Return of Alpha Gal
A RadioLab episode explores how Amy Pearl developed a sudden allergy to red meat after a tick bite, discovering the culprit is alpha-gal, a sugar found in non-primate mammals. The episode then updates listeners on how this discovery led to the creation of genetically modified GalSafe pigs that can provide organs for transplant and safe meat for alpha-gal allergy sufferers.
Summary
The episode begins with Amy Pearl's harrowing story of developing an unexpected allergy to red meat. Despite being a lifelong meat enthusiast who frequented steakhouses like Peter Luger's, Amy experienced severe allergic reactions including hives, difficulty breathing, and anaphylaxis after eating lamb and later beef. Her doctor initially dismissed the possibility of a meat allergy, but Amy persisted in investigating.
Science writer Peter Smith and allergist Thomas Platts-Mills eventually identified the culprit: alpha-gal, a sugar present in all non-primate mammals. Platts-Mills noticed the allergy cases clustered geographically in areas matching the distribution of Rocky Mountain spotted fever and the Lone Star tick. He theorized that tick bites were the trigger, a hypothesis he tested on himself by deliberately getting bitten by 200 seed ticks during a hike, after which he developed the allergy himself.
The mechanism behind alpha-gal syndrome involves the tick injecting saliva containing alpha-gal into the skin, which primes the immune system to attack alpha-gal as a foreign invader. Subsequently, when the person consumes meat containing alpha-gal, the immune system launches an excessive inflammatory response, causing severe allergic symptoms.
The episode's update reveals that this discovery inspired the company Revivicor to develop the GalSafe pig—a genetically modified pig with the gene producing alpha-gal removed. Initially created for medical transplantation purposes, the FDA approved it for food use after Revivicor heard Amy's RadioLab episode and recognized the potential to help alpha-gal sufferers. Ironically, they named the first pig slaughtered for meat 'Amy' after Amy Pearl.
The update also discusses the broader implications of using genetically modified pigs for organ transplantation, noting that the first pig kidney transplant into a living human patient occurred in March 2024. While this raises ethical questions about animal exploitation, the urgency of the 90,000-person kidney transplant waiting list provides compelling counterargument.
About this episode
Tuck your napkin under your chin. We’re about to serve up a tale of love, loss, and lamb chops - with a side of genetic modification.
Key Insights
- Amy Pearl developed a sudden allergic reaction to red meat years after regularly consuming it, which doctors initially dismissed as impossible since adults don't typically develop allergies to foods they've eaten for decades.
- Thomas Platts-Mills identified alpha-gal, a sugar found in all non-primate mammals, as the allergen responsible for sudden-onset meat allergies by examining patients who had severe reactions to a cancer drug containing this sugar.
- Geographic mapping revealed that alpha-gal syndrome cases clustered in areas matching the distribution of the Lone Star tick and Rocky Mountain spotted fever, leading to the hypothesis that tick bites were the trigger.
- The proposed mechanism involves tick saliva introducing alpha-gal into the skin through injection, where the immune system's surveillance system flags it as dangerous, causing subsequent meat consumption to trigger severe allergic responses.
- Platts-Mills deliberately exposed himself to 200 seed ticks during a hike to test his hypothesis, and subsequently developed the alpha-gal allergy himself after eating lamb chops, confirming the tick-allergy connection.
- After hearing Amy Pearl's RadioLab episode, Revivicor's scientists realized their genetically modified GalSafe pig—created for organ transplantation—could also serve as a food source for people with alpha-gal syndrome.
- The FDA approved the GalSafe pig for both medical transplantation purposes and food production, making it the first genetically modified animal approved for human consumption in the United States.
- Despite the solution now being available to her, Amy Pearl chose not to return to eating red meat, having found alternative foods satisfying and viewing her forced vegetarianism as ethically and environmentally beneficial.
Topics
Transcript
Radio Lab is brought to you by Progressive Insurance. Insurance isn't one size fits all. That's why drivers have enjoyed Progressive's Name Your Price tool for years now. With the Name Your Price tool, you tell them what you want to pay, and they'll show you options that fit your budget. So whether you're picking out your first policy or just looking for something that works better for you and your family, they'll make it easy to see your options. Visit Progressive.com, find a rate that works for you with the Name Your Price tool. Progressive Casualty Insurance Company and Affiliates, price and coverage match limited by state law. Hello, it's Lulu. It's summer here in the Northern Hemisphere, which…
Full transcript available for MurmurCast members
Sign Up to AccessMore from Radiolab
Neither Confirm Nor Deny
Radiolab explores the origins and consequences of the phrase "neither confirm nor deny," tracing it to a 1975 CIA response about a covert Cold War submarine recovery mission. The phrase has since become ubiquitous across government agencies and popular culture, creating legal and transparency challenges that can delay public accountability for years.
The Holy Shiver
Radiolab investigates goosebumps, exploring how this vestigial survival reflex evolved from a thermoregulation mechanism in mammals to trigger aesthetic chills in response to music, art, and emotionally meaningful experiences. Scientists Nico Regensi and Felix Schöller have developed methods to reliably induce chills in laboratory settings and are studying their potential therapeutic applications for depression.
Atomic Artifacts
Radiolab explores a secret Cold War-era government project to preserve artifacts that would survive nuclear apocalypse, then asks modern Americans what items should represent American identity in a post-catastrophic future. The episode examines what objects and values truly define America.
The Gondolier
This Radiolab episode tells the story of Alex Hay, a transgender man who became internationally known as the first female gondolier in Venice's 900-year history, only to later publicly transition and face severe discrimination. The episode explores how Alex's identity was hijacked by media narratives and feminist movements, leading to his eventual loss of livelihood and a six-year period of homelessness and depression before finding stability in Berlin.
This is Your Brain on Hormones
This Radiolab episode explores how hormones — particularly estrogen, progesterone, and testosterone — physically and functionally change the brain over time, both across the 28-day menstrual cycle in females and the 24-hour circadian cycle in males. Neuroendocrinologist Emily Jacobs and graduate student Laura Pritchett conducted a pioneering self-study called '28andMe,' scanning Laura's brain daily throughout her menstrual cycle to capture dynamic hormonal effects on brain structure and connectivity. The findings reveal that hormone fluctuations are a universal organizing principle of the brain, not a female-specific liability.