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

Genetic Linkage

Rare Disease Day 2017: Talia's Story

February 28, 2017

Tags: gene therapy, Charcot-Marie-Tooth Disease, trisomy 21, Down syndrome, CMT4J

Talia Duff with Cynthia the Hippo
This year for Rare Disease Day – February 28th – DNA Science honors Cure CMT4J: Advancing Gene Therapy for Rare Diseases, run by Jocelyn and John Duff. Their daughter Talia’s “diagnostic odyssey” was unusually long because Down syndrome obscured a second condition, an extremely rare form of Charcot-Marie-Tooth (CMT) disease. (more…)

Defying Mendelian Genetics and "Embryo Engineering"

February 19, 2017

Tags: embryo engineering, de novo mutation, uniparental disomy Bainbridge-Ropers syndrome, giant axonal neuropathy

(credit: Children's Mercy Kansas City)
Mendel’s laws, like any laws in science, make predictions possible. A woman and man both carry a recessive mutation in the same gene, and each of their children has a 25% chance of inheriting both mutations and the associated health condition.

In contrast to our bizarre new world of “alternate facts,” science is both logical and rational. If an observation seems to counter dogma, then we investigate and get to the truth. That’s what happened for Millie and Hannah, whose stories illustrate two ways that genetic disease can seem to veer from the predictions of Mendel’s first law: that genes segregate, one copy from each parent into sperm and ova, and reunite at fertilization. (I’ll get to embryo engineering at the end.)

Millie’s situation is increasingly common – exome or genome sequencing of a child-parent “trio” reveals a new (“de novo”), dominant mutation in the child, causing a disease that is genetic but not inherited.

Hannah’s situation is much rarer: inheriting a double dose of a mutation from one parent and no copies of the gene from the other. (more…)

Pig People?

February 4, 2017

Tags: pig/human chimera

When Medscape asked me late last week to cover the making of early embryos that have cells from pigs and humans, I couldn’t help but flash back to the Pigman episode of Seinfeld. "The government's been experimenting with pig-men since the '50s!" warned a terrified Kramer after finding one such creature hidden on the top floor of a hospital.

We didn't see Kramer’s porcine/human chimera of the 1990s, but a 1960 episode of the Twilight Zone, The Eye of the Beholder, provides an earlier illustration of the mixing of the species. (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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