12th edition of my human genetics textbook


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

Genetic Linkage

Can Liquid Biopsies Compete with Scopes and Scans in Cancer Diagnosis?

March 15, 2018

Tags: liquid biopsy

March is National Colorectal Cancer Awareness Month, the perfect time to bring up the value of colonoscopies and mammograms. These procedures may seem old school for old folks, but they save lives – more directly than genetic testing. Scopes and scans saved mine and my husband’s (more…)

Good and Potentially Bad about FDA's Greenlighting of 23andMe Direct-to-Consumer BRCA Mutation Tests

March 14, 2018

Tags: 23andMe, BRCA, breast cancer, direct-to-consumer genetic testing

News that consumers will soon be able to purchase a genetic test for three BRCA mutations may seem like déjà vu. That's because it is.

This is the second time that direct-to-consumer genetic-testing company 23andMe has offered screening for the mutations linked to breast cancer. The difference now from when it was yanked off the market in 2013? FDA approval.

That's huge. (more…)

How the Vampire Bat Came to Feed on Blood, and What We Can Learn From Its Droppings

March 2, 2018

Tags: forensic entomology

Why do the three species of vampire bats eat only blood, compared to the 1,240 other species that are perfectly happy to eat such things as figs, mangoes, dates, bananas, birds, fish, frogs, lizards, and even other bats? Many thrive on beetles, moths, and mosquitoes. A single brown bat zooming across a backyard on a summer’s eve can eat 500 mosquitoes in an hour.

Types of Vampire Bats

The three species of vampire bats descended with other bats from a shared ancestor some 26 million years ago. Four million years later – fast in evolutionary time – the three species had refined the ability to survive by drinking blood.

Vampire bats are so stealthy, and their cuts so tiny, that it isn’t uncommon for prey to sleep through the feeding. They live from southern Argentina to northern Mexico, but may venture near Texas and Florida as the climate changes. Fossils indicate they lived in the US 5000 to 30,000 years ago. (more…)

Tracking RNA to Pinpoint Time of Death: Better Than Bugs?

February 28, 2018

Tags: forensic entomology

DNA is a persistent molecule. Genome sequencing is possible for creatures as ancient as mummies and mammoths. But the messenger RNA (mRNA) molecules that translate a gene’s information into a specific protein are more ephemeral, waxing and waning in a tissue over time, even after death, due to the instability of the sugar part of the molecule.

A multinational team has adapted the changeability of gene expression – mRNA production – into a computational tool that uses transcriptomes – the sets of mRNAs in particular body parts – to deduce time since death. In forensics terms, that’s the postmortem interval (PMI). Roderic Guigó led the team that includes researchers from Portugal, Spain, and the Broad Institute at Harvard. Their report appears in Nature Communications.

The Worms Crawl In, The Worms Crawl Out (more…)

From Blue Lights to Gene Therapy: The Intriguing History of Crigler-Najjar Syndrome

February 28, 2018

Tags: Crigler-Najjar syndrome, gene therapy, rare diseases

Seeing Crigler-Najjar syndrome among recent news releases announcing upcoming gene therapy efforts conjured immediate images of an Amish farmhouse with a spooky blue glow emanating from an upstairs bedroom, where a small child, clad only in diapers and wearing goggles, slept beneath a “light canopy” suspended from the ceiling. The light – phototherapy or “bili lights” – breaks down the accumulating bilirubin that the tiny yellow body beneath cannot.

Most cases of neonatal jaundice are due to a transient blood type incompatability or blocked bile ducts, and vanish within days. Not so

Crigler-Najjar syndrome, which hampers the ability to convert the bile pigment bilirubin into a soluble form that easily exits in feces. (more…)

CRISPR Gene Editing of Neurons in Prader-Willi Syndrome

February 22, 2018

Tags: Prader-Willi syndrome

Prader-Willi syndrome illustrates genomic imprinting, when the gender of a parent is important.
I’m happy to see that fears about using CRISPR to edit human genes have dampened over the past year, but it’s still fun perusing the hyperbolic headlines:

They’re going to CRISPR people. What could possibly go wrong?

The Very Real Dangers of New Gene-Editing Technology

“How Gene Editing Could Ruin Human Evolution”

Since being fortunate enough a few years ago to find myself one of only two journalists in the press room at a genetic conference with two of CRISPR/Cas9’s inventors, I’ve made an effort to highlight exciting, beneficial uses of gene editing techniques, such as applications in "http://blogs.plos.org/dnascience/2017/06/29/can-crispr-conquer-huntingtons/">Huntington’s disease, sickle cell disease, and split-hand/foot malformation. (more…)

Gene Therapy for the "Butterfly Children"

February 22, 2018

Tags: epidermolysis bullosa

Videos of the "butterfly children” are difficult to watch. The name comes from the delicate skin of people who have epidermolysis bullosa, which is reminiscent of the fragility of a butterfly’s wings. The slightest touch evokes painful blisters and peeling skin.

“I was born with the worst disease you never heard of,” says Rafi Lily in one video. “I know mom doesn’t want to hurt me, but taking off bandages is hard. It feels like fire is beating me up and sharp dogs teeth are digging into me. But we’ll have to do it all over tomorrow and the next day and every day for the rest of my life.” (more…)

Incurable Arthritic Knees? Gene Therapy Offers New Hope

February 7, 2018

Tags: gene therapy, osteoarthritis

Imagine a single injection into the knee vanquishing painful arthritis – forever. Gene therapies aimed at two molecular targets will likely make that possible, with one, Invossa, already approved in South Korea.

“Arthritis” is a catch-all term for more than 100 varieties of joint inflammation. In the US, more than 30 million people have osteoarthritis (OA). The knee is particularly vulnerable, with arthritis there plaguing 10% of men and 13% of women aged 60 years or older.

Four events contribute to arthritis: inflammation, an increase in the volume of synovial fluid that fills joints, breakdown of the joint, and underlying bone damage. (more…)

NBC News' Richard Engel's Son Diagnosed With Rett Syndrome. Why That's Such a Rarity

February 2, 2018

Tags: Rett Syndrome, Richard Engel

The Today Show recently reported the sad story of Henry Engel—the toddler son of correspondent Richard Engel and his wife Mary Forrest who was diagnosed a few months ago with Rett syndrome.

The segment mentioned, in passing, that it’s rare for a boy to have this genetic condition, but never followed up. A report in People provides a bit more explanation, but still not enough. (more…)

A Closer Genetic Look at the Quagga, an Extinct Zebra

January 26, 2018

Tags: zebra, quagga

Like the dodo bird, heath hen, and woolly mammoth, the quagga vanished so recently that glimpsing its evolution is possible, using DNA from museum specimens and breeding modern relatives to select individuals bearing ancestral traits.

Named and described in 1788, a quagga looks like someone took an eraser to the rear end and hind legs of a zebra, brushing away the telltale stripes. Charles Darwin deemed the quagga a separate species, but today Equus quagga quagga is considered an extinct subspecies of the plains zebra. The living five subspecies roam south and eastern Africa, while the other zebra species, mountain and Grevy, live in more limited areas. When I visited Cape Town a few years ago, I was amazed to see zebras standing in ordinary backyards, like deer appear here. (more…)

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.
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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