in appetite control. The other gene, PCSK1, encodes an enzyme that helps make insulin. Three genes associated with early growth spurts and higher body mass index at about age 5 are also linked to obesity in adults, Jarvelin reported.