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Genetic Linkage

Unveiling the genome of the ancient dingo — whose DNA is in every dog in the world

Maybe a dingo ate your baby!" suggested Elaine Benis (Julia Louis Dreyfus) in an episode of Seinfeld in season 3, bumped from season 2 because Larry David thought it not very good. But the phrase stuck. 
Elaine's literary quote harkens back to a 1998 Meryl Streep film, A Cry in the Dark. Streep played Lindy Chamberlain-Creighton, who utters some version of "the dingo's got my baby!" after her nine-week-old daughter Azaria was taken from the tent that she and her then-husband Michael Chamberlain were sharing while camping in the Northern Territory, Australia.
The film was based on a true story, a tragedy that happened on August 17, 1980. Lindy was convicted of murder and given life in prison while Michael was considered an accessory after the fact and given an 18-month suspended sentence. But legal challenges eventually exonerated both parents. A coroner eventually attributed the baby's disappearance to "the result of being attacked and taken by a dingo." So, it happens.
To continue reading, please go to Genetic Literacy Project, where this post first appeared.
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Probing the Genomes of the Roma, the Forgotten Europeans

The Roma people have long held a special fascination for population geneticists who study the frequencies of genetic diseases. The largest minority in Europe, the Roma number 10 to 12 million and live in scattered groups, mostly in central and southeastern Europe. A recent Comment in Nature, from a team at the University of Freiburg, explores how "Europe's Roma people are vulnerable to poor practice in genetics."


A Tragic History


The Roma, once called gypsies, likely originated in the Punjab region of northwest India about 1,500 years ago. They traveled to Persia (Iran), then through Armenia to the Balkan peninsula, and reached the Iberian peninsula by the 15th century. Their genomes diversified as people joined along the way. After their arrival in Portugal and Spain, persecution began. It was the beginning of extreme discrimination and isolation that would unfold over the years.


The Roma and the Jews became the targets of the Nazi goal of "racial hygiene." In 1936, investigators at The Race Hygiene and Population Biology Research Centre drew pedigrees of these groups to form the rationale of a "scientific basis" for the "final solution." German geneticists studied the Roma. Ferdinand Sauerbruch, nominated for a Nobel, submitted a grant proposal to conduct "genetic and medical research" in Auschwitz, which the Deutsche Forschungsgemeinschaft funded. Hundreds of thousands of Roma died in experiments.

To continue reading, go to DNA Science, where this post was first published.

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A Glimpse at a Future Heart Disease Drug Thanks to Gene Silencing

I often marvel at the disconnect between media coverage of "breakthrough" treatments and the decades of research that lie behind them. A new drug is the culmination of basic research, preclinical experiments on animals and cells, three phases of clinical trials, and post-marketing surveillance. It takes decades.


A small, phase 1 study – safety in healthy people – caught my attention this week. The work was presented at the American College of Cardiology's annual meeting and published online in the Journal of the American Medical Association.


The healthy participants had elevated levels of apolipoprotein(a), which is made in the liver and goes to the blood, where it carries cholesterol. High levels raise risk of heart attack, stroke, and narrowing of the aorta. Could silencing the gene that encodes the protein portion of apolipoprotein(a) lower the level, perhaps even preventing the heart disease?


One way to silence a gene uses a natural process, RNA interference (RNAi), which blocks translation of a gene's information into construction of a specific protein. The first drug using RNAi was Onpattro, approved in 2018 to treat a rare form of amyloidosis. The disease causes tingling, tickling, and burning sensations and affects about 3,000 people in the US.


In the new study, the researchers injected tiny pieces of short interfering RNAs (siRNAs), which glommed onto the messenger RNAs for the protein part of apolipoprotein(a). The 32 healthy volunteers received placebo or ascending doses. Levels of apolipoprotein(a) fell in a dose-dependent manner, by about 98 percent for the highest-dose group. All doses were well tolerated and the lowering largely persisted when checked at five months.


To continue reading, go to my blog, DNA Science, at Public Library of Science.

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How to Make an Allergen-Free Cat, Using CRISPR Gene Editing

I pity the 15 percent of the human population that cannot live with a cat, due to allergy. I've seen it happen, a guest's face blowing up. My best friend Wendy can visit here, where cats outnumber people two-to-one, only by megadosing on antihistamines and heading to the porch to breathe periodically. Even with that she's good for only a day or two.


But CRISPR gene editing may come to the rescue, someday.


Snip out the gene that encodes a protein called Fel d 1, and the kitty can no longer make a hapless human's eyes and nose run and bronchioles constrict in an asthma attack. That's what Nicole F. Brackett and a team from InBio have done in cat cells. Their work was just published in The CRISPR Journal. (If googling makes this news seems recycled, it's because an abstract appeared just before the world shut down in early 2020.)


CRISPR is a tool that can remove, replace, or add a selected bit of DNA to a chromosome. To counter cat allergy, CRISPR would delete the genes that encode the offending allergen.


To continue reading, go to my blog DNA Science, where this post first appeared.

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