Ricki Lewis's Blog, page 41
September 9, 2017
A Genetic Disease With a Domino Effect: Multiple Sulfatase Deficiency
Willow is a beautiful name. Meaning slender and graceful, like the tree, it evokes images of a little girl running through the woods with streams of hair behind her. But Willow Cannan, who lives in Mississippi with her parents and two older sisters, can�t run or do very much on her own.
A MASTER MOLECULE MISSING
Willow was born on August 21, 2013. At first she seemed fine, except for difficulty nursing.
�Nothing in itself was significant, but a combination of things over time got worse. She crawled a little late. She did walk, but late, at 18 months. She had frequent ear infections, and dry skin that was very bad on her back and her scalp. And she never talked. No words, not even dada. She just made a few sounds,� recalled her mother, Amber Olsen.
The clues started to accrue between 18 and 24 months, when speech therapy didn�t help. Was the problem fluid in her ears, or enlarged adenoids? Willow had her adenoids out the day after she turned 2.
Amber and her husband Tom Cannan probably didn�t know it at the time, but they were about to start the diagnostic odyssey that millions of rare disease families share. It starts with convincing a pediatrician to look beyond the �horses� that are the common childhood conditions to recognize that a child is a zebra or unicorn, with a collection of rare peculiarities that might actually be trumpeting an underlying genetic glitch.
A MASTER MOLECULE MISSING
Willow was born on August 21, 2013. At first she seemed fine, except for difficulty nursing.
�Nothing in itself was significant, but a combination of things over time got worse. She crawled a little late. She did walk, but late, at 18 months. She had frequent ear infections, and dry skin that was very bad on her back and her scalp. And she never talked. No words, not even dada. She just made a few sounds,� recalled her mother, Amber Olsen.
The clues started to accrue between 18 and 24 months, when speech therapy didn�t help. Was the problem fluid in her ears, or enlarged adenoids? Willow had her adenoids out the day after she turned 2.
Amber and her husband Tom Cannan probably didn�t know it at the time, but they were about to start the diagnostic odyssey that millions of rare disease families share. It starts with convincing a pediatrician to look beyond the �horses� that are the common childhood conditions to recognize that a child is a zebra or unicorn, with a collection of rare peculiarities that might actually be trumpeting an underlying genetic glitch.
August 31, 2017
Were Ancient Humans Healthier Than Us?
A curious thing happened when researchers at Georgia Tech used modern human genome sequences to look back at the possible health of our long-ago ancestors � they found that while the Neanderthals and Denisovans of 30,000 to 50,000 years ago seemed to have been genetically sicker than us, �recent ancients� from a few thousand years ago may actually have been healthier. Their paper, �The Genomic Health of Ancient Hominins,� is published in Human Biology.
How could that be? Perhaps drugs and procedures that enable us to live with certain conditions also perpetuate gene variants that would otherwise sicken us enough to not reproduce. We pass on those genes and inexorably weaken our global gene pool.
How could that be? Perhaps drugs and procedures that enable us to live with certain conditions also perpetuate gene variants that would otherwise sicken us enough to not reproduce. We pass on those genes and inexorably weaken our global gene pool.
Memo To White Nationalists From a Geneticist: Why White Purity Is A Terrible Idea
In response to media items about white nationalists disappointed in their DNA ancestry testing results, I read the paper on which the reports were based, and wrote "Memo To White Nationalists From A Geneticist: Why White Purity Is A Terrible Idea," for a new website,
Science Trends
. The post is here.
August 4, 2017
Charlie Gard Post-Mortem: Could He Have Been Saved?
Charlie Gard would have turned one year old last week.
Two days before the British infant died of a mitochondrial disease on July 28, a short article in MIT Technology Review teased that Shoukhrat Mtalipov and his team at Oregon Health & Science University and colleagues had used CRISPR-Cas9 to replace a mutation in human embryos, a titillating heads-up that didn�t actually name the gene or disease.
A week later, Nature published details of what the researchers call gene correction, not editing, because it uses natural DNA repair. I covered the news conference, with a bit of perspective, for Genetic Literacy Project and Medscape Medical News .
Might gene editing enable Charlie�s parents, who might themselves develop mild symptoms as they age, to have another child free of the family�s disease? Could anything have saved the baby?
Two days before the British infant died of a mitochondrial disease on July 28, a short article in MIT Technology Review teased that Shoukhrat Mtalipov and his team at Oregon Health & Science University and colleagues had used CRISPR-Cas9 to replace a mutation in human embryos, a titillating heads-up that didn�t actually name the gene or disease.
A week later, Nature published details of what the researchers call gene correction, not editing, because it uses natural DNA repair. I covered the news conference, with a bit of perspective, for Genetic Literacy Project and Medscape Medical News .
Might gene editing enable Charlie�s parents, who might themselves develop mild symptoms as they age, to have another child free of the family�s disease? Could anything have saved the baby?
July 9, 2017
Cystic Fibrosis Among Asians: Why Ethnicity-Based Genetic Testing is Obsolete
A hypothetical heterosexual couple living in the US or UK takes tests to learn if they are carriers of the more prevalent recessive diseases. They�re relieved to find out that cystic fibrosis (CF) isn�t something they need worry about passing to their children � neither has any of the few dozen mutations the test panel includes.
The couple do not carry the most common 32, 106, or even 139 disease-causing mutations in the CFTR gene, the number depending upon the testing lab. But that could be a problem � a false negative � if the woman and man are anything other than non-Hispanic whites.
More than 2,000 variants (alleles) of CFTR are known, and their prevalence varies in different populations. That�s not because DNA recognizes the race or nationality of the person whose cells it�s in, but because of how we choose our partners.
The couple do not carry the most common 32, 106, or even 139 disease-causing mutations in the CFTR gene, the number depending upon the testing lab. But that could be a problem � a false negative � if the woman and man are anything other than non-Hispanic whites.
More than 2,000 variants (alleles) of CFTR are known, and their prevalence varies in different populations. That�s not because DNA recognizes the race or nationality of the person whose cells it�s in, but because of how we choose our partners.
June 30, 2017
Can CRISPR Conquer Huntington�s?
I set a high bar for writing about mouse studies. I don�t include them in my textbooks or news articles, and only rarely blog about them. But when experiments in mice shine a glimmer of hope on a horrific illness with a long history of failed treatments, I pay attention. That happened last week for a report on editing out of mice the human version of the mutant Htt gene that causes Huntington disease (HD), published in the
Journal of Clinical Investigation
.
June 14, 2017
Post-Election Health Effects � Not Just Psychological?
Buried in the lower right corner of last week�s
New England Journal of Medicine
� not up on the left, which spawns the headlines � appears �Health Effects of Dramatic Societal Events � Ramifications of the Recent Presidential Election.� David R. Williams, PhD, MPH, and Morgan M. Medlock, MD, M.Div, both from Harvard, describe �post-election health effects� and list ways clinicians can help their patients cope.
�Health effects,� rather than �syndrome� or �disorder,� suggests that the angst many of us have been feeling since November 9 isn�t a medical condition, but is a strange new normal. Others use stronger terms. Sarah Jones in Politicususa attributes the rape nightmares plaguing many women to Trump Traumatic Stress Disorder (TTSD). John Markowitz�s recent editorial �Anxiety in the Age of Trump� in Comprehensive Psychiatry attributes the �floods of patients� and �national � if not global � rising anxiety� to �Post-Trump Stress Disorder.� I prefer Jones� TTSD, because the distress began well before the shock of the election.
�Health effects,� rather than �syndrome� or �disorder,� suggests that the angst many of us have been feeling since November 9 isn�t a medical condition, but is a strange new normal. Others use stronger terms. Sarah Jones in Politicususa attributes the rape nightmares plaguing many women to Trump Traumatic Stress Disorder (TTSD). John Markowitz�s recent editorial �Anxiety in the Age of Trump� in Comprehensive Psychiatry attributes the �floods of patients� and �national � if not global � rising anxiety� to �Post-Trump Stress Disorder.� I prefer Jones� TTSD, because the distress began well before the shock of the election.
June 13, 2017
Wolf Evolution and "Settled Science"
Are the red and eastern wolves separate species, or hybrids with coyotes? And what has that got to do with climate change? Actually a lot, in illustrating what scientific inquiry is and what it isn�t.
COMPARING CANID GENOMES
A report in this week�s Science Advances questions conclusions of a 2016 comparison of genome sequences from 28 canids. The distinction between �species� and �hybrid� is of practical importance, because the Endangered Species Act circa 1973 doesn�t recognize hybrids. But DNA information can refine species designations � or muddy the waters.
COMPARING CANID GENOMES
A report in this week�s Science Advances questions conclusions of a 2016 comparison of genome sequences from 28 canids. The distinction between �species� and �hybrid� is of practical importance, because the Endangered Species Act circa 1973 doesn�t recognize hybrids. But DNA information can refine species designations � or muddy the waters.
June 2, 2017
Spinach Genome Reveals a Living Fossil
Imagine being spinach.
Sidelined in the produce section of a supermarket, bagged and bunched into a sad uniformity mere feet from the regal, multihued heirloom tomatoes; the purple, orange, and cream-colored cauliflowers; the myriad types of onions, potatoes, squashes and even peas, spinach plants sport a dark green sameness distinguishable only by leaf size.
A WHITER SHADE OF KALE
At farmer�s markets, the lone spinach nestles amongst an ever-growing cornucopia of hipster greens, the kale and arugula, chard and mustard.
Sidelined in the produce section of a supermarket, bagged and bunched into a sad uniformity mere feet from the regal, multihued heirloom tomatoes; the purple, orange, and cream-colored cauliflowers; the myriad types of onions, potatoes, squashes and even peas, spinach plants sport a dark green sameness distinguishable only by leaf size.
A WHITER SHADE OF KALE
At farmer�s markets, the lone spinach nestles amongst an ever-growing cornucopia of hipster greens, the kale and arugula, chard and mustard.
May 29, 2017
5 New Buzzwords Borrowed from Biology
I�ve just finished revising the latest edition of my human genetics textbook, and while checking the glossary, discovered several potential new buzzwords, a few particularly relevant in these strange times.
THE OLD
Co-opting terms from science may have begun with "organic," it�s definition so evolved that I must insert "(carbon-containing)" when I first use the term in a genetics book. Last week for the first time I heard "inorganic," presumably meaning "not genuine."
THE OLD
Co-opting terms from science may have begun with "organic," it�s definition so evolved that I must insert "(carbon-containing)" when I first use the term in a genetics book. Last week for the first time I heard "inorganic," presumably meaning "not genuine."
