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Genetic Linkage

How the Pangolin Got Its Scales – A Genetic Just-So Story

Everyone loves animal oddities.

Darwin and Lamarck pondered the advantages of the giraffe’s long legs and neck, while a few decades later Rudyard Kipling explained how the leopard got its spots. Today genome sequencing is fleshing out what we thought we knew about some distinctive animal adaptations, from the giraffe to the leopard.

Adaptations are inherited traits that increase the likelihood of an individual surviving to reproduce. A zebra's stripes rendering it invisible when it runs and the fennec fox's giant ears that dissipate heat and hear distant predators are adaptations.

A report in this month’s Genome Research provides the basis for a “just-so story” about how the pangolin – aka the scaly anteater -- got its scales. They protect, but in a way beyond the obvious. According to the genome, the armor of the pangolin replaced part of its immune response.
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Genetic Modifiers: Healthy Mutants Fuel Drug Discovery

Disease-causing mutations in healthy people suggest new drug targets. (NHGRI)
I’m uneasy counseling a patient for mutations in the BRCA1 or BRCA2 cancer susceptibility genes. Typically, she’ll have a “first degree relative” – usually a mother or sister – with a related cancer, or might even have a test result in hand. This happened a week ago.

FUZZY GENETIC INFORMATION
My patient comes from a long line of female relatives who’d died young from breast or ovarian cancer. She’s already been tested and knows she has a BRCA1 mutation. Will she get the family’s cancer? Knowing would enable her to decide whether and when to undergo surgery to remove her breasts, ovaries, and uterus. Read More 
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Incidental Findings from Genome Sequencing – Nuances and Caveats

A genome sequenced to investigate one disease may reveal another.
You have your genome or exome (the protein-encoding part) sequenced to help diagnose a puzzling set of symptoms, and something totally unrelated, and unexpected, turns up – a so-called “incidental finding.”

Surprises, of course, aren’t new in medicine. The term “incidental finding” comes from “incidentaloma,” coined in 1995 to describe an adrenal tumor found on a scan looking for something else. I had one -- a CT scan of my appendix revealed a polycystic liver. A friend had it much worse. She volunteered to be a control in an Alzheimer’s imaging trial, and her scan revealed two brain aneurysms!

Geneticists have long expected an avalanche of incidental findings from clinical (exome or genome) sequencing. Read More 
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Genetic Testing: Carrier Confusion & Generation Reversal

A breast cancer cell. (Natl Cancer Inst)
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. Read More 
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Why I Don't Want to Know My Genome Sequence

Even after writing 10 editions of a human genetics textbook, I don't want to know my genome sequence. Yet.
Famous folk have been writing about their genome sequences for a few years now. But when I received two such reports at once last week – about genetics researcher Ron Crystal, MD, and a hypothetical (I think) story about President Obama, I knew it was time to take action.

Or, in my case, inaction. Read More 
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Like a Game of “Clue,” Genomics Tracks Outbreak, Revealing Evolution in Action

Genome sequencing traced a deadly bacterial outbreak at the NIH Clinical Center in June 2011.
Was it Colonel Mustard in the library with a lead pipe? Or Mrs. Peacock in the ballroom with a candlestick? No, it was deadly, drug-resistant Klebsiella pneumoniae from a 43-year-old woman spreading to 17 other patients, killing 6 of them and sickening 5 others, at the National Institutes of Health’s (NIH) Clinical Center in June 2011.

In  Read More 
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The Bonobo Genome, Dave Matthews, and Rewinding the Tape of Life

Ulindi, a bonobo, has had her genome sequenced. Photo courtesy Max Plank Institute for Evolutionary Anthropology
When I wrote for The Scientist, I covered the debuts of several genome sequences – fruit fly, rat, pufferfish, and the plague bacterium, to name a few. An illustration in my human genetics textbook resembles the intro to The Brady Bunch, a checkerboard of nine new genomes with each edition, now with more than 1,000 to choose from. In just the past few weeks, several salad ingredients have had their genomes unveiled.

But the genome sequence to intrigue me the most, except for our own, is that of the bonobo, aka Pan paniscus.  Read More 
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My Microbiome

My Microbiome

Yesterday I committed a terrible crime. I walked away from a treadmill at the Y without scrubbing the handles.

“Ricki, get back here,” admonished the attendant as I headed for the elliptical. “You forgot to wipe down!”

“But I’m not sweating, and I never get sick. I won’t pass along  Read More 
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Creating Life and Curing Blindness

I’ve been at the American Society of Gene and Cell Therapy annual meeting this week, garnering tales for my book, tentatively entitled “The Forever Fix.” It is largely the story of 9-year-old Corey Haas, who was on his way to certain blindness when gene therapy performed at the Children's Hospital of Philadelphia in September 2008  Read More 
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