Scientists are beginning to uncover why redheads — and probably the non-gingers who carry a genetic variant common to redheads — may be so vulnerable to developing melanoma: For those who carry an allele, or gene variant, associated with red hair and freckles, cancer-causing genetic mutations occur at a rate 42 percent greater than they do for people who don't carry that gene variant. As a result, the average carrier of at least one problematic variant of the melanocortin 1 receptor, or MC1R, gene tends to develop cancer-promoting mutations at roughly the same rate as a person 21 years her senior.

Baby teeth contain clues about toxins

Baby teeth store a unique type of health record, with the potential to reveal everything that an individual has been exposed to, including environmental toxins such as lead and pesticides, and stress hormones produced by the baby in utero. Manish Arora, an environmental epidemiologist and exposure biologist at the Icahn School of Medicine at Mount Sinai in New York, explains that teeth form rings as they grow — just as trees do, but daily instead of annually — and each ring contains information about exposures that occurred on the day it was formed. Using specialized equipment, he has developed ways to analyze what's contained in those rings. "I often describe [teeth]," he said, "as biologic hard drives." Arora's work is part of an emerging field of study focused on the exposome, which refers to the totality of health-affecting exposures that a person experiences.

Gut bacteria differs with chronic fatigue

A study has identified a bacterial blueprint for chronic fatigue syndrome, offering further evidence that it is a physical disease with biological causes and not a psychological condition. There is no test to confirm a diagnosis of chronic fatigue syndrome, which causes extreme fatigue, In a study published in Microbiome, researchers recruited 48 people with CFS and 39 healthy controls. They found that people with CFS had significantly lower diversity of bacteria species and that had higher blood levels of lipopolysaccharides. Using these criteria, the researchers were able to identify more than 83 percent of CFS cases. "There's a biological difference between people with CFS and healthy people," said the senior author of the study, Maureen R. Hanson, a professor of molecular biology at Cornell.

Mother's flu shot briefly protects baby

Fetuses are temporarily protected by their mothers' flu shot, but that immunity fades within weeks after birth. A study paid for by the Gates Foundation and published online in JAMA Pediatrics, said the vaccine was about 86 percent effective until the babies were 8 weeks old. But by 24 weeks, it became statistically insignificant.

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