Ricki Lewis

When NASA reported preliminary observations about the famous "twin astronaut" study a year ago, the media rushed in, reporting the effort with mind-boggling inaccuracy. The agency was quick to correct the confusion of gene mutations with changes in gene expression, promising a full paper once the findings were more fully scrutinized. Long-awaited, "The NASA Twins Study: A multidimensional analysis of a year-long human spaceflight," appears in the April 11 issue of Science.

To recap, Scott Kelly (Space Twin) spent a year aboard the International Space Station (ISS) while his identical twin Mark (Earth Twin) stayed in Arizona. Both men are 50 years old. Mark, also an astronaut, is married to Gabrielle Giffords and is running for the Senate in 2020.

A data deluge

With last year's overreaction, it's understandable that announcement of the full paper to reporters ahead of publication set the stage for a news blitz. The four press releases, images and videos, a list of quotes from NASA scientists, phone news conferences from Science and NASA, a summary, web materials, and a short feature article in Science sent my hype-o-meter into overdrive.

Much of the news isn't news – Genetic Literacy Project covered it a year ago. Plus, many of the monitored biological functions didn't change much in space or did so only transiently.

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

As drugstore chains embrace products with traces of CBD, two recent reports in prominent medical journals point out the dangers of the other familiar component of cannabis, THC.

An article in Lancet Psychiatry strengthens the link of THC to psychosis, and one in Annals of Internal Medicine chronicles people ending up in the emergency departments of hospitals after indulging in edibles. The news media picked up the edible-ED story, the psychosis one not so much.

From 2012 through 2016, the University of Colorado Hospital saw a more than 3-fold increase in cannabis-associated ED visits. Edibles, which became available there in 2014, were disproportionately represented in those visits – 10.7 percent due to edibles, despite making up only 0.32 percent of total cannabis sales.

I can relate.

A short, strange trip

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

"Do you mind if we take one more sample?" asked the endocrinologist who had already stuck six needles into the bulge in my neck that would turn out to be thyroid cancer. "It's for a research study."

"On what?"

"Something called p53."

That's a tumor suppressor, a gene that lies at the crux of cancers triggered by environmental factors, like the 5 years of unprotected dental x-rays I'd had as a kid.

"I know what that is and hope I don't have a mutation. When will I get the results?"

"I'm afraid you won't. That's part of the protocol." My sample would be de-identified.

I forgot about it. Years later, I had genetic testing again, this time for breast cancer, from a blood sample sent to Invitae, a clinical testing lab. They applied their 80-gene cancer panel and threw in probes for another two dozen genes they were developing.

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

I'll admit that I have long admired the beauty of the large milkweed bug Oncopeltus fasciatus, without knowing anything about it. So I was pleased to read of the recent publication of its genome sequence, an effort undertaken by 83 researchers working as 27 teams in 10 nations. The findings are reported in Genome Biology.

Most of the 100+ insect species that have had their genomes sequenced are homometabolous, which means that they develop through several stages of larvae, metamorphose, and then burst from their cocoons looking completely different. (See "The Making of a Mutant" for a scintillating view of fruit fly larvae living in goop in a milk bottle.) Flies, beetles, wasps, and butterflies are among the homometabolous.

In contrast, milkweed bugs are hemimetabolous. The species of this group are less well represented among the sequenced, although they are more numerous. The juvenile stages of milkweed bugs are tiny, flightless versions of the adults, called nymphs, that have more orange.

The hemimetabolous insects have trademark mouthparts that pierce and suck, and include agricultural pests and vectors of human disease, like the kissing bugs that deliver Trypanosoma cruzi, the cause of Chagas' disease. A more familiar hemimetabolous insect is the bed bug Cimex lectularius.

The milkweed bug, so-named because it eats the bitter seeds of the milkweed plant Asclepias syriaca, joins many other insects and their arthropod cousins in having their genetic selves laid bare as part of the i5k project. The international consortium is sequencing the genomes of 5,000 arthropod species.

So far partial or complete genomes have been unveiled for, in alphabetical order, ants, aphids, bedbugs, bees, beetles, borers, cockroaches, crabs, crayfish, fleas, flies, lice, locusts, mealybugs, midges, mites, mosquitoes, pillbugs, psyllids, scorpions, shrimp, spiders, stinkbugs, ticks, wasps, weevils, worms, the delightful-sounding snowberry maggot and meadow spittlebug, and a pretty butterfly called a Glanville fritillary.

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

I've just had cataract surgeries, so I wasn't thrilled to find a new report in the Proceedings of the National Academy of Sciences comparing the protein glitch behind them to the one behind Alzheimer's. Fortunately the similarity is only in how the proteins fold.

The amyloid beta buildup of cataracts could be an early marker that might eventually allow drug treatment to replace surgery. Too late for me, but that could be great news for the more than 18 million people worldwide  blinded by cataracts because they can't get surgery.

Cataracts develop as proteins coalesce in the lens, triggering spreading of patches of blurriness. They are the leading cause of blindness globally and affect half of people over age 50. My fellow PLOS blogger Hilda Bastian recently recounted the compelling story of the origin of cataract surgery.

A human lens is fascinating, in terms of biochemistry, cell biology, and evolution.

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

Chronological aging is easy to track – birthdays. Biological aging can be obvious too – graying hair, sagging skin, and other inexorable signs of impending decrepitude. But measuring biological aging isn't as easy as noting the passage of time.

The best-studied measure of biological age is the shrinking of chromosome tips, or telomeres, that do so with each division of most types of cells. As soon as I posted "Telomere Testing: Science or Snake Oil?" here at DNA Science, my Facebook feed filled with ads from companies like this one, offering to enlighten me on the status of my chromosome tips.

The new biological ticker, the rDNA clock, makes its debut in the latest issue of Genome Research. Meng Wang and Bernardo Lemos, from the Harvard T.H. Chan School of Public Health, term rDNA a "universally applicable marker of aging." Their article also is a brilliant example of how science is done, with a series of hypotheses and experiments, countering the oft-bellowed mantra that one can "believe in" climate change, evolution, or cell structure.

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

A commentary published today in the journal Cell offers evidence of a stunning imbalance in the population groups that participate in genetic and genomic research, which can underlie some health care inequities. A glance at the pie chart below, which represents many genome-wide association studies (GWAS), reveals a telling tipping in favor of participants of European ancestry – 78 percent. Asians account for just 10 percent, and Africans 2 percent.

A GWAS is a sweeping look at single sites (SNPs) among a genome's 3.2 billion bases that differ among people. It's used to trace traits and conditions caused by multiple genes plus environmental influences. Algorithms deduce the associations from SNP data from people who share ancestry as well as a trait or disease of interest. "Ancestry" means shared heritage, manifest as hunks of genomes, and not what a sociologist might call race based on appearance.

The Eurocentric nature of the pretty pie charts and polygons of consumer ancestry tests of course reflect the market. The skewed representation in company databases can lead to surprise, confusion, and disappointment, when a population simply isn't yet on the radar.

In clinical studies, the stakes are higher. The overrepresentation of European whites can lead to sub-optimal diagnoses and therapeutic choices for people in other population groups. That's what prompted the commentary in Cell, "The Missing Diversity in Human Genetic Studies," from Giorgio Sirugo and Sarah Tishkoff from the University of Pennsylvania and Scott Williams of Case Western Reserve University. Citing examples from the long-studied single-gene conditions and others, they compellingly convey the importance of considering genetic ancestry in health care.

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

We don't usually pay attention to how we position our teeth when biting into a tough steak or ripping soft kernels off a cob of corn. But a team of linguists has just reported in Science on their "biomechanical simulations of different human orofacial structures" to test the hypothesis that changes in dentition that accompanied a switch from a hunter-gatherer lifestyle to an agricultural one may have, perhaps accidentally, brought about the ability to pronounce "f" and "v" sounds.

These utterances that require the upper teeth to extend over the lower lip are called "labiodental sounds." They're harder to make than just extending the upper lip over the lower to produce "m," "w," and "p" sounds, which are common in many languages.

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

I'm a curious hybrid, a geneticist and an "NPE" – "not parent expected" – individual. My few posts about it, such as here and here, were from January, when I thought I had only one half-sibling. The discovery of others, some of whom know they were donor-conceived (DC), more or less confirms half of my origin.

So I wondered, on what percentage of a human genome's 3.2 billion DNA bases do the consumer DNA ancestry companies base these deductions that can shatter lives?

Do some tube-spitters and cheek-swabbers assume entire genomes are compared? No, not for $100, just yet. Others might not know what SNPs are, the  single-DNA-base markers that align in haplotypes on chromosomes and are used to match people, the algorithms trained on known relationships. With millions of people taking ancestry tests, the associations used in the matches are quite robust.

But I thought I'd do a small calculation to clarify what's probed when you plop your genetic essence into the mail, and how it represents an individual.

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

For 2019's Rare Disease Day, DNA Science honors those who have fragile X syndrome (FXS). It isn't among the rarest of the rare, yet when health care providers can't assemble the diagnostic puzzle pieces that parents are practically yelling at them, the statistics don't matter and the diagnostic odyssey lengthens. Because fragile X is an "expanding repeat" disorder, it lies beneath the radar of standard chromosome and single-gene tests.

The Orphan Drug Act of 1983 in the US defined a rare disease as affecting fewer than 200,000 people. "Orphan" initially referred to pharma's disinterest in developing drugs with minuscule markets, but was deemed non-PC and became "rare" somewhere along the way. In the European Union, the definition is fewer than 1 in 2,000 people, which is pretty close to the US number. The disinterest in seeking treatments for ultrarare conditions has evolved into doing so, but with sky-high price tags.

A few weeks ago I heard from Desiree Moffitt, who uses my human genetics textbook to teach an online course. She kindly offered to share her family's story about life with a child who has fragile X syndrome. "Usually the face of disability is a very happy, quirky family. While we are happy and also quirky, our story isn't as fun," she emailed me. First, some background on fragile X.

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