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

DNA Testing Kits as Holiday Gifts Can Bring Surprises

December 16, 2017

Tags: direct-to-consumer genetic testing

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Lately people have been sending me their direct-to-consumer (DTC) genetic testing results for help with interpretation. Although companies like 23andMe and ancestry.com do a pretty decent job of explaining findings, people not familiar with genetics might be confused. And they can be so upset, or scared of the science, that they forget that human behavior lies behind some disturbing information.

So it was that Lisa G., not her real name, emailed me recently, asking about the likelihood that a stranger claiming to be her half-brother really was. He’d gotten the idea from a 23andMe test. So as ads for DTC DNA tests ramp up as the holidays approach, I thought I’d relate this simple example of the feelings that findings can evoke. (more…)

An Argument Against Gene Drives to Extinguish New Zealand Mammals: Life Finds a Way

November 30, 2017

Tags: gene drive, gene editing, CRISPR-Cas9

The mammals of New Zealand have long posed a threat to native species. The Predator Free 2050 program is an effort to rid the island of these invaders – including using the tools of CRISPR-based genome editing to create a gene drive to jumpstart extinctions.

It’s a very bad idea. (more…)

The Peaceable Genomes of Pumpkins

November 24, 2017

“For pottage and puddings and custards and pies
Our pumpkins and parsnips are common supplies,
We have pumpkins at morning and pumpkins at noon,
If it were not for pumpkins we should be undoon."


Pilgrim verse, circa 1633

The pumpkin became a Thanksgiving staple at the second celebration, after the immigrants to the New World had learned about its nutritional value and versatility from the original Americans. (more…)

The Biology of “Stranger Things’’

November 20, 2017

Tags: Stranger Things

The Netflix series Stranger Things, although terrific, might ditch the clichéd doctor-scientist in charge and get themselves a developmental biologist, stat. The disseminated beast that is invading, sliming, and gobbling the residents of a small Indiana town reminds me of one of my favorite organisms, the cellular slime mold. (more…)

Gene Therapy on Stem Cells Replaces a Boy’s Epidermis

November 14, 2017

Tags: epidermolysis bullosa

Genetically corrected stem cells replaced a boy's skin.
A 7-year-old boy whose outer skin layer was nearly gone due to a genetic disease has had it replaced, using his own genetically-modified stem cells, report researchers from Germany, Austria, and Italy in Nature.

He has junctional epidermolysis bullosa (JEB). The thin tissue layer separating the epidermis from the dermis below is extremely fragile and easily damaged, resulting in blistering, peeling, and fraying of the skin, leaving wounds that can be deadly and raising the risk of skin cancer. The researchers replaced the boy’s skin with grafts to his limbs and then the back of his body, followed by closing some of the gaps. In essence, they engineered and knit him a new epidermis – with a lot of help from the boy’s own capacity to heal. (more…)

Revealing the Subtext in DNA Sequences

November 13, 2017

(NHGRI)
Whenever the first copy of a book I’ve written arrives on my doorstep, I’m afraid to look at it. I still haven’t leafed through the 12th edition of my human genetics textbook, delivered more than a month ago.

Why? I’m afraid there will be errors.

Not misspellings or perish-the-thought incorrect grammar, but the sorts of mistakes that would have flown under the radar of the copyeditors, proofreaders, spellchecks, and grammarchecks.

The missed errors are of two types:

1. Those that repeat a word or part of one – codon codon codon, or hippopotapotapotamus.

2. Phrases that mysteriously moved from where they should be to where they shouldn’t, a sentence from one chapter appearing in another, out of context yet likely undetectable by a bored student.

Unusual repeats and transpositions also happen in genomes, as well as flipped DNA sequences, which thankfully I’ve not seen in a book. Conventional DNA sequencing can’t see these glitches because the sequences haven’t changed – they’ve just been relocated. Clinically, the hiding-in-plain-sight of such repeats and rearrangements can delay diagnosis as false negatives accrue. (more…)

What’s In A (Disease) Name?

November 12, 2017

Tags: ribosome, OMIM, Down syndrome, Huntington's disease, Vincent Pieterse, exome sequencing, RPS23

Vincent Pieterse has some unusual traits, and a rare mutation. Are they related as a novel syndrome -- or not?
Marc Pieterse was angry.

His son Vincent’s unusual features – long, thick eyelashes; low-set ears; extra teeth; autistic behaviors; brittle hair; flat back of the head; hearing loss; developmental delay – had led Marc, an engineer and self-taught geneticist, to seek exome sequencing. He knew that strange combinations of traits could mean a mutation.

Sequencing Vincent’s exome – the protein-encoding part of the genome – could reveal if a new mutation had arisen in him, rather than having been inherited from his parents. And that’s what happened. Vincent has his own dominant mutation in a gene called RPS23. He isn’t, however, defined by any disease. He’s a striking, active, and happy young teen who loves watching and listening to birds as he rides his mountain bike to school through a nature reserve. (more…)

Two New Ways to Treat A Deadly Disease: Spinal Muscular Atrophy

November 8, 2017

Tags: spinal muscular atrophy, gene therapy, antisense

I don’t think I’ll ever tire of covering new ways to treat genetic diseases that I’d always thought hopeless. Teamed with expanded newborn screening, the brave new treatments may even be able to prevent symptoms.

Recently reports in the medical journals of success seem to be accelerating, despite the long regulatory (more…)

Will Genetics Ever Be Able to Predict the Next Mass Murderer?

November 1, 2017

Tags: Words or phrases to categorize this post for the tags section

Investigating a mass murder initially looks for obvious triggers in a criminal’s life, then more subtle signs, then psychiatric explanations or a brain tumor. But can errant genes help push someone to bomb marathon runners, gun down elementary school children, set a nightclub afire or rain bullets down on concert-goers?

We still don’t know what drove Stephen Paddock to meticulously plan and carry out the Las Vegas massacre on October 1. He took anti-anxiety medicine and his father was a bank robber. But robbing banks isn’t an inherited trait and millions of people take anti-anxiety medication. But could a hint of what was to come have been found in his genes? (more…)

A 31-Gene Test to Predict Alzheimer’s

October 16, 2017

Tags: Alzheimer's disease, APOE4

When the direct-to-consumer genetic testing company 23andMe received FDA approval back in April to market a test for the e4 variant of the gene APOE, which is associated with elevated risk of developing late-onset Alzheimer’s disease, it gave people a possible peek into their futures.

About 15 percent of the population has one or two copies of the high-risk gene variant. For a long time the risk of developing Alzheimer’s for e4 double-dose individuals was 12 to 15 fold, but only 3 fold for those with one copy. Those figures have declined with re-analysis of the data.

A new 31-gene test can identify individuals at higher risk for the disease, including many who test okay for APOE e4. (Which stands for "apolipoprotein E epsilon 4 allele.")

A MORE POWERFUL TEST (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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