Ricki Lewis

The once-prevailing concept of a sole "gay gene" dictating sexual orientation has been put to rest in a powerhouse study published in Science. The work illustrates the nature of science: evolving with the input of new data, especially the large-scale contributions of bioinformatics and crowd-sourcing.

"We formed a large international consortium and collected data for more than 500,000 people, comparing DNA and self-reported sexual behavior. This is approximately 100 times bigger than any previous study on this topic," said lead author Andrea Ganna, of the Institute of Molecular Medicine in Finland and an instructor at Massachusetts General Hospital and Harvard Medical School, opening a news conference earlier this week.

Human Sexuality is Nuanced and Complex

The investigation lowers the estimate of the genetic contribution to same-sex sexual behavior, thanks to analysis of a trove of data from the UK Biobank and the consumer genetic testing company 23andme.

I hope that the demonstration of a diminished role for genetics will counter the idea that having sex with a person of the same sex is something biologically broken that needs to be fixed. "Using these results for prediction, intervention, or a supposed 'cure' is wholly and unreservedly impossible," points out Melinda Mills, a sociologist from the University of Oxford in an accompanying Perspective.

To continue reading go to my DNA Science blog at Public Library of Congress, where this post first appeared.

A small group of scientists, regulators, business people and patient advocates met recently at the National Academy of Sciences in Washington, D.C., to discuss the path forward in using genome editing tools, like CRISPR, to modify the human germline – that is, eggs, sperm or fertilized eggs. Such a change is heritable, passed to future generations.

It was the inaugural meeting of the International Commission on the Clinical Use of Human Germline Genome Editing. The tone during the day [August 13] was considerably more measured than the media splash that Victoria Gray, a 34-year-old from Mississippi with severe sickle cell disease, had made a few weeks earlier.

She's the first person to undergo a treatment using CRISPR, but the clinical trial she's in, sponsored by Vertex Pharmaceuticals, targets only cells that give rise to red blood cells, which shed their DNA as they mature. Victoria is the first of 45 patients expected to enroll, with results in summer 2022.

Altering the germline is a different story.

To continue reading, go to Genetic Literacy Project, where this post first appeared.

Today [August 13] the US National Academy of Sciences is hosting the first meeting of the International Commission on the Clinical Use of Human Germline Genome Editing in Washington, to discuss controversial applications of CRISPR to human eggs, sperm, or fertilized ova, in the wake of Chinese researcher He Jiankui announcing the birth of CRISPR twins after a similar meeting in 2017 (See Do China's controversial CRISPR babies illustrate the need for an undo button?).

Although only one clinical trial is up-and-running for CRISPR to treat body cells, with an initial patient making the media rounds just last week to discuss her cells doctored to counter sickle cell disease, many other applications are in preclinical testing — animal models and human cells and organoids. And they're not restricted to rare diseases.

Imagine a single injection that quells the inflammation behind lower back pain — perhaps forever. CRISPR may make that possible by dampening the immune system's cytokine signals, according to a report in the July issue of Human Gene Therapy.

To continue reading, go to Genetic Literacy Project, where this post first appeared.

When the name Kary Mullis popped up in my news feed on Monday, I was excited to read what I thought would be an update on the renegade inventor I'd met years ago at a small biotech gathering in San Diego. Back then, in the late 1980s, I'd interviewed him for Genetic Engineering News, where I had the gene amplification beat – a field that began with the polymerase chain reaction, aka PCR.

An Eclectic Technology

Kary Mullis died on Monday, August 12, of heart disease and respiratory failure. He was so quirky that obituaries, like the one in the LA Times, led off with such descriptors as "LSD-dropping, climate-change-denying, astrology-believing, board surfing." That obit calls PCR a "discovery." But the technology wasn't laying around waiting for someone to find it, like an ancient skull. Instead, it was an invention deduced from the scrutinizing the mechanics of DNA replication.

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

Exercise is a key component of any weight-loss plan, but it's especially important for people who've inherited a tendency to easily put on pounds. Results of a study published in the August issue of PLOS Genetics adds some granularity to that maxim, parsing 18 activities by their effect on the inherited risk of obesity.

Six activities come out on top, with the winner what the researchers call "regular jogging." 

To continue reading, go to my DNA Science blog at Public Library of Science, where this post originally appeared. 

When rocker Tom Petty sang "the waiting is the hardest part," he wasn't referring to genetic testing for breast cancer. But he could have been.

After the pathology report from a breast biopsy brings bad news, the next step is often a blood test for risk mutations, probing dozens of genes. Because that information guides the course of treatment, waiting for the findings can send one's stress level through the roof. I've been there.

If a mutation is found, removing the unaffected breast suddenly becomes an option, for it may already be on the road to cancer. Alerting children, siblings, cousins, and nieces and nephews to a familial risk may be appropriate.

Mutations interfere with natural DNA repair, which allows other mutations to persist that release the normal brakes on cell division. By the time a cancer has been around awhile, the errant cells are riddled with mutations.

But mutations in the DNA of white blood cells reflect only the 5 to 10 percent of cancers that are inherited — that is, present in the DNA of every cell of the body and dubbed "germline." The majority of cancers start in body (aka somatic) cells; they don't come in with a sperm or egg, but spring up in cells of the affected body part.

Most cancers are genetic but not inherited

I'm in several Facebook groups for breast cancer survivors. Every few days, someone posts a variation on "My genetic tests are negative. I have no family history, I'm thin, I do triathlons, I'm vegan and don't smoke or drink. So why do I have breast cancer?"

To continue reading, go to Genetic Literacy Project, where this post first appeared.

CRISPR continues to be big news.

Condemnation of the gene editing technology was swift late last year when a researcher in China claimed to have used it to doctor the genomes of twin girls to enable them to resist HIV infection.

Agricultural and future medical applications of CRISPR continue to inspire debate, while the idea of gene drives to fuel extinctions of disease vectors, like mosquitoes, raises concern over the danger of tinkering too much with ecosystems.

CRISPR has entered fiction plots, such as last spring's ridiculous Rampage. The just-axed Netflix reboot of Designated Survivor transformed the acronym into a verb, as in "the bird flu gene was CRISPRed into the virus." Makes me think of biotech bacon.

Although curing disease, wiping out mosquitoes, and creating fictional bioweapons are exciting prospects, I'm more interested in the harnessing of CRISPR to peek at the origins of disease, in cells. Hollis Cline, PhD, and her colleagues at the Scripps Research Institute have done just that to investigate Rett syndrome, reporting in the Proceedings of the National Academy of Sciences.

A Neurological Syndrome 

Rett Syndrome affects 1 in every 10,000-15,000 girls, and very rarely boys. The son of NBC news correspondent Richard Engel is an exception; he has a mild mutation. The condition typically arises as a new, dominant mutation on the X chromosome in a gene called MECP2.

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

Eating just 50 bitter almonds can release enough hydrogen cyanide to kill an adult in under 3 minutes. Fortunately, the sweet variety that we scoop from bins at grocery stores is safe to eat, thanks to a mutation.

While the single-gene glitch behind almond palatability has been recognized for a century, it took genome sequencing to reveal the complex control of the trait. Raquel Sánchez-Pérez, a biochemist at CEBAS-CSIC, an agricultural research center in Spain, and colleagues at the University of Copenhagen and elsewhere in Europe, published their findings in Science in June.

A Beloved Nut Through History

Almonds lead pistachios, brazil nuts, walnuts, pecans, cashews, and pine nuts in tree nut popularity, with peanuts the most popular groundnut.

In 2016 Michelle Obama joked that her husband consumes exactly 7 almonds every night. "That's it!" she exclaimed. When The New York Times reported the observation seriously, eating 7 almonds became a thing.

Headlines shout the attributes. "9 Evidence-Based Health Benefits of Almonds" lists vitamins, minerals, and anti-oxidants, crediting the nuts with lowering blood sugar, cholesterol, and hunger. So many articles tout the ability of almonds to "melt away body fat" that, well, it must be true.

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

My writing assignments for Medscape Medical News tend to be formulaic: summarize the findings of an interesting new paper, enabling busy health care professionals to stay on top of the literature. I knew immediately the importance of an assignment from a few weeks ago – a team from the University of British Columbia had found a way to convert type A blood to type O. The report, in Nature Microbiology, details how they commandeered a pair of enzymes from a human gut bacterium.

That's huge.

Type O blood is the "universal donor." An individual of any ABO blood type can receive it without suffering a rejection reaction, until supplies of the matched type become available. That's because the surfaces of red blood cells (RBCs) that are type O lack certain glycoprotein molecules that festoon cells of types A, B, or AB.

Because more people have type O blood (45%), finding a way to make more of it could help address the ongoing shortage of human blood. The American Red Cross recently began offering gift cards to entice type O donors, warning that unless supplies extend from 2-days to 5-days, some emergency departments will be without blood and some types of surgeries delayed.

I guessed that the researchers had found some way to denude types A, B, or AB RBCs – shake them, zap them, bathe them in enzymes – but I didn't imagine that beaver dams would be an inspiration. My Medscape article had only a sentence on the beaver connection, so I thought I'd elaborate here at DNA Science, where inquiring minds gravitate to the weird.

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

Is your body wash gentle on your microbiome? asks the voiceover in a Dove ad.

A half dozen befuddled young women then attempt the Herculean task of repeating the word "microbiome." Finally, one says, "I actually don't even know what that is!"

MotherDirt Body Wash has "been screened and tested using our biome-friendly platform for compatibility with the skin's natural biome," reads the label. Sounds good! But a closer look reveals it's liquid soap with a pinch of salt, a dash of sweet almond oil, citric acid, and, of course (?), some hydrolyzed pea protein.

Popularity of "microbiome"-as-buzzword must have presented an advertising challenge for a body wash, which must remove dirt but not unsettle the microbial residents of the human epidermis. And so the products promise to maintain the skin microbiome, as if it's going to spontaneously evaporate unless one forks over $30 for a bottle of soap.

To continue reading, go to Genetic Literacy Project, where this post first appeared.