Ricki Lewis

Last year, nine-month-old KJ Muldoon made history when a variation of CRISPR gene editing, called base editing, swapped one DNA building block for another at a specific part of his mutant gene. He had inherited a urea cycle disorder called carbamoyl-phosphate synthetase 1 (CPS1) deficiency. It hampers the ability to digest protein and is among the rarest of the rare, affecting only about one in 800,000 to one in 1.2 million newborns, in different populations.

The boy had inherited one mutation from each parent; they are unaffected carriers. His liver couldn't produce the crucial enzyme CPS1, and as a result, ammonia released from the breakdown of the amino acids in dietary proteins was accumulating in his bloodstream. Organ failure and, ultimately, brain swelling and coma would follow. Half of the babies with the condition do not survive infancy.

KJ's case was reported in The New England Journal of Medicine May 15 of last year, "Patient-Specific In Vivo Gene Editing to Treat a Rare Genetic Disease." DNA Science covered it here.

More recently, KJ appeared at a news conference March 2, 2026, to celebrate Rare Disease Day. The toddler demonstrated his ability to walk. He has very mild symptoms of the ultrarare disease.

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

Organoids are tiny bits of organs nurtured in lab glassware from stem cells. I joke about them at Halloween, when a few drops of water on tiny sponge brain and heart precursors bloom into mini-organs.

A Bridge Between Animal Models and Clinical Testing

Real organoids are a brilliant tool to investigate biological processes and test new treatments. Induced pluripotent stem (iPS) cells are grown from a patient's skin fibroblast cells, providing a platform to test individualized interventions. And iPS cells are much closer to the human condition than a fruit fly, worm, zebrafish, rodent, or even a primate model.

Organoids aren't complete replicas of organs, but mimic how cells assemble into tissues of a specific organ, and how those tissues interact. They offer an increasingly important step between testing a treatment in an animal model and in people in clinical trials, saving time and funding and improving safety and efficacy.

The most recent report of a novel organoid to capture my attention is a mini human spinal cord, which researchers at Northwestern University created to model different types of injuries to test regenerative treatments. Like a spinal cord in a body, these miniature bits of humanity display inflammation, cell death, and the clumping of glial cells into impenetrable scar-like masses that can squelch nerve healing and regeneration.

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

I have a curious relationship with AI.

A few years ago, I began to notice that when I posed a query on a topic in genetics – for a DNA Science post or to update my textbook Human Genetics: Concepts and Applications with McGraw-Hill – an answer would pop back that read curiously like my own words. Likely, they were.

So I wasn't terribly surprised when, a few months ago, a notice appeared in The New York Times and elsewhere: "Anthropic to pay authors $1.5 billion" in a class action lawsuit brought by three authors. Fourteen of the half million "works" that the company copied, to train its chatbot Claude, were mine!

AI Saves Time, Provides Details

Right now, I'm working on the next incarnation of my textbook. Editions are outdated, I'm told, so this is a revision – not much of a difference. To update in this age of AI, I still scrutinize new research findings, led to journal articles through old school press releases in my email.

But AI is becoming increasingly helpful in handling the minutiae, of quickly updating a statistic or other detail. What does screening the genome of an early embryo cell cost? How are cancer immunotherapies selected for a particular patient? Which single-gene diseases are amenable to correction using CRISPR?

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

Links between environmental exposures and increases in cancer rates take time to emerge. They range from community-wide disasters, like the 25-year dumping of carcinogens into the former Love Canal in Niagara Falls that caused kidney and bladder cancer, to associations that seem obvious in retrospect, like smoking and lung cancer, sun exposure and melanoma. My breast cancer might have arisen from in utero exposure to diethylstilbestrol (DES), a drug given to pregnant women in the 1950s to calm morning sickness.

The hallmark of an environmentally-triggered cancer is a sudden increase in incidence (rate of new cases over time) and prevalence (total cases at a specific time) of a particular type of cancer that parallels an increase in exposure to a specific chemical, or class of chemicals. A genetic change would take much longer to manifest.

A classic illustration of an environmentally-caused cancer is the increase in lung cancer in the 1950s that followed the pervasive cigarette smoking among the post-World-War-II generation. It was a time when cigarette ads dominated TV, airplanes stunk of stale smoke, and the habit was actually considered attractive. Many people, especially women, felt pressured to smoke to be accepted.

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

I fear that 2025 is ending with a tragic irony: the dismantling of progress in biomedical research, as infectious diseases return and resurge. Arrogance and ignorance are proving to be more dangerous pathogens than bacteria and viruses.

So I thought I'd close out the year with an uplifting look at a funding source not threatened by the current administration: the California Institute of Regenerative Medicine, aka CIRM.

Two Decades of Funding Research, Needed More Now Than Ever

CIRM was born 20 years ago, when 59 percent of California voters approved Proposition 71, and reaffirmed it in 2020. Since then, the taxpayer-supported organization has provided more than 1400 grants, totaling nearly $4 billion.

Grants support all stops on the journey from initial idea to delivering a new treatment. That means funding basic research at universities and supporting education, collaboration, scientific and medical meetings, as well as manufacturing facilities, clinics, hospitals, and community outreach programs.

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

Pluribus, Apple TV+'s sci fi series that just concluded its first season, is a clever take on the alien invasion theme, from Vince Gilligan of Better Call Saul fame. I enjoyed it, but wish the writers had consulted a scientist or two in creating the backdrop of genetics and cell and molecular biology.

The series honors Isaac Asimov's science fiction law of "change only one thing." An alien RNA virus infects people, robbing them of their individuality and their humanity as a "hive mind" forms across the planet, with the exception of thirteen individuals. But the writers demonize RNA (don't we have enough of that?) while conflating egg cells with stem cells.

Does accuracy really matter for plausibility in a sci-fi plot? I suspect I'm in the minority when I say yes, it does.

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

One of my greatest joys in revising my human genetics textbook is adding treatments for genetic diseases that have been FDA-approved since the last edition. The list has grown quite a lot since I finished the last revision as the pandemic finally faded away, and certainly since my gene therapy book was published in 2013. And so I was thrilled a few days ago when the father of a boy who had Menkes disease reposted my DNA Science blog from 2021, which described the rare disease, the clinical trial, and the family's participation.

The "new" treatment – many kids with Menkes have been part of the clinical trial for years – is a simple injection administered daily under the skin that delivers copper, which the body cannot process from food. It's not gene therapy, nor gene editing, nor magic – it is a sensible, decades-old strategy of finding a way around a biochemical glitch. Specifically, the drug Zycubo, aka copper histidinate, is a copper replacement therapy. Cyprium Therapeutics developed the long-awaited treatment.

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

With the pandemic past and vaccine-preventable infectious diseases creeping back, we don't think often about syphilis.

A new report in Science, from Davide Bozzi of the University of Lausanne, Switzerland and colleagues, uses DNA evidence to rewrite what we thought we knew about how and when European explorers brought the sexually transmitted infection here. It turns out, they likely didn't.

The genome sequence from a recently-discovered sample of a close relative of the modern bacterium that causes syphilis, in Sabana de Bogotá, Colombia, backdates the origin of the STI in North America to much earlier than previously thought. So European explorers might have picked the STI up here and brought it home, where it spread in the late 15th century.

The bacterium Treponema pallidum causes syphilis, which belongs to a group of infectious diseases caused by spiral-shaped bacteria (spirochetes) that includes yaws, bejel, and pinta. People have suffered with these diseases for thousands of years, but evidence from human remains is sparse, because the bacteria crumble bones. Obtaining long enough DNA molecules to overlap them and deduce the genome sequence from ancient microbial pathogens has been difficult.

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

As Thanksgiving approaches, thoughts turn to turkeys. This year, the holiday comes soon after announcement of the first steps in recreating dodo birds – could we breed "de-extincted" dodos for Thanksgiving?

Do the math.

The extinct birds grow up to 50 pounds, and people consume about 1.5 pounds of turkey for Thanksgiving, less if side dishes are plentiful. So a single dodo could feed perhaps 35 or so people, accounting for the inedible parts. Both birds grow to about three feet tall, but a modern turkey, especially a wild one, is trim compared to a dodo, which is basically an overgrown pigeon. A Dutch sailor in 1662 supposedly described the soon-to-be extinct bird as a "kind of very big goose."

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

Genetics is a field rich in numbers and patterns, reaching back to Gregor Mendel's crosses of pea plants with distinguishing characteristics that revealed the two basic laws of inheritance.

At a microscopic level, genetics is informational, a series of languages: a DNA sequence is transcribed into an RNA sequence, which is then translated into a sequence of amino acids comprising a protein molecule. The suite of proteins, with abundances ebbing and flowing as patterns of gene expression change in response to the environment, provides our traits, our abilities, and the myriad metabolic reactions that keep us going.

Because genetics is so highly informational, it is a natural target for artificial intelligence. AI can speed, enhance, and extend what we know about the meanings in our genes, transcending what we deduce from far simpler data. It digests (trains on) massive amounts of data, stores and analyzes them, then makes connections and provides insights beyond what a human mind could do.

A Very Brief History of AI

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