12th edition of my human genetics textbook


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Glenn Nichols, surrounded by his hospice team. The author is in yellow.

Genetic Linkage

Mosquito massacre: Can we safely tackle malaria with a CRISPR gene drive?

October 9, 2018

Tags: mosquito, malaria, CRISPR, gene editing

CRISPR-Cas9 gene editing quickly decimated two caged populations of malaria-bearing mosquitoes (Anopheles gambiae) in a recent study, introducing a new way to solve an age-old problem. But the paper describing the feat in Nature Biotechnology had a broader meaning regarding the value of basic research. It also prompts us to consider the risks and rewards of releasing such a powerful gene drive into the wild.

Instead of altering a gene affecting production of a reproductive hormone, the editing has a more fundamental target: a gene that determines sex. The work was done by Andrea Crisanti and colleagues at Imperial College London. Their clever use of the ancient insect mutation doublesex rang a bell for me — I’d used a fruit fly version in grad school.

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

October Isn’t Just for Breast Cancer Awareness

October 9, 2018

Tags: breast cancer

Many posts at DNA Science have been about families navigating life with a rare disease. I especially think of them during October, when so much attention is focused on breast cancer. One in eight women will develop breast cancer at some point in her life.

I know how important regular mammograms are – a scan late last year led to the surgery that likely saved my life. But I find my anxiety ratcheting up with the pervasive symbols and slogans, the pink apparel, labels, products, lit buildings, even garbage cans. Others in my thousands-strong closed breast cancer Facebook group are antsy too, although we don’t seem to be in the majority.

The pink October movement does a lot of good, in many ways. Still, I’ll skip the marches, for the reasons that others have posted on Facebook: I don’t need a reminder, I don’t want to be defined by an illness, and people are already aware of breast cancer. Instead here are a few other worthy causes that have awareness campaigns in October, not all of the conditions rare.

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

Men Behaving Badly: A Lesson from Duck Sex?

October 1, 2018

I hate the phrase “humans and animals” or derisively calling someone an animal. We’re not plants, fungi, bacteria, or protozoa, nor are we above other members of the animal kingdom, at least evolutionarily speaking. In recent weeks, with eclectic examples of prominent human males behaving badly dominating the news, I think of the wider biological lens.

Were the media moguls who forced parts of their anatomy into their female employees, the beloved TV star drugging and assaulting dozens of women, and the privileged schoolboys allegedly groping girls at long-ago parties just acting as biology dictates? Does the rush of power and/or the confusion of an alcoholic haze prevent some XYs from temporarily accessing the regions of their brains that might allow thinking to overcome the testosterone rush and halt their aggression, while dampening the hippocampus so that they later can convincingly claim to have no recall?

I don’t think so.

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

‘Voluntary Euthanasia’: Are We Ready to Harvest Organs While Donors Are Still Alive?

September 24, 2018

Tags: euthanasia

In the dystopian society of Nobel prizewinner Kazuo Ishiguro’s Never Let Me Go, cloned people are raised to provide organs for the wealthy.

So stark and terrifying is Ishiguro’s imagined world that I never thought I’d read something similar in a work of nonfiction, let alone in a top medical journal. But a Perspective in the September 6 New England Journal of Medicine (NEJM), "Voluntary Euthanasia – Implications for Organ Donation," eerily echoes some aspects of the 2005 novel (and forgettable 2010 film): choosing to donate one’s organs before death, minus the coercion and cloning.

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

A Natural History Study Isn’t Necessarily About Dinosaurs

September 24, 2018

Tags: natural history study

Many scientists trace their childhood inspiration to the towering skeletons of dinosaurs that still reign over the regal lobbies of the American Museum of Natural History, myself included. But “natural history” has a different meaning in medical research, especially in evaluating new treatments for rare diseases. Searching PubMed under “natural history study” turns up a curious 75,000 or so entries, including rare diseases and museum taxidermy.

A medical natural history study looks at how a disease unfolds over time, in real patients, to provide a point of comparison and variability for evaluating new treatments. A neurologist, for example, might know how to handle an otherwise healthy child with ADHD; a youngster with ADHD as part of Sanfilippo syndrome presents a different clinical picture. A natural history study provides an idea of what to expect.

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

Y Chromosomes in the News and #MeToo

September 18, 2018

Tags: Y chromosome

The firing of CBS CEO Les Moonves for his alleged history of revolting attacks on women and the upcoming one-year anniversary of Ronan Farrow’s seminal New Yorker piece on Harvey Weinstein and of Alyssa Milano’s #MeToo tweet echoing Tarana Burke’s 2006 call-to-action, got me pondering the Y chromosome.

Genomically speaking, the diminutive Y is the only thing that distinguishes males from females (see “Y Envy"). Both sexes have X chromosomes, and although mitochondrial DNA passes from females to all offspring, we all have mitochondria. Only the Y is the male’s alone.

If size matters, the Y chromosome loses. The human X has about 1500 protein-encoding genes compared to the Y’s 231, some of which have counterparts on the X. Only a handful of Y genes, in the “male-specific region” of the chromosome, are uniquely male. They include the SRY gene that determines maleness and a few others that control fertility.

So the Y chromosome can tell us some interesting things about the male of the species.

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

Gene Silencing Through RNA Interference Scores First Drug Approval

September 11, 2018

Tags: RNA interference, RNAi

The Food and Drug Administration recently approved the first drug based on RNA interference (RNAi). Unlike media darlings gene therapy and gene editing, RNAi silences genes. The first approval is a milestone two decades in the making.

The new drug, Onpattro (patisiran), treats the tingling, tickling, and burning sensations from the rare condition hereditary transthyretin-mediated amyloidosis, aka hATTR. About 3,000 people have it in the US. Alnylam Pharmaceuticals provides this “first-of-its-kind RNA interference (RNAi) therapeutic.” Like other new nucleic-acid based treatments, it’s pricey. The cost per year for the every-third-week intravenous infusion is $450,000.

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

Matching Cancer Patients to Targeted Drugs: Two New Tools

September 9, 2018

Tags: cancer, machine learning, Cerebro, Keytruda, Gleevec, Herceptin

A choreography of mutational events drives cancer cells to invade and metastasize, changing the biology in ways that enable the errant cells to resist treatments. While the traditional slash-and-burn approaches of chemotherapy and radiation attack rapidly-dividing cells, targeted treatments zero in on the altered proteins that reflect precise genetic changes in tumor cells. These are the somatic (“body”) mutations in just the affected cells, not the inherited mutations present in all of a patient’s cells.

Two new papers introduce tools to better match patients to targeted treatments or immunotherapies, based on interpreting the mutations behind a cancer’s initiation and spread. One is a machine learning tool called Cerebro, the other a scale for physicians to rank the evidence that a particular targeted treatment will work against a tumor with specific mutations.

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

The Cave Where It Happened: The Daughter of a Neanderthal Mom and a Denisovan Dad

August 24, 2018

Tags: Denisovan, Neanderthal

Svante Pääbo and a friend.
Once upon a time, in a cave in the Altai Mountains of southern Siberia, different types of ancient peoples were having sex.

A new report in Nature from Svante Pääbo, the Max Planck Institute for Evolutionary Anthropology superstar, and his team introduces the young teen “Denisova 11.” I’ll call her Eleven, in honor of the beloved character in the TV show Stranger Things. She was a type of archaic human called a Denisovan, pronounced “Denise-o-van.”

The title of the new paper tells the whole tale: “The genome of the offspring of a Neandertal mother and a Denisovan father.”

Introducing Denise

The research team introduced the first Denisovan, named Denise, in 2010, based on a preliminary genome sequence from her finger bone, discovered in 2008 in the cave. Denise lived 32,000 to 50,000 years ago and had dark skin and brown eyes and hair. Her genome included some Neanderthal sequences, so it was clear there’d been some mixing of genomes going on.

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

Were There Two Routes into North America? Genetics Meets Archaeology

August 24, 2018

Tags: Beringia, land bridge

Popular accounts of the peopling of North America paint a picture of a lone long-ago trek across the Bering Land Bridge and then south along the Pacific coast, a view based largely on DNA evidence. But other clues point to people also traversing “ice-free corridors” that emerged from melting glaciers like terrestrial tentacles.

A new paper in Science Advances reviews the evidence for more than one way into North America. It concludes that people followed at least two routes, coastal and interior, and that the view over the land bridge “commonly disseminated in the popular press is a prematurely narrow interpretation of current evidence.” The journal held a news conference with three of the investigators.

"We’ve seen conflicting narratives about the timing and the nature of the peopling of the Americas. We wanted to evaluate this claim and provide a framework to discuss the process – not based on speculation but on a critical review of current evidence. Rather than confusion, there is growing congruence of the archeological, paleoecological, and genetic records," said co-author and archaeologist Ben Potter, professor of anthropology at the University of Alaska, Fairbanks.

More philosophically, the report beautifully illustrates scientific inquiry, operating in a blind-man-and-the-elephant sort of way, revealing not alternate facts, but multiple solutions to a shared challenge – a search for habitable land. It also touches on ways to avoid so-called in
"helicopter research,"
in which wealthy nations send expeditions to probe the health and lives of poorer people, without involving them in the work.

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

instruction
Project to engage students in helping families with rare genetic diseases
Book Club Reader's Guide
Many challenging questions to stimulate thought and discussion.
Instructor's Guide
38 discussion questions to get students thinking and talking about gene therapy, including the science, ethical issues, and the drug approval process.
Narrative science
The Forever Fix is the uplifting true story of 8-year-old Corey Haas, who was cured of hereditary blindness just 4 days after gene therapy.
College Textbooks
A spectacularly-illustrated, clearly written human anatomy and physiology textbook, used in pre-health profession programs throughout the U.S.
A highly engaging, clearly written, beautifully illustrated introduction to the science of human genetics for the non-scientist. Now in its 11th edition, 12th to be published in September 2018.
Nonfiction
An ideal starting point for anyone who wants to know more about genes, DNA, genomes, and the genetic ties that bind us all.

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