12th edition of my human genetics textbook


Tags

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

Genetic Linkage

Battling Constipation with Synthetic Biology and DNA Manipulation

June 28, 2018

Tags: constipation, microbiome, synthetic biology

Worldwide about 15 percent of people suffer from constipation. Passing dry, compacted stools can be quite painful, but eating more fruit, drinking more water, and/or taking laxatives – common advice from friends and physicians alike – can lead to frustration rather than relief. And drugs such as linaclotide (Linzess) and plecanatide (Trulance), and even probiotics don’t work for everyone because our gut microbiomes (the bacteria in our stomachs and intestines) differ.

A few novel approaches are on the horizon, according to Clinicaltrials.com, including new laxatives, acupuncture, reflexology, Chinese herbs, and a Brazilian tea brewed from fruits of green anise and fennel and flowers of senna and elder tree. Old remedies are given new names, like "Movicol." It’s just sodium bicarb stabilized with the laxative polyethylene glycol (PEG), which is the infamous elixir taken the night before a colonoscopy. It works.

Other experimental strategies are more invasive. “Interferential therapy” zaps the abdomen with four electrodes, and is performed at home for an hour a day for two to three months. Another is a "vibrating capsule,“ presumably inserted into the anatomical area of concern. In another clinical trial, 100 people are testing “perineal self-acupressure,” massaging the anal area to break up and mobilize the stool. And fecal transplants are being tested too.

But a fecal transplant seems the opposite of precision medicine: receiving trillions of bacteria from someone else, each microbial species exuding its own smorgasbord of biochemicals. Although the approach is both ancient and effective, with such a mixed bag of ingredients, evaluation is largely empiric – it helps or it doesn’t, to treat recurrent Clostridium difficile infection and several other indications in clinical trials.

Biotech harnesses tryptamine
Purna Kashyap, M.B.B.S., associate director of the Mayo Clinic Center for Individualized Medicine and his colleagues sought to harness a specific molecule, tryptamine, to loosen stool and speed its transit from inside to outside. “Our goal with this research is to find treatments that act only in the GI tract without creating problems in other parts of the body,” he said. The work is published in the June issue of Cell Host & Microbe, including a video.

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

Genetic Rescue of the Northern White Rhino

June 27, 2018

Tags: rhinoceros

The text you type here will appear directly below the image
People are taking eclectic approaches to saving rhinos from poachers.

Tracking devices on the animals detect an increase in heart rate when danger approaches, like a FitBit wearer encountering a dog that’s sprung it’s invisible fence.

A concoction of rhino keratin (the protein that forms the horn) made in recombinant yeast and rhino DNA (to mark its authenticity) offers a substitute that may keep poachers away.

The Rhino Rescue Project captures rhinos, injects dye into their horns, then releases them, the stain rendering the appendage less desirable to hunters. Dehorning is another approach.

Such efforts may appear to be too late for the brink-of-extinction northern white rhino, but results of a new study published in Genome Research offer hope: genome sequences of nine northern white rhinos reveal a genetic diversity that may provide a way to save them. “Our study demonstrates the emerging role for whole genome sequencing analysis to evaluate the potential for population recovery,” said Cynthia C. Steiner, from the San Diego Zoo Institute for Conservation Research and director of the study. (more…)

New Treatment for Phenylketonuria (PKU) Clears Brain Fog

June 21, 2018

Tags: PKU

In the 1959 novella Flowers for Algernon by Daniel Keyes (and the 1968 film Charly), 32-year-old Charlie Gordon, a janitor at a New York City bakery, undergoes experimental surgery that has boosted the intelligence of a laboratory mouse, Algernon. Soon, Charlie is devouring books, asking questions, and even solving problems at work. But then Algernon dies, and in a short while Charlie returns to his normal state of intellectual dullness. But now he becomes distraught, recognizing his limitations in a way that he didn’t before the surgery.

Dan Peterson is about Charlie’s age, and he, too, has recently experienced a new clarity of thinking thanks to a treatment. In Dan’s case it’s an enzyme substitution therapy called Palynziq (pegvaliase-pqpz), which he injects under his skin daily. FDA approved it on May 24 to treat phenylketonuria (PKU). But unlike Charlie’s brief experience, Dan’s treatment should last. (more…)

Why We Aren't Yet on the Verge of a Preemie Prediction Test

June 21, 2018

Tags: preemie

(Versys Clinics)
Earlier this month, I saw an interesting juxtaposition of newly-published papers making headlines. One was about predicting breast cancer recurrence and the effect on chemo choice, the other on predicting premature birth within two months of the due date.

Apples and oranges, perhaps, but both indications use the same technology: gene expression profiling (measuring messenger RNAs, aka transcripts, which guide synthesis of specific proteins). But the studies are at opposite ends of the research trajectory, with the breast cancer paper representing thousands of patients who’ve taken a test that’s been on the market for years, and the prematurity paper a pilot study of only a few dozen women. (more…)

Gene Therapy for Myotubular Myopathy: Early Signs of Success!

June 11, 2018

Tags: myotubular myopathy, gene therapy

Paul Frase with his son Joshua.
Parents cherish developmental milestones, from a newborn’s grip of an offered finger; to an infant’s holding her head up the first time; to rolling over, creeping, and crawling; then to standing, cruising, and finally walking. Even kicking during a diaper change or yowling requires muscle strength and coordination. But a boy with X-linked myotubular myopathy (MTM) is so weak that even breathing is a huge struggle. If a baby survives the initial hospital stay, care at home becomes a full-time job and is only supportive, delaying the inevitable. That grim picture may be changing. (more…)

Can the Egyptian Fruit Bat’s Unusual Genome Show Us How to Fight Deadly Marburg Virus?

June 11, 2018

Tags: Egyptian fruit bat, Marburg virus, Ebola

The Egyptian fruit bat's immune system enables it to peacefully co-exist with Marburg virus, which can cause a swiftly deadly infection in humans. Although Marburg virus disease affects only a few dozen or hundred people a year, the case:fatality ratio in the scattered outbreaks ranges from 50% to 100%. A recent paper in Cell that explores the bat's genome reveals how its immune system may prevent the virus from harming the flying mammals, which may hold clues for preventing or treating the infection in humans.
(more…)

New Forensic Tool: Using DNA to Predict Hair, Eye and Skin Color

June 1, 2018

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

On May 14, a man walking along the shore on Gabriola Island in British Columbia came upon a washed-up human foot enmeshed in a tangle of logs, the appendage still in a hiking boot. It was the thirteenth disembodied foot found in the Pacific Northwest since 2007, twelve in running shoes.

Could DNA testing predict faces to go with the mysterious floating feet? A new genetic test might help — it can deduce hair, eye, and skin color from forensic or anthropological evidence. (more…)

A New Goal for Gene Therapy: Pet Contraception

June 1, 2018

Tags: pet contraception

Each year in the U.S. 1.4 million cats and 1.2 million dogs are euthanized to control their numbers, yet the stray population is many times larger – despite the fact that spaying or neutering is a rite of passage when adopting a kitten or puppy. Surgical contraception works, but is painful, invasive, and includes the risk of anesthesia.

Might gene therapy provide a one-time, far less invasive way to ensure that cats and dogs do not beget kittens and puppies? That’s one of the goals of the Alliance for Contraception in Cats & Dogs. I’ll be speaking at their annual meeting in July, although I’ll admit that using gene therapy for pet contraception is a new idea for me. (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.

Quick Links