This baby boy was treated with the first personalized gene-editing drug
Author: Antonio Regalado
Regalado, Antonio. "This Baby Boy Was Treated with the First Personalized Gene-Editing Drug." *MIT Technology Review*, 15 May 2025, https://www.technologyreview.com/2025/05/15/1116524/this-baby-boy-was-treated-with-the-first-personalized-gene-editing-drug/,
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The one-off treatment highlights the promise of a new type of gene editing and the challenges of using it to treat extremely rare genetic diseases.
KJ Muldoon, a baby treated with a personalized gene-editing drug, relaxes with his parents and siblings.Children's Hospital of Philadelphia
Doctors say they constructed a bespoke gene-editing treatment in less than seven months and used it to treat a baby with a deadly metabolic condition.
Words to Watch For
Based on your experience as someone learning English and living in the country for about four months, here are ten words or phrases from the sentence that might be difficult. I’ll give you simple, context-specific definitions to help you as you read:
1. Constructed – Built or made something.
2. Bespoke – Made especially for one person; custom-made.
3. Gene-editing – Changing or fixing the DNA in someone’s body to treat or cure diseases.
4. Treatment – The medicine or medical care given to someone to help them get better.
5. Metabolic – Related to how the body uses food and energy.
6. Condition – An illness, disease, or health problem.
7. Doctors – People who have studied medicine and help sick people get better.
8. Say – In this context, it means “report” or “explain.”
9. Used – Did something with; applied.
10. Deadly – Very dangerous, can cause death.
Say each word out loud to yourself or with someone else. You can refer back to this word list as you read the paragraph to help you understand!
Absolutely! Let’s work together to understand this sentence better, step by step. I’ll use a Think Aloud routine to show how we can use reading strategies to figure out the most difficult vocabulary. I’ll break the sentence into small, understandable chunks, and after each chunk, I’ll ask if you want to see more.
Here’s our first chunk:
Chunk 1:
Doctors say they constructed a bespoke gene-editing treatment…
Let’s pause and use Think Aloud to understand “constructed” and “bespoke.”
- Constructed: I notice the word “constructed” comes from the root word “construct,” which means to build or put together. The suffix “-ed” tells me it happened in the past.
- Bespoke: This word is less common. I remember that “bespoke” is sometimes used with clothing, meaning custom-made or specially designed for someone. Here, it describes the “gene-editing treatment,” so it must mean the treatment was specially made, not just off-the-shelf.
So, this part means: doctors built a special, custom-made treatment that changes genes.
Would you like to see more?
¡Por supuesto! Vamos a leer juntos y usar algunas estrategias de Reading Apprenticeship para entender el texto palabra por palabra. Vamos a dividir la oración en partes más pequeñas (chunks) y enfocarnos en las palabras difíciles. Te mostraré cómo pienso en voz alta (Think Aloud) para ayudarte a entender el significado.
Aquí está la primera parte:
Doctors say they constructed a bespoke gene-editing treatment
Voy a pensar en voz alta sobre esta parte:
- “Doctors say” significa “Los doctores dicen”. Esto nos dice que la información viene de personas con experiencia médica.
- “they constructed” significa “ellos construyeron” o “ellos crearon”. El verbo “constructed” viene de la palabra “construct”, que significa hacer o crear algo.
- “a bespoke gene-editing treatment” es una frase difícil. “Bespoke” significa “hecho a la medida” o “personalizado”. “Gene-editing” quiere decir “edición de genes”, que es cuando los científicos cambian partes del ADN para ayudar con problemas de salud. “Treatment” significa “tratamiento”.
Entonces, en otras palabras, los doctores dicen que crearon un tratamiento personalizado para editar genes.
¿Quieres ver la siguiente parte?
¡Hola! Entiendo que eres un estudiante de EL que lleva poco tiempo en este país. Voy a ayudarte a identificar palabras que podrían ser difíciles en el párrafo que me diste, para que puedas comprenderlo mejor.
Diez palabras difíciles y sus definiciones
1. Constructed – Hicieron o crearon algo, en este caso un tratamiento.
2. Bespoke – Hecho a medida o personalizado, algo creado especialmente para una persona.
3. Gene-editing – Editar genes; una técnica científica para cambiar partes del ADN de alguien.
4. Treatment – Tratamiento médico; lo que usan los doctores para ayudar a una persona a curarse.
5. Less than – Menos de; indica un tiempo más corto que el mencionado.
6. Seven months – Siete meses; una cantidad de tiempo, casi como medio año.
7. Used – Usaron o emplearon algo.
8. Deadly – Mortal, algo que puede causar la muerte.
9. Metabolic – Relacionado con el metabolismo, el proceso que usa el cuerpo para convertir comida en energía.
10. Condition – Enfermedad o situación médica.
Recuerda: puedes decir cada palabra en voz alta tú solo o con otros lectores. Puedes mirar esta lista cuando leas el párrafo para ayudarte a entender mejor. ¡Sigue adelante, lo estás haciendo muy bien!
The rapid-fire attempt to rewrite the child’s DNA marks the first time gene editing has been tailored to treat a single individual, according to a report published in the New England Journal of Medicine.
The baby who was treated, Kyle “KJ” Muldoon Jr., suffers from a rare metabolic condition caused by a particularly unusual gene misspelling.
Researchers say their attempt to correct the error demonstrates the high level of precision new types of gene editors offer.
“I don’t think I’m exaggerating when I say that this is the future of medicine,” says Kiran Musunuru, an expert in gene editing at the University of Pennsylvania whose team designed the drug. “My hope is that someday no rare-disease patients will die prematurely from misspellings in their genes, because we’ll be able to correct them.”
The project also highlights what some experts are calling a growing crisis in gene-editing technology. That’s because even though the technology could cure thousands of genetic conditions, most are so rare that companies could never recoup the costs of developing a treatment for them.
In KJ’s case, the treatment was programmed to correct a single letter of DNA in his cells.
“In reality, this drug will probably never be used again,” says Rebecca Ahrens-Nicklas, a physician at the Children’s Hospital of Philadelphia, who treats metabolic diseases in children and who led the overall effort to treat the child.
That effort involved more than 45 scientists and doctors as well as pro bono assistance from several biotechnology companies. Musunuru says he cannot estimate how much it cost in time and effort.
Eventually, he says, the cost of custom gene-editing treatments might be similar to that of liver transplants, which is around $800,000, not including lifelong medical care and drugs.
The researchers used a new version of CRISPR technology, called base editing, that can replace a single letter of DNA at a specific location.
Previous versions of CRISPR have generally been used to delete genes, not rewrite them to restore their function.
The researchers say they were looking for a patient to treat when they learned about KJ. After he was born in August, a doctor noted that the infant was lethargic. Tests found he had a metabolic disorder that leads to the buildup of ammonia, a condition that’s frequently fatal without a liver transplant.
The researchers approached KJ’s parents, Nicole and Kyle Muldoon, with the idea of using gene editing to try to correct their baby’s DNA. After they agreed, a race ensued to design the editing drug, test it in animals, and get permission from the US Food and Drug Administration to treat KJ in a one-off experiment.
The team says the boy, who hasn’t turned one yet, received three doses of the gene-editing treatment, of gradually increasing strength. They can’t yet determine exactly how well the gene editor worked because they don’t want to take a liver biopsy, which would be needed to check if KJ’s genes have really been corrected.
But Ahrens-Nicklas says that because the child is “growing and thriving,” she thinks the editing has been at least partly successful and that he may now have “a milder form of this horrific disease.”
“He’s received three doses of the therapy without any complications, and is showing some early signs of benefit,” she says. “It’s really important to say that it’s still very early, so we will need to continue to watch KJ closely to fully understand the full effects of this therapy.”
The case suggests a future in which parents will take sick children to a clinic where their DNA will be sequenced, and then they will rapidly receive individualized treatments. Currently, this would only work for liver diseases, for which it’s easier to deliver gene-editing instructions, but eventually it might also become a possible approach for treating brain diseases and conditions like muscular dystrophy.
The experiment is drawing attention to a gap between what gene editing can do and what treatments are likely to become available to people who need them.
So far, biotechnology companies testing gene editing are working only on fairly common gene conditions, like sickle cell disease, leaving hundreds of ultra-rare conditions aside. One-off treatments, like the one helping KJ, are too expensive to create and get approved without some way to recoup the costs.
The apparent success in treating KJ, however, is making it even more urgent to figure out a way forward. Researchers acknowledge that they don’t yet know how to scale up personalized treatment, although Musunuru says initial steps to standardize the process are underway at his university and in Europe.
by Antonio Regalado
General Document Comments 0
Great! Let’s use the Reading Apprenticeship approach to chunk this article so it’s easier for us to understand. We’ll break it into small pieces, and I’ll do a Think Aloud to show my reading strategies. Here’s the first chunk (just the headline and bold intro):
Chunk #1: Headline & Bold Intro
- The one-off treatment highlights the promise of a new type of gene editing and the challenges of using it to treat extremely rare genetic diseases.
Let me Think Aloud as I read this chunk:
- First, I notice the phrase “one-off treatment.” I wonder what that means. I think it probably means a treatment that is only done once, or is unique to one person.
- The sentence says this treatment shows both “promise” and “challenges.” So, it’s something new and exciting, but also difficult.
- I see the words “new type of gene editing.” That makes me curious—what is different about this gene editing compared to ones I’ve heard about?
- Finally, the sentence mentions “extremely rare genetic diseases.” I know that rare means not many people have them, so maybe this treatment is for special cases, not for everyone.
When I put all of this together, I think the article is about a new, special gene editing treatment that was used just one time, and it both shows hope for the future and points out some hard problems, especially for very rare diseases.
If I had to say this chunk in my own words, I’d say: “There’s a new, one-time gene editing treatment that shows exciting possibilities and tough challenges for treating rare diseases.”
Would you like to see the next chunk? If so, just say “more,” and we’ll keep going together. As we read, I invite you (and anyone in our reading group) to try your own Think Aloud with the next part! Let’s see what we can discover as we chunk the article.
https://www.technologyreview.com/2025/05/15/1116524/this-baby-boy-was-treated-with-the-first-personalized-gene-editing-drug/(https://www.technologyreview.com/2025/05/15/1116524/this-baby-boy-was-treated-with-the-first-personalized-gene-editing-drug/)
Awesome start, Paul! Let’s keep going with the next chunk. Here’s Chunk #2, which is the image caption and credit:
Chunk #2: Image Caption & Credit
- KJ Muldoon, a baby treated with a personalized gene-editing drug, relaxes with his parents and siblings.
- Children’s Hospital of Philadelphia (credit)
Now, I’ll Think Aloud as I read this chunk:
- First, I see the name “KJ Muldoon,” and I realize this is the baby the article is about.
- The phrase “treated with a personalized gene-editing drug” tells me that the treatment was made just for KJ, not for anyone else.
- The image shows KJ with his family, which helps me picture who is involved and reminds me that real people, not just science, are at the center of this story.
- The credit “Children’s Hospital of Philadelphia” tells me where the photo came from, and maybe where the treatment happened.
When I put all of this together, I understand that KJ is a real baby, and he was given a special gene-editing treatment made just for him. The hospital and his family are important parts of his story.
This chunk is helping me connect a name and a face to the treatment. I can see that KJ is the center of this breakthrough, and it makes the science feel more personal and real.
Would you like to see the next chunk of the article? If you say “more,” I’ll keep chunking and Thinking Aloud. And remember, anyone can jump in and try their own Think Aloud with the next part!
https://www.technologyreview.com/2025/05/15/1116524/this-baby-boy-was-treated-with-the-first-personalized-gene-editing-drug/(https://www.technologyreview.com/2025/05/15/1116524/this-baby-boy-was-treated-with-the-first-personalized-gene-editing-drug/)
¡Perfecto! Vamos a trabajar con el artículo usando la estrategia de Reading Apprenticeship. Vamos a leer y descomponer el texto en partes pequeñas para que sea más fácil de entender. Empezaremos con el primer fragmento.
Primer Chunk: Título y la Primera Frase
- “The one-off treatment highlights the promise of a new type of gene editing and the challenges of using it to treat extremely rare genetic diseases.”
- Voy a leer esta frase y pensar en voz alta. Primero, veo la palabra “one-off treatment”. Eso me dice que solo se hizo una vez, que no es algo común o repetido.
- Después, dice que esto muestra el “promise” o la promesa de un nuevo tipo de edición genética. Me hace pensar que este método nuevo podría ser muy bueno, pero todavía está en prueba.
- También menciona los “challenges” o desafíos de usar esto para tratar enfermedades genéticas muy raras. Entiendo que aunque la tecnología parece prometedora, hay problemas para usarla en enfermedades que casi nadie tiene.
Segundo Chunk: Pie de Foto
- “KJ Muldoon, a baby treated with a personalized gene-editing drug, relaxes with his parents and siblings.”
- Aquí, el texto nos presenta a KJ Muldoon, el bebé que recibió este tratamiento. La foto lo muestra con su familia, lo que ayuda a humanizar la historia y mostrarnos que es una persona real y no solo un caso médico.
- Esto refuerza la idea de que la edición genética personalizada puede impactar la vida de personas específicas y sus familias.
Ponemos todo junto
El artículo presenta un tratamiento único, hecho solo una vez, que nos muestra cómo la edición genética personalizada puede ser muy prometedora, pero también enfrenta grandes desafíos, especialmente para enfermedades muy raras. Además, nos presenta a KJ Muldoon, el bebé que recibió este tratamiento, lo que hace la historia más cercana y real.
¿Te gustaría que sigamos con el siguiente fragmento? ¡Dímelo si quieres ver más! Y si quieres, intenta hacer tu propio Think Aloud con alguna parte del texto. ¿Listo para continuar?
¡Genial, vamos avanzando paso a paso! Ahora, sigamos con el siguiente fragmento del texto y utilicemos la estrategia de Reading Apprenticeship para descomponerlo y entenderlo mejor.
Segundo Chunk: Primer párrafo (sobre el tratamiento y el reporte)
- “Doctors say they constructed a bespoke gene-editing treatment in less than seven months and used it to treat a baby with a deadly metabolic condition.”
- Voy a leer esta frase y pensar en voz alta. Aquí me fijo en las palabras “constructed a bespoke gene-editing treatment”. “Bespoke” significa que fue hecho a la medida, especialmente para ese bebé. El tratamiento fue creado en menos de siete meses, lo que suena rápido para algo tan complicado.
- El tratamiento fue usado en un bebé que tenía una condición metabólica mortal. Eso me ayuda a entender que la situación era muy grave y urgente.
- “The rapid-fire attempt to rewrite the child’s DNA marks the first time gene editing has been tailored to treat a single individual, according to a report published in the New England Journal of Medicine.”
- La frase “rapid-fire attempt” indica que todo fue hecho muy rápido. “Rewrite the child’s DNA” significa que intentaron corregir el ADN del niño, algo súper avanzado. Es la primera vez que la edición genética se usa de forma personalizada para una sola persona, según un reporte en una revista médica muy importante.
Ponemos todo junto
Los doctores crearon un tratamiento genético especialmente diseñado para un solo bebé con una enfermedad mortal, todo en menos de siete meses. Es la primera vez que la edición genética se usa de forma tan personalizada, según un reporte médico reconocido.
¿Quieres que sigamos con el siguiente fragmento del texto? ¡Avísame si quieres ver más! También puedes intentar hacer tu propio Think Aloud con esta parte. ¿Listo para continuar?
Thank you for sharing about your sister and the reason your family came to America. You mentioned, “My sister was sick when she was born. That’s one of the reasons we came to America.” This gives a very personal context to your question about the article, which describes a baby named KJ who was also born with a serious medical condition.
Looking at your question—**“Can you help me with this article?”**—let’s think together about how the article might connect to what your family experienced. The story of KJ and the groundbreaking gene editing treatment may resonate with you because your journey to America was shaped by your sister’s health needs, perhaps in search of better treatments or hospitals. In the article, doctors in the United States worked quickly to design a one-of-a-kind treatment for KJ, showing how access to advanced medicine can be a matter of life and death. Do you feel any similarities between why your family moved and what KJ’s family experienced when they sought out new options for their child?
The article points out that KJ’s “rare metabolic condition” meant that the doctors had to create a “bespoke gene-editing treatment in less than seven months.” This is not very different from families like yours who travel great distances hoping for medical breakthroughs that couldn’t be found at home. The emotional pressure, the hope for something miraculous, and perhaps the fear of not knowing if it will work—these might all be feelings your family and KJ’s family have shared. Reading the lines, “The researchers approached KJ’s parents…with the idea of using gene editing to try to correct their baby’s DNA. After they agreed, a race ensued…” can you imagine your own parents being in a similar position, having to make anxious but hopeful decisions for your sister’s future?
Another key idea from the article is about the challenge of treating extremely rare diseases. It says, “That’s because even though the technology could cure thousands of genetic conditions, most are so rare that companies could never recoup the costs of developing a treatment for them.” You might wonder whether your sister’s sickness was considered “rare” and if your family ever worried about whether there would be a treatment available for her. Maybe your family moved because, in America, there was a greater chance of finding doctors and scientists willing to try something new, as in KJ’s situation.
The article also ends with hope for the future—that “someday no rare-disease patients will die prematurely from misspellings in their genes, because we’ll be able to correct them.” Your family’s story and KJ’s are both examples of how medical science can change lives, but also of the obstacles that have to be overcome, especially for people with rare conditions. When you reread this article, do you notice other details that remind you of parts of your family’s story or feelings your family might have had?
So, in answering your question—**“Can you help me with this article?”**—I encourage you to reflect again on how this story of one family’s determination, new medical technology, and the hope for a cure is connected to your family’s own journey. What emotions or memories does it bring up? Are there parts of the article—about access, innovation, or family decisions—that feel especially meaningful for you? You might even want to reread the section describing how quickly the doctors worked, and ask yourself how it compares to your family’s search for help. Are there details that stand out even more now?
Let me know if you’d like to talk about specific parts of the article or how it makes you feel based on your own experiences.
on the uploaded document.
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