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Genetic Linkage

Revising Textbook Coverage of Prenatal Diagnosis in an Anti-choice Climate

I've become a stalker.

 

When I recently stopped at an intersection behind a car with bumper stickers "Make Abortion Criminal Again" and "Worship GOD, not GOV," I followed the offensive vehicle into the parking lot of Target. Out emerged an older white man who took no notice of me approaching, phone camera out.

 

I'm willing to bet that he never had to carry to term, in his body, a fetus known to have a severe chromosomal anomaly.

 

I'd bet that he was never forced to remain pregnant, give birth, and then watch the newborn die.

 

Yet the man in the Target lot, if those bumper stickers were indeed his, feels empowered to take the choice to abort this tragedy from women he doesn't know.

 

But I thank him for the lead-in to this blog post.

 

What's To Become of Prenatal Diagnosis?

 

I'm revising my human genetics textbook for a 13th edition, and I've hit a roadblock at this sentence:

 

"If a test reveals that a fetus has a serious medical condition, the genetic counselor discusses possible outcomes, treatment plans, and the option of ending the pregnancy."

 

I describe those prenatal tests in depth earlier, focusing on how testing fetal DNA in a woman's circulation is replacing the riskier amniocentesis and CVS. But I now have to add "possible" before "option."

 

To continue reading, go to my DNA Science blog at Public Library of Science, where this post first appeared.

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Clinical Trial Set to Start for CLN1 Batten Disease

On May 21, Abeona Therapeutics announced the go-ahead from the Food and Drug Administration (FDA) for a clinical trial to test a gene therapy for a form of Batten disease called CLN1 disease, aka infantile neuronal ceroid lipofuscinosis. The King family and their organization Taylor's Tale has supported the research that made the clinical trial possible since their beloved Taylor was diagnosed at age 7 in 2006.

 

The eight forms of Batten disease are ultrarare – together they account for only 1 in 100,000 individuals. Each is caused by mutation in a different gene, but all cause neurodegeneration. The conditions were originally named for what was thought to be the typical age of onset, before much was known about the genetics or the natural histories. CLN1 is now recognized to manifest in infancy, late infancy, and in children (juvenile), and Taylor had the juvenile form.

 

CLN1 is the classic "infantile" form. But Taylor King was no longer an infant when she experienced the first subtle sign, a new difficulty with numbers in the first grade. Taylor had taught herself to read at age three.

 

"There were signs of the secret hiding in Taylor's genes even then, but they were too complex and too twisted for any of us to understand," wrote her sister Laura in her book Run to the Light, which I reviewed here.

 

To continue reading, go to my DNA Science blog for Public Library of Science, where this post first appeared.

 

 

 

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Anatomy of an Impossible Burger

Burger King is going to sell the Impossible Burger and McDonalds is soon to follow with its own meatless patty. So I thought I'd check out the brilliantly-branded burger, both in the patent and on my plate.

 

A Variation on the Heme Theme

 

My first encounter with the Impossible Burger was pinching a piece off my dinner companion's plate in February. It looked and seemed to bleed like a real burger. As I chewed, I googled the product on my phone, stopping at the word "heme."

 

Gulp.

 

I stopped chewing. Once I got past the image of a bovine muscle pulsating on the plate, I envisioned the iron atom within its porphyrin ring, both lying within a surrounding globular protein, a little like a tootsie roll pop.

 

Heme in various guises is found in all species, from bacteria to beans to buffalos. It's at the heart of the myoglobin in our muscles and the hemoglobin in our blood, packed most densely into the muscle cells of beef cattle.

 

To continue reading, go to my DNA Science DNA Science blog at Public Library of Science.

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How this promising gene therapy for a rare neuromuscular disease was fueled by passionate parents and a dog

Many treatments for rare diseases begin with families who work tirelessly, sometimes for decades, to fund the initial studies leading to the clinic. For X-linked myotubular myopathy (MTM), an amazing couple and their brave and brilliant son; a team of geneticists, physicians, and veterinarians; and some incredible dogs lie behind the encouraging interim findings presented at the recent American Society of Gene and Cell Therapy annual meeting in Washington, DC.

 

Several boys who were barely able to move and were completely dependent on ventilators are now eating, making sounds and walking with assistance, while the protein their bodies had been unable to manufacture is accumulating in their muscle cells. Audentes Therapeutics presented the results at a Presidential Symposium that highlighted several strides during the past year against rare neuromuscular diseases, including muscular dystrophies and spinal muscular atrophy. The interim data for MTM are here.

 

To continue reading, go to Genetic Literacy Project, where this article first appeared.

 

 

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Thriving in Thin Air Goes Back 160,000 Years to the Denisovans, New Study Finds

Fleshing out the details of ancient humanity has typically begun with fossil finds and then, years later, sequencing genes and genomes. That was the case for Neanderthals, but now the reverse has happened for the Denisovans.

 

A new paper in Nature describes a partial upper jawbone from a Denisovan who lived 160,000 years ago. It was discovered quite far from the known home of these archaic humans in Siberia, in Baishiya Karst Cave in Xiahe, China, on the Tibetan Plateau.

 

The partial jawbone is the oldest human fossil from the area. It's existence indicates that ancestors of today's Sherpa from 10,000 or so years ago weren't the first to be able to survive at high-altitude, low-oxygen environments, as had been thought.

 

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

 

 

 

 

 

 

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‘The broken promise of anonymity’? Bioethicist’s call to guard identity of sperm and egg donors is misguided

An academic bioethicist has published a controversial paper supporting the rights of sperm and egg donors to remain anonymous over the rights of their offspring to learn donor identities.

 

"Genetic databases and the future of donor anonymity" appears in the journal Human Reproduction. The author is Guido Pennings, from the department of philosophy and moral science at the Bioethics Institute Ghent. My opinion is that Dr. Pennings' opinion fails to capture the complexity of donation.

 

"Not Parent Expected"

From 1950 until 1958, a man whom I do not know donated his sperm to help infertile couples in Brooklyn. As a result, my sister and I have, at last count, six half-siblings.

 

To continue reading go to Genetic Literacy Project, where this post first appeared.

 

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DNA Day Has a New Meaning For Me This Year: I’m an NPE

"Not parent expected" – NPE – is a surprise that thousands of us have gotten as a result of consumer ancestry DNA testing. We discover that we are the offspring of a sperm donor, or sexual violence, or a long-ago fuzzy night at a party, a brief interval between partners, an affair, or a single experimental partner-swap long forgotten.

 

We find out that we aren't who we thought we were, at least in our genes. I know I'm the same person, of course, but something has changed.

 

DNA Day to me this year means that I share approximately 25% of the DNA signposts used to assess ancestry – some 700,000 or so data points that mark genetic diversity – with six half-siblings, and possibly more.

 

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

 

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Revived pig brains may unleash uncomfortable questions for how we define death

When Yale researchers announced that they'd kept pig brains quasi-functional for several hours after they'd been separated from the bodies, writers wrote, bioethicists weighed in on the fine line between life and death, and animal rights activists objected.

 

But I thought about the pilot episode of Star Trek.

 

Pigs have long been models in cardiovascular disease research, because their hearts and blood vessels are about the same size as ours. My favorite experimental pig, though, lent her liver.

 

Sweetie Pie had been genetically modified so that her cells were festooned with human proteins, preventing organ rejection. In 1997, when she was 15 weeks old, her detached but functioning liver kept 19-year-old Robert Pennington, suffering from acute liver failure and desperately needing a transplant, alive for 6.5 hours. The young man's blood was cleansed outside of his body through Sweetie Pie's living liver until a human one became available.

 

tz pigPigs mixing with humanity figure into sci-fi and even comedy. The 1960 Twilight Zone episode "Eye of the Beholder" visited a society in which people have pig faces, and the few with human faces are condemned to live out their lives out of sight in their own villages. And on Seinfeld, Kramer reported a pig man on the loose on the top floor of a hospital.

 

Introducing BrainEx

The title of the Nature paper says it all: "Restoration of brain circulation and cellular functions hours post-mortem."

 

 

To continue reading go to Genetic Literacy Project, where this post first appeared.

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An Ultrarare Liver Disease, PFIC2: Trinity’s Story

Ultrarare genetic diseases often appear with a series of symptoms that might seem unconnected.

 

Trinity's troubles began right away: GERD (gastroesophageal reflux disease) so severe that she would frequently stop breathing. The first sign that something complicated was going on began at five months. "She started having bruises all over her body. These later grew and then within a day or two, turned into huge hematomas," Brooke recalled. The baby could barely sleep or eat and Brooke and her mother took shifts in providing the round-the-clock care.

 

Then the pruritis started, an intense, unremitting itching emanating from deep within the skin. Brooke had to dress the child in special mittened onesies to keep her from tearing her skin off. In adults, pruritus leads to thoughts of suicide.

 

Fortunately, diagnosis was relatively fast for the rare disease world. Trinity's local pediatrician sent her to the emergency room at Anne Arundel Medical Center, where they found highly abnormal clotting levels, indicating a liver problem. Then she was referred to Johns Hopkins Medical Center and finally to Cincinnati Children's Hospital. Liver function tests, scans, liver biopsy, and extensive genetic testing, plus consideration of the little girl's symptoms, led to her diagnosis at 7 months old: progressive familial intrahepatic cholestasis type 2 (PFIC2).

 

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

 

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NASA twins study highlights key risks for long-term space travel: Cosmic rays and microgravity

When NASA reported preliminary observations about the famous "twin astronaut" study a year ago, the media rushed in, reporting the effort with mind-boggling inaccuracy. The agency was quick to correct the confusion of gene mutations with changes in gene expression, promising a full paper once the findings were more fully scrutinized. Long-awaited, "The NASA Twins Study: A multidimensional analysis of a year-long human spaceflight," appears in the April 11 issue of Science.

 

To recap, Scott Kelly (Space Twin) spent a year aboard the International Space Station (ISS) while his identical twin Mark (Earth Twin) stayed in Arizona. Both men are 50 years old. Mark, also an astronaut, is married to Gabrielle Giffords and is running for the Senate in 2020.

 

A data deluge

 

With last year's overreaction, it's understandable that announcement of the full paper to reporters ahead of publication set the stage for a news blitz. The four press releases, images and videos, a list of quotes from NASA scientists, phone news conferences from Science and NASA, a summary, web materials, and a short feature article in Science sent my hype-o-meter into overdrive.

 

Much of the news isn't news – Genetic Literacy Project covered it a year ago. Plus, many of the monitored biological functions didn't change much in space or did so only transiently.

 

To continue reading, go to Genetic Literacy Project, where this post first appeared.

 

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