Ricki Lewis's Blog, page 52
February 26, 2013
Rare Diseases: Unicorns, Not Zebras
�When you hear hoofbeats, think horses, not zebras.�
Every doctor-to-be hears this mantra. Rare Disease Day, February 28, celebrates the 7,000 or so diseases that are zebras, each affecting fewer than 200,000 people.
Giant axonal neuropathy (GAN) isn�t a zebra, but a unicorn. Eight-year-old Hannah Sames inherited one mutation from each of her parents in a gene that encodes a protein called gigaxonin. As a result, the axons of her motor neurons are slowly filling up with haphazardly-arrayed intermediate filaments. The cells bulge, blocking the messages to her muscles. She�s one of only 50 in the world known to have GAN. But if all goes according to schedule, Hannah and several other youngsters are going to have gene therapy to correct the disease. Read about it at Hannah�s Hope Fund.
Two years ago, at the annual meeting of the American Society of Gene and Cell Therapy in Washington, I had the honor of watching Hannah�s marvelous mom Lori as she watched a child helped by gene therapy � Corey Haas, whose story bookends a brief history of the technology in "The Forever Fix: Gene Therapy and the Boy Who Saved It".
Here�s an excerpt, for Rare Disease Day.
Every doctor-to-be hears this mantra. Rare Disease Day, February 28, celebrates the 7,000 or so diseases that are zebras, each affecting fewer than 200,000 people.
Giant axonal neuropathy (GAN) isn�t a zebra, but a unicorn. Eight-year-old Hannah Sames inherited one mutation from each of her parents in a gene that encodes a protein called gigaxonin. As a result, the axons of her motor neurons are slowly filling up with haphazardly-arrayed intermediate filaments. The cells bulge, blocking the messages to her muscles. She�s one of only 50 in the world known to have GAN. But if all goes according to schedule, Hannah and several other youngsters are going to have gene therapy to correct the disease. Read about it at Hannah�s Hope Fund.
Two years ago, at the annual meeting of the American Society of Gene and Cell Therapy in Washington, I had the honor of watching Hannah�s marvelous mom Lori as she watched a child helped by gene therapy � Corey Haas, whose story bookends a brief history of the technology in "The Forever Fix: Gene Therapy and the Boy Who Saved It".
Here�s an excerpt, for Rare Disease Day.
February 21, 2013
New Guidelines on Testing Kids� DNA � the Cliff�s Notes Version
Exomes are big news. Sequencing of the protein-encoding part of the genome is increasingly solving medical mysteries in children. It began with Nicholas Volker and his recovery from a devastating gastrointestinal disease with a stem cell transplant once his exome sequence revealed his problem. And recent Medscape assignments reveal the trend: 7 of 12 kids� exomes leading to diagnosis at
Duke University
from May 10, 2012; whole genomes of 5 infants from the neonatal intensive care unit at Children�s Mercy Hospital and Clinics in Kansas City, Missouri from October 3, in under 2 days each, focusing on 600 single-gene diseases; and 300 patients at the Whole Genome Laboratory at the Baylor College of Medicine, with 300 more waiting -- 85% of them kids, from November 9, 2012. (You have to sign in to Medscape; it�s free.)
But wait.
Before we all run out to get our exomes and/or genomes sequenced,
Duke University
from May 10, 2012; whole genomes of 5 infants from the neonatal intensive care unit at Children�s Mercy Hospital and Clinics in Kansas City, Missouri from October 3, in under 2 days each, focusing on 600 single-gene diseases; and 300 patients at the Whole Genome Laboratory at the Baylor College of Medicine, with 300 more waiting -- 85% of them kids, from November 9, 2012. (You have to sign in to Medscape; it�s free.)
But wait.
Before we all run out to get our exomes and/or genomes sequenced,
February 4, 2013
Genetic Testing: Carrier Confusion & Generation Reversal
In the usual trajectory of passing on genetic information, the older tell the younger, when the time is right. Typically, a patient has a genetic test because family history, ethnic group, or some other clue suggests to an astute practitioner an increased risk of something specific.
If a test reveals a mutation that could cause a disease, then the patient and perhaps her partner discuss how, when and what to tell their children � in the best of circumstances, with the help of a genetic counselor.
If a test reveals a mutation that could cause a disease, then the patient and perhaps her partner discuss how, when and what to tell their children � in the best of circumstances, with the help of a genetic counselor.
February 3, 2013
Another Bump in the Road for Gene Therapy?
I am astonished, once again, by the complexity and unpredictability of science.
Last week, a paper in the Proceedings of the National Academy of Sciences (PNAS) reported that gene therapy to treat a form of blindness called Leber congenital amaurosis type 2 (LCA2) doesn�t stop degeneration of the rods and cones � the photoreceptor cells that provide vision. Gene therapy sends the genetic instructions for a protein called RPE65 into a layer of cells that supports the rods and cones � the retinal pigment epithelium, or RPE. The protein is essential for the eye to use vitamin A. And the gene therapy works, so far.
Last week, a paper in the Proceedings of the National Academy of Sciences (PNAS) reported that gene therapy to treat a form of blindness called Leber congenital amaurosis type 2 (LCA2) doesn�t stop degeneration of the rods and cones � the photoreceptor cells that provide vision. Gene therapy sends the genetic instructions for a protein called RPE65 into a layer of cells that supports the rods and cones � the retinal pigment epithelium, or RPE. The protein is essential for the eye to use vitamin A. And the gene therapy works, so far.
January 25, 2013
My Cat Has AIDS (Part 1)
Juice was an impulse buy.
It was early July 2003, and we were headed to the mall for a gift for Carly, about to turn 15. We parked near a bus equipped as an animal shelter.
Inside, kitten-filled cages lined the walls, except for one, which had a large, orange and white cat stuffed into it. Carly made a beeline for him and the attendant hoisted him out and handed him over. I reminded Carly that we already had 5 felines, but we knew he�d be left behind as the kittens were adopted.
It was early July 2003, and we were headed to the mall for a gift for Carly, about to turn 15. We parked near a bus equipped as an animal shelter.
Inside, kitten-filled cages lined the walls, except for one, which had a large, orange and white cat stuffed into it. Carly made a beeline for him and the attendant hoisted him out and handed him over. I reminded Carly that we already had 5 felines, but we knew he�d be left behind as the kittens were adopted.
January 15, 2013
Retinal Stem Cells and Eye of Newt
More than a decade before Sally Temple, PhD, and her husband Jeffrey Stern, MD, PhD, discovered stem cells in human eyes, they suspected the cells would be there. They knew it from the salamanders.
A SPECIAL FONDNESS FOR AMPHIBIANS
When William Shakespeare included �eye of newt� ingredients of the Three Witches� brew in Macbeth, he probably knew what he was doing. Dr. Temple, who grew up in northern England, said it�s long been common knowledge there that newts can regrow their parts. In the late 1800s, biologists began to study regeneration in salamanders.
By the 1950s, embryologists had discovered that certain amphibian eyes regenerate thanks to a single layer of cells, called the retinal pigment epithelium (RPE), which hugs the photoreceptors (the rods and cones).
A SPECIAL FONDNESS FOR AMPHIBIANS
When William Shakespeare included �eye of newt� ingredients of the Three Witches� brew in Macbeth, he probably knew what he was doing. Dr. Temple, who grew up in northern England, said it�s long been common knowledge there that newts can regrow their parts. In the late 1800s, biologists began to study regeneration in salamanders.
By the 1950s, embryologists had discovered that certain amphibian eyes regenerate thanks to a single layer of cells, called the retinal pigment epithelium (RPE), which hugs the photoreceptors (the rods and cones).
The Crud: Viral or Bacterial?
My immune system is still on hyperdrive from what may have been the flu three weeks ago. I qualify my self-diagnosis because I never had a test to tell whether viruses or bacteria had invaded my body.
I�ve long wondered why such diagnostics aren�t, by now, in routine use. Molecular biology was pioneered on the genetic details of bacteria and their viruses in the 1970s, and by now most of our pathogens have had their genomes sequenced.
I�ve long wondered why such diagnostics aren�t, by now, in routine use. Molecular biology was pioneered on the genetic details of bacteria and their viruses in the 1970s, and by now most of our pathogens have had their genomes sequenced.
January 2, 2013
Comparing Adam Lanza�s DNA to Forensic DNA Databases: A Modest Proposal
In 1729, Jonathan Swift of Gulliver�s Travels fame published a satirical essay called "A Modest Proposal." He suggested that a cure for poverty was for poor people to sell their children to rich people as food.
I�m borrowing Swift�s essay title to bring up another outrageous idea: analyzing forensic DNA databases for a genetic signature of criminality.
I�m borrowing Swift�s essay title to bring up another outrageous idea: analyzing forensic DNA databases for a genetic signature of criminality.
December 26, 2012
The Curious Genetics of Werewolves
Growing up in the 1960s, I collected monster cards: The 60-foot-man and the 50-foot woman; body doubles gestating in giant seed pods; unseen Martians that sucked people into sand pits and returned them devoid of emotion, with telltale marks on the back of the neck. One card featured a very young Michael Landon in �I Was a Teenage Werewolf.�
Forgive my lapse in political correctness, but I recalled those cards when I saw the word �hypertrichosis� in a recent paper in PLOS Genetics because, unfortunately, the condition is also known historically as �werewolf syndrome.�
Forgive my lapse in political correctness, but I recalled those cards when I saw the word �hypertrichosis� in a recent paper in PLOS Genetics because, unfortunately, the condition is also known historically as �werewolf syndrome.�
December 18, 2012
Gene Therapy for Canavan Disease: Max�s Story
I�m thrilled about the encouraging gene therapy results just published in Science Translational Medicine from Paola Leone, PhD and R. Jude Samulski, PhD, and colleagues. �Long-term follow-up after gene therapy for Canavan Disease� updates a project that has its origins in the mid 1990s. Canavan disease is a brain disorder present from birth.
I�ve been following some of the kids who�ve had the gene therapy. One patient in particular � Max Randell � has been in my human genetics textbook since age three, his progress updated with each edition.
I�ve been following some of the kids who�ve had the gene therapy. One patient in particular � Max Randell � has been in my human genetics textbook since age three, his progress updated with each edition.
