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

Genetic Linkage

Charlie Gard Post-Mortem: Could He Have Been Saved?

August 5, 2017

Tags: Charlie Gard

Charlie Gard would have turned one year old last week.

Two days before the British infant died of a mitochondrial disease on July 28, a short article in MIT Technology Review teased that Shoukhrat Mtalipov and his team at Oregon Health & Science University and colleagues had used CRISPR-Cas9 to replace a mutation in human embryos, a titillating heads-up that didn’t actually name the gene or disease.

A week later, Nature published details of what the researchers call gene correction, not editing, because it uses natural DNA repair. I covered the news conference, with a bit of perspective, for Genetic Literacy Project and Medscape Medical News.

Might gene editing enable Charlie’s parents, who might themselves develop mild symptoms as they age, to have another child free of the family’s disease? Could anything have saved the baby? (more…)

Cystic Fibrosis Among Asians: Why Ethnicity-Based Genetic Testing is Obsolete

July 10, 2017

Tags: cystic fibrosis, genetic testing, carrier screening

Pseudomonas aeruginosa, a bacterium that inhabits the lungs of many people who have cystic fibrosis, but is otherwise rare.
A hypothetical heterosexual couple living in the US or UK takes tests to learn if they are carriers of the more prevalent recessive diseases. They’re relieved to find out that cystic fibrosis (CF) isn’t something they need worry about passing to their children – neither has any of the few dozen mutations the test panel includes.

The couple do not carry the most common 32, 106, or even 139 disease-causing mutations in the CFTR gene, the number depending upon the testing lab. But that could be a problem – a false negative – if the woman and man are anything other than non-Hispanic whites.

More than 2,000 variants (alleles) of CFTR are known, and their prevalence varies in different populations. That’s not because DNA recognizes the race or nationality of the person whose cells it’s in, but because of how we choose our partners. (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…)

Post-Election Health Effects … Not Just Psychological?

June 15, 2017

Tags: Donald Trump, Trump Traumatic Stress Disorder

Buried in the lower right corner of last week’s New England Journal of Medicine – not up on the left, which spawns the headlines – appears “Health Effects of Dramatic Societal Events – Ramifications of the Recent Presidential Election.” David R. Williams, PhD, MPH, and Morgan M. Medlock, MD, M.Div, both from Harvard, describe “post-election health effects” and list ways clinicians can help their patients cope.

“Health effects,” rather than “syndrome” or “disorder,” suggests that the angst many of us have been feeling since November 9 isn’t a medical condition, but is a strange new normal. Others use stronger terms. Sarah Jones in Politicususa attributes the rape nightmares plaguing many women to Trump Traumatic Stress Disorder (TTSD). John Markowitz’s recent editorial “Anxiety in the Age of Trump” in Comprehensive Psychiatry attributes the “floods of patients” and “national – if not global – rising anxiety” to “Post-Trump Stress Disorder.” I prefer Jones’ TTSD, because the distress began well before the shock of the election. (more…)

Wolf Evolution and "Settled Science"

June 14, 2017

Tags: wolf evolution, climate change

Are the red and eastern wolves separate species, or hybrids with coyotes? And what has that got to do with climate change? Actually a lot, in illustrating what scientific inquiry is and what it isn’t.

COMPARING CANID GENOMES

A report in this week’s Science Advances questions conclusions of a 2016 comparison of genome sequences from 28 canids. The distinction between “species” and “hybrid” is of practical importance, because the Endangered Species Act circa 1973 doesn’t recognize hybrids. But DNA information can refine species designations — or muddy the waters. (more…)

Spinach Genome Reveals a Living Fossil

June 3, 2017

Tags: spinach genome

Imagine being spinach.

Sidelined in the produce section of a supermarket, bagged and bunched into a sad uniformity mere feet from the regal, multihued heirloom tomatoes; the purple, orange, and cream-colored cauliflowers; the myriad types of onions, potatoes, squashes and even peas, spinach plants sport a dark green sameness distinguishable only by leaf size.

A WHITER SHADE OF KALE

At farmer’s markets, the lone spinach nestles amongst an ever-growing cornucopia of hipster greens, the kale and arugula, chard and mustard. (more…)

5 New Buzzwords Borrowed from Biology

May 30, 2017

I’ve just finished revising the latest edition of my human genetics textbook, and while checking the glossary, discovered several potential new buzzwords, a few particularly relevant in these strange times.

THE OLD

Co-opting terms from science may have begun with "organic," it’s definition so evolved that I must insert "(carbon-containing)" when I first use the term in a genetics book. Last week for the first time I heard "inorganic," presumably meaning "not genuine." (more…)

An American Horror Story: The AHCA and Anencephaly

May 11, 2017

Tags: neural tube defect, American Health Care Act, anencephaly

Last week I read with incredulity section 215 of The American Health Care Act, the part that states that it “does not include coverage for abortions (other than any abortion necessary to save the life of the mother or any abortion with respect to a pregnancy that is the result of an act of rape or incest).”

How would such a draconian measure, should it become law, affect the field of prenatal diagnosis? (more…)

Pulling the Plug on the First Gene Therapy Drug

May 1, 2017

Tags: gene therapy, Glybera

2017 is supposed to be the year that FDA finally approves a gene therapy. But last week, the company behind the first approved gene therapy in Europe, UniQure, announced that it won't “pursue the renewal of marketing authorization” that expires October 25.

What happened? Is the move a setback for gene therapies in the pipeline? I don’t think so.
(more…)

Dueling BRCA Databases: What About the Patient?

April 23, 2017

Tags: BRCA, breast cancer

The news release Monday morning grabbed my attention:

“Study finds wide gap in quality ofBRCA1/2variant classification between Myriad Genetics and a common public database.”

Myriad Genetics had been exclusively providing the tests, for $3000+ a pop for full BRCA gene sequencing, for 17 years before the Supreme Court invalidated key gene patents back in 2013. Since the ruling a dozen or so competitors have been offering the tests for much lower prices. Meanwhile, Myriad has amassed a far deeper database than anyone else, having been in the business so much longer. And it’s proprietary. (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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