The Hunt for Huntington's
How one daughter’s rebellion against fate drove a scientific revolution
One summer day in 1968, a young American woman received a phone call while vacationing in France. It was her father, asking her to come home for his 60th birthday. She was surprised; he was not usually sentimental about birthdays. Nevertheless, she hopped on a flight and flew to Los Angeles to meet up with her father and sister.
Milton Wexler picked up his daughters, Alice and Nancy, from the airport and drove them to his apartment. After an anxious ride, he sat them down and told them a story. The previous summer, a policeman had stopped their mother as she was walking across the street on her way to jury duty. “How can you be drunk so early in the morning? Shame on you!”, he shouted.
Leonore Wexler, a smart, law-abiding, 53-year-old retired biology teacher, wasn’t drunk. In fact, she rarely touched alcohol, let alone at nine in the morning. But she could see why the policeman thought so; she, too, had noticed her increasingly lumbering movement. Knowing what this might mean, she called Milton, who arranged an appointment with a neurologist that very same afternoon.
Leonore’s worst fear came true: she had Huntington’s disease.
The diagnosis was a nightmare she knew too well. Huntington’s had taken the lives of her father and her three brothers. Abraham Sabin, Leonore’s father, died in a state hospital on Long Island when she was 13. She overheard the doctor say he had Huntington’s chorea. After looking it up at the local library, she learned about the fatal neurological disease haunting her family. Chorea, from the Greek word for “dance,” cruelly expresses one of Huntington’s distinct symptoms: an uncontrollable writhing of the body, arms tracing arcs in the air, legs jerking in random directions, face twitching through a series of expressions — the opposite of dancing. She learned that there was no treatment and that, incorrectly, the disease afflicted only men.
Leonore went on to be the only one among her siblings to attend college. Keen to learn about her family’s affliction, she got her master’s degree in biology with a specialty in genetics at Columbia1. Her brothers took different paths: Jesse sold clothing, while Paul and Seymour started a swing band in New York City.
By 1950, the signs became impossible to ignore. Jesse, then 48, loved performing magic tricks, spinning coins, and pulling them out of his ears, nose, and pockets. Now, his fingers danced uncontrollably, and his coins fell to the floor. Paul, 44, and Seymour, 43, increasingly felt off-balance while walking and struggled to find words during conversations. In September 1950, a New York neurologist diagnosed all three brothers with Huntington’s on the same day.
Leonore was devastated by the news and descended into depression. Her brothers had funded her education, a path she took to understand the very disease now confirmed to haunt them. At 36, she was “fearful for what lay ahead for them and for herself.”
Milton hadn’t known about the disease in his wife’s family. When he learned that both men and women could be affected, he realized what this meant: Leonore might have passed it on to their daughters. It only deepened her anguish.
Facing his family’s genetic roulette, Milton, a former Navy lieutenant commander, sprang into action. He left the Menninger Foundation in Kansas in 1951 and moved his family to Los Angeles to start a more lucrative private practice, knowing he’d need to support his brothers-in-law and prepare for what might come. Despite the chaos, he clung to hope for his daughters. After Paul died in 1964, the second of Leonore’s brothers to pass, Milton assured Nancy and Alice that their mother would not get the disease. He truly believed that his daughters would be spared as well.
Back in the apartment in 1968, after finally revealing to Alice and Nancy the family’s affliction, Milton explained that they had a 50-50 chance of getting the disease. If they got it, then their kids would have a 50-50 chance of getting it too. There was no test to say if they had it or not. The two sisters finally learned the truth about their family that had been hushed away since they were children: their grandfather and all three uncles died from Huntington’s, and now their mother was destined to repeat this fate.
That afternoon, Nancy and Alice hung onto each other and sobbed uncontrollably, terrified of the “grim roulette” their lives had just turned into. Either to ease their father’s pain or their own, they told him that a 50-50 risk wasn’t so bad. They later revealed that they remember very little of the conversation — just that their mother was dying, and that they decided not to have kids.
The sisters juggled their university education with watching their mother slowly deteriorate. “She was sad, silent, listless, vague. It was as if some dark subterranean river was taking her away from me. In retrospect, I do not know if her decline was psychological, neurological, or both. Perhaps the ominous gene was already beginning to hold,” Nancy would recount.
If the “dark subterranean river” was, in fact, an effect of the “ominous gene,” then it was a mere foreshock before an imminent earthquake. About a year after her diagnosis, in 1970, one night at 3 AM, Leonore’s in-home nurse found her sleeping deeply with an empty bottle of pills next to her. She called Milton, who called an ambulance. A shot of stimulants to the heart and a pump of the stomach at the hospital revived her, but it was a close call.
For Nancy, her mother’s suicide attempt marked a pivotal moment. She immediately shifted gears from concerned daughter to cure hunter, barrelling towards finding out everything about Huntington’s. The curse became a challenge.
While pursuing her PhD in clinical psychology at the University of Michigan in Ann Arbor, Nancy learned about a group of people with Huntington’s that met up in Detroit. In the evenings and weekends, she would drive the sixty-mile journey into the city to talk with them about their problems. The group eventually formalized into the Michigan chapter of the Committee to Combat Huntington’s Disease (CCHD), the organization founded by Marjorie Guthrie after her ex-husband, the famous folk singer Woody Guthrie, died from the disease. These conversations often left Nancy “feeling so depressed and exhausted that she would almost fall asleep during the long drive home.” Still, Nancy would quickly become the vice-president, then president of the chapter.
As Nancy immersed herself in the world of Huntington’s — university research, doctoral dissertation, CCHD meetings — Milton and Alice grew increasingly worried. One of the small tragedies within families with hereditary diseases like this is that every conversation and interaction begins to revolve around it, so much so that other events and dreams get drowned out. But barring occasional outbursts — “ENOUGH HD!!!!!!!!”, she wrote in a letter in 1973 — Nancy felt inspired rather than cursed by the resilience she witnessed among the interviewees, determined to “turn [herself] inside out to cure this thing.”
As her fame grew, another personal challenge loomed at home: her mother’s deteriorating condition. Leonore was “terrified, helpless, depressed and often over-medicated.” As her disease progressed, she was moved into a succession of nursing homes. Nancy would harrowingly chronicle her mother’s decline there:
She said she felt like she was in quicksand, trying desperately to keep from going under.
If she sat relaxed, her fingers kept up a constant motion, as if she were playing a sad tune on a silent piano. Her face twisted, her toes jumped. […] When she walked, her left side sagged, and her legs sometimes buckled suddenly, as if she had been hit at the back of her knees.
Nancy and Alice would eventually take on the role of caregiver:
As she became increasingly ill, I dressed her, carried her, helped her brush her teeth and go to the bathroom, fed her and, mostly, held her and kissed her. Her eyes still haunt me with their sadness and fear. Even possessed by chaotic violent movements, she could be graceful. Until close to the end, she had a sense of humor, and we could sometimes tease her from her worries. She always knew us.
Over time, her mother got frailer, her speech less intelligible, her twitching more chaotic. After a decade of living in nursing homes, on May 14, 1978, Leonore Wexler died.
Following the cremation, Nancy and Alice held a private service, reading letters from their mother’s early days, re-creating the vibrant, cheerful, intelligent woman they wanted to remember. They found themselves “strangely at peace, closer to our mother than we had in a long time.”
No Slides, No Speeches: The Hollywood Psychotherapist’s Workshop
In 1968, shortly after his wife’s diagnosis, Milton Wexler founded the Hereditary Disease Foundation (HDF). Its mission was simple in theory: to find the cause and cure for Huntington’s disease. Unlike the CCHD, which was more focused on patient care and education, the HDF was created to fund transformative research to find treatments and ultimately a cure.
Milton Wexler was in a favorable position to start this. Described as the “psychotherapist to the stars”, his practice counted actors, directors, singers, and architects among its clients — ideal for fundraising. The techniques he developed to bring out the best in creatives, particularly his “group process” encouraging bold, wide-ranging discussions, had proved to be successful with his artistic clients. Would they also work with scientists?
Milton thought so, and began organizing workshops unique for science at the time. They were multidisciplinary — bringing together scientists, clinicians, patients, and public figures — and they were small — just “fourteen to fifteen around a table, at most seventeen.” He recruited the brightest young minds regardless of domain, those familiar with the newest technologies, and paired them with experienced geneticists. There were to be no slides and no presentations, just an “open and unconstrained atmosphere” where everyone was encouraged to share their crazy ideas. Every workshop began with a family affected by Huntington’s sharing their story, reminding scientists, many of whom had never seen a person with the disease, of the human stakes of their research. They also came with some unique perks: Milton occasionally tapped into his Hollywood connections and, some nights, scientists might find themselves at a party in the home of a movie star.
It was at one of these workshops, in Bethesda in 1979, where disparate pieces of the Huntington’s puzzle would finally fall into place, revealing to Nancy a promising new avenue in her quest to understand the disease. For years, finding the Huntington’s gene had seemed like searching for a single sentence in a library of three billion letters. But new molecular tools were about to make that search feasible.
“Leaping gazelle-like through the genome”
Scientists have been trying to understand DNA, the code of life, for centuries. By the mid-1970s, thousands of illnesses had been identified as genetic, but the actual genes that caused the illness — often just one — were still unknown. If these diseases were to be cured, scientists sensed they first needed to be understood.
But with what tool? Scientists could learn how Huntington’s destroys families across generations, could document every cruel symptom, yet had no way to find the gene responsible. The question haunting researchers was simple but seemed impossible: how do you locate a single defective gene among three billion base pairs of DNA? What’s the difference between those with Huntington’s and those without?
By the late 1970s, many approaches to understanding Huntington’s had stalled. Investigating dopamine imbalances like those found in Parkinson’s, neurotransmitter deficiencies, and skin cell membrane defects had each led to negative findings, practical barriers, or inconsistent results.
But a new technology was emerging. In the early-70s, recombinant DNA techniques were revolutionizing molecular biology. Scientists had discovered that restriction enzymes, originally a defence mechanism of bacteria against foreign DNA, could work as molecular scissors that could recognize and cut DNA at specific sequences with exceptional precision. This ability made it possible to then clone fragments of human DNA and to visualize them through a technique called Southern blotting, revealing specific sequences as dark bands on film2.
Experimenting with these tools led to a crucial discovery. In the mid-1970s, David Botstein and Ronald Davis, geneticists from MIT and Stanford, found that humans carry small variations in DNA — sometimes just a one-base-pair difference — that usually did not cause any change in appearance or function. These harmless variations, called polymorphisms, were scattered throughout the genome.
When cut with a specific restriction enzyme, these variations changed where in the DNA the cut occurred, producing fragments of different lengths3. On Southern blots, these then appeared as distinct patterns, with the shorter fragments represented by bands near the bottom, and longer fragments closer to the top, creating a sort of molecular fingerprint. Because restriction enzymes revealed these polymorphisms through fragment length differences, they were called restriction fragment length polymorphisms, or RFLPs.
The breakthrough came when researchers realized RFLPs could serve as genetic landmarks. The principle, called linkage, is elegant: genes located physically close together on a chromosome tend to be inherited together. Consider a thought experiment: imagine the hemochromatosis gene sits on chromosome seven, and the gene governing hair texture is its immediate neighbor. If the defective hemochromatosis gene arose in an ancestor with curly hair, both variants travel together through generations — chromosomes rarely splinter. Over multiple generations, a statistical pattern emerges: curly-haired children in this family tend to have hemochromatosis4. By following the pattern of molecular fingerprints through a family tree, researchers could follow the disease — even without knowing what the disease gene looked like.
By 1978, these advancements in molecular biology had not yet been considered in the quest for understanding Huntington’s disease. That same year, at a conference in Utah, Botstein, Davis, Raymond White, Mark Skolnick, and other researchers had proposed using RFLPs to map the human genome. They theorized that roughly 150 RFLPs, spread like landmarks across all the chromosomes, could locate any gene through its inheritance pattern. The approach’s potential was demonstrated that year when researchers found an RFLP next to the beta-globin gene responsible for sickle-cell anemia, the first disease diagnosable prenatally using these markers. The culprit gene had been narrowed from an entire city to a single neighborhood.
Could it work for Huntington’s? Unlike sickle-cell anemia, where the faulty protein was known, Huntington’s remained mysterious. But the approach was promising. The central question became: how much work would it take to find an RFLP marker linked to the Huntington’s gene?
This was the focus of that pivotal HDF workshop in Bethesda in October 1979. Botstein, White, and several pioneering geneticists and molecular biologists gathered. As Nancy recalled, the meeting quickly turned into “total pandemonium” with everyone “yelling and screaming… and scribbling furiously.” Botstein and White felt that before looking specifically for the Huntington gene marker, a “map” of the whole genome was required, which they estimated would take about ten years. David Housman, the principal investigator at MIT, countered that that was too long a wait to start, and that they should test each newly identified RFLP as it emerged. It was a gamble — “leaping gazelle-like through the genome,” as Botstein put it, was an “enormously complex, time-consuming process” — but it could mean saving years.
Nancy was willing to gamble. Her reasoning was that even if it’s more work, testing the markers as they came along would increase the probability of finding the disease sooner; so they should do it. There was a buzz around this new technology, and everyone felt that it would eventually work. The only real issue was finding the right families. The technique required large kindreds spanning generations, ideally living close together under similar conditions. American families were not large enough and too scattered. “The real key to human gene mapping,” Botstein had realized, “was not finding the gene, but finding the humans.”
Nancy knew exactly where she might find such large families. Seven years earlier, at the 1972 Centennial Symposium in Columbus, Ohio, she had witnessed a remarkable presentation by Ramón Avila-Girón, who played a short film showing families afflicted by Huntington’s in the stilt villages surrounding Lake Maracaibo in Venezuela. The movie had left an indelible impression on her, and the idea that these families might play an important role in her quest was planted in her mind. In July 1979, she had already made an exploratory field trip to Venezuela to look for children that have both copies of the faulty Huntington’s gene — the homozygote. Now, at the October workshop, she and her team realized that the Venezuelan communities might hold the key to the markers.
“There have been few times in my life when I felt convinced that something was really right,” Nancy wrote later, “times when my heart has raced and leapt into my throat, times when I couldn’t sit still and wanted to race as fast as I could, laugh wildly or explode. I had this feeling at the end of the workshop.” She then planned a serious expedition to South America.
Blood Samples and Family Trees
In March 1981, Nancy and a team of seven American researchers and five Venezuelan researchers began their first expedition, traveling to San Luis, Barranquitas, Lagunetas, and other stilt villages along Lake Maracaibo. The goal was to continue looking for the homozygote, and to begin creating a family tree for the communities, taking blood samples to follow the inheritance of Huntington’s and enable the genetic linkage analysis.
To court the cooperation of residents, Nancy enlisted Dr. Américo Negrette, who had documented Huntington’s in the area two decades earlier and was trusted by the communities, along with Ramón Avila-Girón, whose film she’d seen at the conference, and other Venezuelan partners. Convincing the residents, however, would take more than some friendly, earnest faces. At an informal party in the barrio, Nancy shared in her pidgin Spanish that she too had Huntington’s — el mal, as the locals called it — and their goal was to find the cause and cure. The families were stunned to hear that this disease existed outside their towns. Some didn’t believe her. But Fidela Gomez, the team’s nurse, held up Nancy’s arm and walked her around the room, pointing out the biopsy scar on her arm. The gesture made them understand; they no longer doubted their visitors.
Alice Wexler joined on two of these trips and beautifully captured what their research looked like: kids darting around the meeting room while adults shooed them outside; walls covered with family tree charts peppered with Polaroid photographs and names; researchers rehearsing their questions in Spanish between check-ups. Children crowded the sidewalks, mimicking neurological exams, performing the “follow-my-finger” ritual just as they saw the neurologists do. Draw days were particularly intense — the team had 48 hours to obtain, package, and ship the samples to laboratories in Maracaibo, Caracas, or Boston.
Every year for the next decade, more or less the same team made the trip to the stilt villages. In the sweltering heat and humidity, they ran neurological tests, conducted questionnaires, and collected blood samples and personal information. Nancy played the role of “physician, nurse, ethnologist, psychologist, diplomat, photographer, neurologist, geneticist, and general all rolled into one.” By the end, the team had collected nearly 4,000 blood samples from healthy and sick individuals, and the family tree they created encompassed over 18,000 individuals. After some local investigation, they even managed to trace the origin of the mutated gene to a woman who was believed to have lived in Laguneta in the 1800s, aptly named Maria Concepcion.
Patterns in the Dark
The blood samples were shipped to James Gusella at the Massachusetts General Hospital in Boston and to Michael Conneally at Indiana University. After the October 1979 workshop, Gusella began testing RFLP markers on a small Huntington’s disease family lineage from Iowa. By the spring of 1983, they had tested eleven markers without success.
Then came the twelfth probe, called G-8, named after technician Ginger Weeks. When tested on the Iowa family, the results showed promise — the LOD score, a statistical measure of genetic linkage, was 1.8, about 63-to-1 odds that they were linked. This was good, but not high enough. The researchers were looking for a LOD score of at least 3 — 1000-to-1 odds — to be “definitively significant.”
Gusella decided to test G-8 on DNA extracted from the Venezuelan kindred, realizing that the sheer size of that family could provide the definitive proof needed. In late July 1983, as Gusella and his technician sat down to read the autoradiograms, they saw that the inheritance patterns “matched perfectly.” Individuals with Huntington’s disease in Venezuela consistently carried a specific DNA fragment pattern — a “C haplotype” — while those without the disease carried a different pattern. Conneally’s statistical analysis confirmed it: the LOD score was above 6. Better than a million-to-one odds.
Their paper published in Nature revealed that the Huntington’s gene was somewhere on the short arm of chromosome four. Gusella estimated that their G-8 marker lay at least four million base pairs away from the gene – close enough to create a predictive test that was 95% accurate for families with sufficient genealogical information. It was the first time this RFLP technique had successfully located a gene for an inherited disorder whose chromosomal location was completely unknown. James Watson later stated that this result helped launch the Human Genome Project.
The invention of the predictive test created a new ethical and emotional quandary: does one want to know whether they will get a debilitating and fatal disease for which there is no treatment or cure? The answer, it turned out, wasn’t simple. In the Wexler family, taking the test they had worked so hard to make a reality seemed like a terrifying idea. Their entire lives, Nancy and Alice felt that they would not get it, since their father kept confidently saying so. The “denial” the sisters had cultivated — now revealed as an intentional tool fostered by Milton — allowed them to live somewhat normally with the ambiguity. A test now would shatter that deniability. “The thought of learning that I carry the gene — that my brain is already deteriorating — is just too horrendous. I’m not sure I could go on.” Alice wrote in her diary in May 1984. Nancy was worried too: “If the test showed I have the gene,” she wrote in 1991, “would I continue to feel the happiness, the passion, the occasional ecstasy I feel now? Is the chance of release from Huntington’s worth the risk of losing joy?”
Milton urged them not to take the test, pointing out that the 5% chance of error added yet another layer of ambiguity. The test became the subject of many family arguments.
When tests started rolling out across the United States, Canada, and Great Britain, relatively few people took them. Alice Wexler decided to ask some test-takers why. One fifty-year-old man revealed, “My feeling was that I did have it, so it would not be that awful to find out for sure.” He was among several people she interviewed who always believed they would get it — a confirmation would erase the ambiguity and help them plan better, while a good result would change their lives. For them, it was upside either way.
Chromosome Walking with the Gene Hunters
While the G-8 marker discovery was an accomplishment, it was not the gene itself. That remained about four million base pairs away, and the task now was to physically traverse this distance along the chromosome, like searching every address in a neighborhood. To find the gene as soon as possible, at a January 1984 HDF workshop, Nancy persuaded researchers to form an unprecedented collaboration of six laboratories across the United States and Britain. Formally, they were known as the Huntington’s Disease Collaborative Research Group (HD-CRG). Informally, they were “The Gene Hunters.”
By early 1986, the group had narrowed the search to a region at the top of chromosome four, from the G-8 marker to the tip. The goal was now to find a marker on the other side, called a flanking marker, creating a “fence” around the target gene.
That turned out to be a lot trickier than expected. Contradictory data from Venezuelan siblings pointed at two different possible locations: the tip of chromosome four, or the inner region. Researchers focused their hunt on the tip region, suspecting it would be there, but it turned out to be a bizarre and intractable area. The tips of chromosomes are more inclined to recombination events during reproduction, scrambling up the statistical patterns through inheritance they were checking. After years of searching, in 1990, they realized that the gene wasn’t there. They’d been looking in the wrong place.
It had been seven years since the breakthrough marker discovery with still no gene to show. The frustration was starting to build up, but the camaraderie of the collective structure kept them going. As they began searching in the inner region, a clue surfaced. Housman had recently found the gene for myotonic dystrophy, where “a short sequence of three nucleotides that is usually repeated just a few times undergoes abnormal expansion,” mangling the protein’s functioning and causing the disease. At a January 1992 HDF workshop, he wondered if Huntington’s was caused by this same abnormal trinucleotide repeat.
The clue proved crucial. On February 24, 1993, James Gusella and his team identified the Huntington’s gene, initially named IT15 — “interesting transcript 15” — and later renamed huntingtin, or HTT. The “longest and most frustrating search in the annals of molecular biology” was finally over. In recognition of the unprecedented scientific cooperation, their paper, published in Cell a month later, listed its author as the Huntington’s Disease Collaborative Research Group, with the 58 members of all six labs credited underneath.
Located 3.5 million base pairs from the tip of chromosome four, the gene was enormous: 170,000-180,000 base pairs long. The normal gene contained a CAG triplet — CAGCAGCAG… — that repeated about 17 times on average, ranging from 10 to 35 normally5. The mutation that causes Huntington’s increases the number of repeats to more than forty, sometimes exceeding a hundred. The more repeats, the earlier the symptoms occur and the higher the severity.
Huntingtin, the protein encoded by the gene, is a massive 3000-plus-amino-acid protein, expressed in nearly all cells, particularly neurons. It acts as a traffic-controller, helping move vesicles and organelles and organizing other proteins to ensure they hum along on their cellular pathways. When the CAG repeat is abnormally long, the protein misfolds and gets abnormally cleaved, forming clumps that derail its function. This dysfunction devastates neurons, eventually causing the cognitive drift and macabre dance that are Huntington’s telltale signs.
For those who had dedicated their lives to the search, finding the gene brought overwhelming triumph, relief, and elation. Nancy was just about to leave for South America when she received the news. “It was incredible,” she shared. “I just started screaming at the top of my lungs: ‘We found the gene!’ I called my dad. I said, ‘Dad, we did it,’ and he started crying. I called my sister. It was just euphoric.” Milton, then 84, was thrilled to see this discovery in his lifetime. James Gusella and his team felt “pure joy,” thrilled that the search was over. David Housman did what he always does after a significant discovery: he went out and had a beer.
Finding the gene simplified the presymptomatic test — no family structure requirements, just a simple blood test. But, since there was still no cure, the psychological uncertainty around the test didn’t change all that much.
Nancy and Alice both decided not to take the test. Recent reports indicate that Alice, now 83, has not developed any symptoms. Nancy’s fate, however, unfolded differently. Today, at 80, Nancy Wexler lives with the disease that has haunted her family for generations. Her speech slurs. Her limbs jerk in random directions. When she walks, her gait has the same unsteady rhythm her mother’s once did. The movements are involuntary, relentless, unmistakable.
But her mind remains sharp. In 2024, she participated in an extensive interview with the Lasker Foundation, discussing her life’s work and the science she has championed for decades, talking about gene mapping breakthroughs to therapeutic possibilities. Through the involuntary twitching and trembling, her voice carries the same passion it has since the day they began hunting for the gene.
While the disease may choreograph its cruel dance through her body, it never controlled her life’s meaning. That summer day in 1968, when Milton told his daughters they faced a 50-50 chance, none of them could have known what would follow. Milton would create a new model for scientific collaboration, bringing together minds that would never have otherwise met; the Venezuelan families would trust outsiders with their blood and their stories; James Gusella and the Gene Hunters would persist through seven frustrating years after the initial breakthrough, finally finding the gene; and Alice would stand beside her sister through it all, documenting the human cost as Nancy orchestrated the science.
Nancy’s curse became a challenge, and then a coordinate on chromosome four. The huntingtin gene still lurks in her DNA, just as it did in her mother’s, her uncles’, her grandfather’s. But because of the legacy they all built together, it no longer lurks in darkness. Huntington’s disease is a problem with a location, a mechanism, and now an experimental treatment. Families around the world now have a choice her mother never did.
Thank you to Mike Riggs and Maoreen Rose Malibiran for feedback and edits.
Her master’s thesis came from studying Drosophila in Thomas Hunt Morgan’s now-famous “fly room”.
To clone human DNA, it would be inserted into a bacterial plasmid – tiny, circular pieces of DNA – that would then be made by the millions as bacteria reproduced.
Let’s say two people have two separate polymorphisms: ACAATGCC for one, AGAATGCC for the other, and let’s say a restriction enzyme recognizes the sequence ACAAT and cuts between the C and the A. Then the first sequence will get cut into two fragments, AC and AATGCC, and the second one won’t get cut since the specific “recognition site” of ACAAT isn’t there.
This example is adapted from Siddhartha Mukherjee’s The Gene: An Intimate History
CAG is short-form for the nucleotide bases cytosine, adenine, and guanine. Every three nucleotide bases, known as a codon, encodes an amino acid, the building blocks of proteins. CAG encodes the amino acid glutamine.
Great timing, just days after the announcement of the successful treatment.
Thanks for this insightful post! I can imagine you started documenting and writing it before that announcement...
What a fascinating story well told!