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Ricki Lewis

Genetic Linkage

Blinded By Stem Cells

March 19, 2017
Tags: stem cells, age-related macular degeneration, stem cell tourism
Age-related macular degeneration slowly destroys central vision.
The small wavy shimmers and fuzzy areas in the 78-year-old’s eyes had grown slowly, leading to a diagnosis of age-related macular degeneration (AMD), which affects more than 10 million Americans. She had the more common “dry” form. Despite 2 years of injections of one of the latest drugs (a vascular endothelial growth factor [VEGF] blocker), her sight was worsening. How much longer would she be able to drive, with a growing blob obscuring the center of her visual world?

Her family went online to research alternative approaches. Read More 
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Saving GINA: Is Genetic Privacy Imperiled?

March 12, 2017
Tags: genetic privacy
A bill that passed last week in the House threatens genetic privacy protections put in place with the Genetic Information Nondiscrimination Act (GINA) of 2008. The “Preserving Employee Wellness Programs Act” might instead be called the “telling on relatives” ruling.

GINA

According to GINA, employers can’t use genetic information to hire, fire, or promote an employee, or require genetic testing, and health insurers can’t require genetic tests nor use results to deny coverage. The law clearly defines genetic tests – DNA, RNA, chromosomes, proteins, metabolites – and genetic information –genetic test results and family history of a genetic condition.

GINA refers to a case, Norman-Bloodsaw v. Lawrence Berkeley Lab from 1998, that allowed clerical and administrative workers to sue their employer for requiring testing for “highly private and sensitive medical genetic information such as syphilis, sickle cell trait, and pregnancy” without their consent or knowledge during a general employee health exam. I’m not sure how syphilis and pregnancy got lumped in with sickle cell trait (a carrier), but requiring any such test is considered an illegal search under the Fourth Amendment. The sickle cell request also violates Title VII of the Civil Rights Act by singling out employees of African ancestry. Read More 
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Is Transgender Identity Inherited?

March 5, 2017
Tags: transgender, genetics of transgender
The recent return of the "which bathroom?" issue regarding transgender individuals’ use of public restrooms has made me think about how I’ve handled sex and gender in my human genetics textbook. Over the editions, the two topics have diverged. And that’s at the crux of misunderstanding. Read More 
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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. Read More 
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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. Read More 
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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. Read More 
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12 Alternative Facts of Human Genetics

January 28, 2017
Tags: alternative facts, Kellyanne Conway, history of genetics, Mendel, Griffith
I’ve always wanted to write about my favorite experiment in human genetics, but a news hook was elusive. Not any more! Thank you Kellyanne Conway for your intriguing concept of "alternative facts."

I’m writing the 12th edition of my human genetics textbook right now, so it’s the perfect time to browse through the pages and select a few turning points in time when genetic reality might have diverged, leading to different outcomes, if "alternative facts" were possible. But first, to illustrate how scientists reject hypotheses to reach a conclusion, a brief review of what’s been called "The Most Beautiful Experiment in Biology".  Read More 
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A Necessary Retelling of the Smallpox Vaccine Story

January 17, 2017
Tags: vaccine, smallpox, Edward Jenner, Donald Trump, RFK Jr, Autism, anti-vaxxer
People once feared that small cows would emerge from the arms of vaccinated people. Ignorance about vaccines persists.
A curious confluence of events unfolded January 10. Just hours before President Obama uttered the powerful “science and reason matter” in his farewell address, Robert F. Kennedy Jr. announced that the incoming president had tapped him to head a committee on vaccine safety.

RFK Jr. is not a pediatric immunologist nor an epidemiologist, but a vocal "vaccine skeptic". Although the PEOTUS dialed back on the purported appointment shortly after social media erupted, a tweet from March 28, 2014 clarifies the new president’s analysis of the history and science of vaccines:

Healthy young child goes to doctor, gets pumped with massive shot of many vaccines, doesn’t feel good and changes – AUTISM. Many such cases!  Read More 
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Gene Action Tracks an Autoimmune Disease: Systemic Sclerosis

January 5, 2017
Tags: systemic sclerosis, scleroderma
Systemic sclerosis (Ssc) is a rare disease in which collagen gloms up internal organs and toughens the skin into an armor of sorts. It's also called scleroderma, from the Greek for “hard” (skleros) and “skin” (derma). Ssc is autoimmune, not inherited, but a recent report in JCI Insight describes how gene expression profiling -- transcriptomics – can add precision to diagnosis, monitor response to treatment, and identify drugs that might be repurposed to target SSc.  Read More 
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Genetics Error in "The Man in the High Castle" Season 2?

January 4, 2017
Tags: The Man in the High Castle
What if the Germans and Japanese had won WW2?
I’ve just finished watching season 2 of Amazon video’s terrifying The Man in the High Castle, which depicts an alternate reality in which Germany and Japan won the second world war, with an atomic bomb taking out Washington, DC. I admit confusion over gaping plot holes and teasers, but I did catch enough of the dialog to suspect that genetic info about one of the families is wrong.

Thomas Smith, adolescent son of Obergruppenführer John Smith, has a form of muscular dystrophy. According to a footnote in Wikipedia, it is Landouzy-Dejerine syndrome, which I hadn’t heard of by that name but recognized its name today, facioscapulohumeral muscular dystrophy (FSHD). It is autosomal dominant – if you have it, so does or did one of your parents, unless you're a new mutation (about 30 percent of cases).

In a 10-second scene in the final episode, we learn that John Smith’s uncle had the disease, and that his two daughters must be carriers.

Well, no.

A dominant condition doesn’t have carriers. You have the mutation or you don't, although symptoms may occur later in life, in which case a person with the mutation is pre-manifest, not a carrier in the classic sense. Since Tom’s uncle had it too, presumably before the State murdered him, and the condition is rare, it must be inherited, not due to a new mutation. I can only reconcile these facts if John Smith has the mutation too but is non-penetrant – meaning he has the genotype but not the phenotype. I wonder what the Nazis, obsessed with purifying the gene pool, would do with that intel! Plus, Thomas has what appears to be seizures and he trips – not the upper body weakness of the disease.

I suppose the writers chose FSHD because it isn’t horrible, making it more horrible that the Nazis exterminate those who have it. When Thomas realizes that he’s not healthy, he mutters the mantras “I’m a useless eater” and “I'm defective.”

I won’t spoil the ending. But can anyone explain an inheritance pattern that has carriers and non-penetrance? Meanwhile, maybe the new showrunner for season 3 will take a genetics course. Read More 
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