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Genetic Linkage

Identical Twins, Physical Fitness, and Transgender Identity in the News

The terrific new documentary "Three Identical Strangers" tells the remarkable tale of triplets separated in infancy who met for the first time at age 19, in 1980. Their matching faces, mannerisms, behaviors, and quirks reverberate throughout the film, astonishing because the triplets were raised in economically diverse families. The film pays less attention to what makes them different.

Identical Twins That Differ Markedly in Physical Fitness

Another intriguing case of nature vs nurture in identicals is published in the new issue of The European Journal of Applied Physiology. Katherine Bathgate, James R. Bagley, and Andrew J. Galpin and their colleagues, from a trio of California colleges, compared 52-year-old identical twins who differ greatly in their physical fitness level. “TT” is a runner and triathlete, “UT” a sedentary truck driver. Because they share all their genes, differences in physical fitness reflect what the twins do and have done, not what they inherited.

To continue reading go to DNA Science, where this post first appeared. Read More 
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Natural Blood Doping and Rewriting the Textbooks

The phrase “rewriting the textbooks” is more than a cliché to me, because that’s what I do. I revise each of my books every three years, updating the science.

I love to explain biology through cases and stories, and am disturbed when something changes – that is, when new evidence indicates that facts aren’t as they seemed.

Sometimes it’s hard for me to give up favorite stories. Worst was the case of Phineas Gage.

Phineas Gage

I used Gage’s strange tale to open a nervous system chapter in a few editions of Hole’s Human Anatomy and Physiology, up until 2010.

To continue reading go to DNA Science, where this post first appeared.

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Alternate Facts: Why Are We Still Telling Women That Abortion Causes Breast Cancer?

On June 26th, the Supreme Court ruled in favor of crisis pregnancy centers that were challenging a California law, the Reproductive Fact Act, requiring clinic personnel to inform women of all family planning options — including abortion. The 5-to-4 vote put First Amendment rights of workers whose religion is against abortion above the rights of pregnant women to be told that California provides free or inexpensive family planning information, including abortion.

While critical information about abortion is omitted at many of the crisis pregnancy centers, misinformation is apparently readily dispensed. One popular mantra is that abortion causes breast cancer. It’s a claim likely to scare the daylights out of young, vulnerable women seeking help. But a deep-dive into studies published in the top medical journals shows it is untrue — but findings of those investigations tend not to be shared.

To continue reading go to Genetic Literacy Project, where this post first appeared. Read More 
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Telomere Testing: Science or Snake Oil?

It seems lately that any biometric can inspire a test pitched to consumers, using jargony buzzwords and promises of health, wellness, and longevity. Measuring the length of telomeres, the short DNA sequences at the tips of chromosomes that whittle down as we age, is one such pseudoscience-based offering.

“The DNA test to help you stay younger longer,” and “control how well you’re aging based on your telomere length,” blares one website. Send in a swab and receive “your current telomere length reported as the age of your cells in TeloYears, and the option to work with an expert to develop a personalized lifestyle improvement plan based on telomere science.”

Not surprisingly, Telomere Support supplements are available to help achieve the promised stoppage of time. These include the usual suspects of vitamins and anti-oxidants, plus black tea extract and pygeum extract (from the African cherry tree, used to treat an enlarged prostate). Only $59 a month!

Another company offers to tell the consumer “physiological/biological age” via the mean length of the telomeres, with a deal to test four times a year for $299, to track changes.

I’m not buying any of it.

Yes, diseases can result from abnormal telomere maintenance, but that’s got nothing to do with what the companies are pitching. Two new articles in the Mayo Clinic Proceedings report on 17 patients with short telomere syndromes, while a third article, a commentary, tackles the commercialization of the science, "Telomeres in the Clinic, Not on TV".

Continue reading at DNA Science, my blog for Public Library of Science.  Read More 
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Hybrid White Rhino Embryos: Genetic Rescue, Part 2

Two weeks ago, DNA Science covered the plight of the northern white rhino, suggesting assisted reproductive technologies (ARTs) that might preserve the genomes of the nearly-extinct subspecies. A paper published last week, in Nature Communications, reports creating embryos by injecting northern white rhino sperm nuclei into southern white rhino oocytes (unfertilized eggs).

The hybrid rhino embryos developed to a key early stage, the hollowed-ball blastocyst. If they can survive transfer to surrogate southern rhinos and continue developing, it would demonstrate that at least one route to salvaging the subspecies may be possible. But it might not be enough.

The blastocysts are “the first in vitro produced rhinoceros embryos ever,” said co-author Thomas Hildebrandt, of the German Leibniz Institute for Zoo and Wildlife Research. The northern white rhino population is down to just two infertile females (Najin and her daughter Fatu). The last male, Sudan, died in March. The southern subspecies is some 21,000 animals strong. Yet ironically, the genomes of northern animals, albeit based on a handful of samples, are more diverse.

The hybrid embryos, harboring one southern and one northern genome, are halfway to the goal of re-establishing a founding population of the dwindling subspecies. Mating the hybrids for several generations, serially selecting offspring with the highest percentages of northern DNA, could approach reconstituting the genome of the northern white rhinoceros, given time and luck. This is classical genetics sprung from an assisted reproductive technology.

Continue reading at DNA Science, my blog for Public Library of Science. Read More 
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The Genetic Power of Jurassic World: Fallen Kingdom

The latest installment in the Jurassic Park franchise, coming a quarter century after the first film, is about the “genetic power” of the cloned dinosaurs. Only it really isn’t.

The plot is superficially superficial – reviews seem more focused on Bryce Dallas Howard’s improved footwear from the last go-round, pointing out the thin plotline. But many missed the subtleties and subtext of the science.

I scribbled in the dark theater, as I did when reviewing the ridiculous Rampage a few weeks ago. Fallen Kingdom is much better – at least some thinking went into it.

Save the Dinosaurs!

When last we saw the dinos in 2015, they were running amok on Isla Nublar, 150 miles to the west of Costa Rica. Now a huge volcano has started to sputter. What to do? After all, we brought them back, posits Jeff Goldblum, reprising his mathematician-turned-biologist Ian Malcolm persona in the first scene, deploying multisyllabic words when addressing a befuddled senator. The beasts are facing an “extinction level event.”

Continue reading at DNA Science, my blog for Public Library of Science.  Read More 
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