12th edition of my human genetics textbook


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

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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.

Is CRISPR Gene Editing Doomed, Even As Gene Therapy Enters the Clinic?

August 15, 2018

Tags: CRISPR, gene therapy

Anyone watching the recent 60 Minutes segment on CRISPR would conclude that the gene editing technology is on the brink of pouring forth a cascade of cures. But a recent study reveals a mess of missing and moved chromosome parts in the wake of deploying the famed “molecular scissors.”

Invented in 2012, CRISPR brilliantly borrows a bacterial defense against infection. The “clustered regularly interspaced short palindromic repeats” are simple DNA sequences that serve as landing strips in a genome where engineered “guide RNAs” deliver an enzyme to a desired gene, amending or obliterating it. When the enzyme snips across the double helix, natural DNA repair ensues. Cas9 is an oft-used enzyme.

Precision

Unlike conventional gene therapy that adds a gene, sometimes hovering in a DNA loop outside a chromosome, CRISPR swaps in or removes a gene at a precise spot. But it took 27 years for the FDA to approve the first gene therapy, Luxturna, to treat a specific form of hereditary blindness, last December. So CRISPRed drugs won’t be hitting CVS or Walgreen’s shelves anytime soon.

The new report, in Nature Biotechnology, from researchers at the Wellcome Sanger Institute, isn’t the first to find a CRISPR glitch, and it certainly won’t be the last.

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


Rampage: Jurassic Park Lite with a Helping of CRISPR Critters

April 23, 2018

Tags: Rampage, CRISPR

Is a film based on a video game with fleeting mentions of a biotech buzzword compelling sci-fi? No. But I liked Rampage anyway.

The use of CRISPR to edit genes is perhaps the only novel plot point in this latest monster movie. An evil head of a biotech company subverts a scientist’s work to fashion a bioweapon that revs up the growth hormone gene, and more, in three unfortunate animals. Cue Godzilla, King Kong, and the beast in Lake Placid. (more…)

Can CRISPR Conquer Huntington’s?

July 1, 2017

Tags: HD, Huntington's Disease, CRISPR, gene editing

In HD extended huntingtin protein builds up in medium spiny neurons in the striatum.
I set a high bar for writing about mouse studies. I don’t include them in my textbooks or news articles, and only rarely blog about them. But when experiments in mice shine a glimmer of hope on a horrific illness with a long history of failed treatments, I pay attention. That happened last week for a report on editing out of mice the human version of the mutant Htt gene that causes Huntington disease (HD), published in the Journal of Clinical Investigation. (more…)

CRISPR Clarifies Split-Hand/Foot

February 18, 2016

Tags: split hand/foot, CRISPR, genome editing, bioethics

A mother and two daughters who have "lobster claw deformity."
While James R. Clapper, Director of National Intelligence, calls genome editing a "national security threat", bioethicists warn of CRISPR-created superbabies, and prominent researchers argue whether patents trump papers, I prefer to quietly look at applications of the technology that aren’t dramatic enough to enter the endless news cycle, but elegantly reveal the power of the technology. (more…)

Will Layla Save Gene Editing?

November 14, 2015

Tags: gene editing, CRISPR, TALENs

(Great Ormond Street Hospital)
I had planned to blast last Thursday’s news of the use of gene-editing to save a British baby from aggressive leukemia. “Two months later, Layla was cancer-free,” proclaimed one of many enthusiastic reports.

I’m always skeptical when I hear the words “cancer” and “cure” in the same sentence, let alone uttered so soon after treatment and without an accompanying technical paper so I can see the data. But when I considered the timing of unfolding events, I realized that the seemingly premature reporting of Layla’s rapidly restored health just might add an important point to the heated discussion over gene and genome editing. That is, can we keep the promising clinical applications on somatic cells, while forbidding the Frankenstein scenarios of germline manipulation? (more…)

CRISPR Meets iPS: Technologies Converge to Tackle Sickle Cell Disease

March 15, 2015

Tags: CRISPR, iPS, sickle cell disease, genome editing

Researchers from Johns Hopkins University have teamed two powerful technologies to correct sickle cell disease in a lab dish. Linzhao Cheng and colleagues have deployed CRISPR/Cas-9 on iPS cells to replace the mutant beta globin gene, published in Stem Cells.

ACRONYMS AND ABBREVIATIONS

CRISPR conjures up images of fried chicken, but it stands for “clustered regularly interspaced short palindromic repeats” – short repeated DNA sequences interspersed with areas called spacers, like stutters. The pattern of repeats and spaces attracts an enzyme, Cas9, which is like a molecular scissors that cuts wherever short RNA molecules called “guide RNAs” take it. Here’s a fuller description. (more…)

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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