Japanese Scientists Remove Extra Chromosome Behind Down Syndrome

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Source : https://www.medindia.net/news/healthwatch/gene-editing-milestone-japanese-scientists-remove-extra-chromosome-behind-down-syndrome-220586-1.htm

Japanese Scientists Remove Extra Chromosome Behind Down Syndrome

Written by Dr. Nikitha Narayanan

Medically Reviewed by Colleen Fleiss M.Sc on Jul 29 2025 3:02 PM

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Japanese researchers have used CRISPR to remove the extra chromosome that causes Down syndrome, offering potential for future therapies — and raising key ethical questions.

Highlights:

• Japanese scientists used CRISPR to remove the extra chromosome that causes Down syndrome in lab-grown cells
• Corrected cells grew faster, had fewer stress markers, and showed improved biological function
• The technique worked on skin cells from people with Down syndrome, not just lab cells

Japanese scientists may have rewritten the future of Down syndrome research by using gene editing to remove the extra chromosome that causes the condition. In a groundbreaking lab study, researchers used the gene-editing tool CRISPR-Cas9 to target and delete the extra copy of chromosome 21 — the genetic cause of Down syndrome (1). The study, published in PNAS Nexus, is the first to demonstrate complete chromosome removal in human cells. It offers a glimpse into future therapies that may help manage, or possibly reverse, the biological effects of Down syndrome.

Down Syndrome - Trisomy 21, Causes, Symptoms, Diagnosis, Treatment, Prognosis
Down Syndrome is a congenital disorder among children commonly born to older mothers. The condition is also known as ‘Up syndrome’ because of the cheerful persona of the Down children.

Did You Know?
A genetic milestone: Scientists successfully remove the extra chromosome in Down syndrome cells using CRISPR-opening new doors for future research. #downsyndrome #crispr #geneediting #trisomy21 #medicalbreakthrough #genetics #chromosomeresearch #medindia

CRISPR in Action: Targeting the Root of Trisomy 21

Down syndrome, also called trisomy 21, occurs when a person has three copies of chromosome 21 instead of two. This extra DNA causes developmental delays, heart defects, and raises the risk for early Alzheimer's.

The research team, led by Dr. Ryotaro Hashizume at Mie University, used CRISPR, a genetic "scissor," to identify and cut the extra chromosome. Unlike traditional gene editing, which changes a small section of DNA, this method aimed to remove an entire chromosome.

In lab-grown stem cells, the scientists observed that removing the extra chromosome normalized gene activity, especially in genes related to brain development and metabolism. The edited cells also grew faster, produced fewer harmful stress chemicals, and had improved energy function.

Down syndrome also known as Trisomy 21 is a genetic disorder caused by the presence of a third copy of chromosome 21. Down syndrome leads to impairments in cognitive ability and physical growth of the ...

Real Cells, Real Impact: Beyond the Lab Dish

Importantly, the technique also worked in skin cells taken from people with Down syndrome. This success outside of stem cells suggests potential for broader applications, possibly in future regenerative therapies to improve organ function.

However, safety concerns remain. Some CRISPR edits unintentionally affected healthy DNA, raising the risk of off-target effects. Researchers are now refining the method to target only the extra chromosome, ensuring precision.

Top 10 Facts on Down Syndrome
Down syndrome or trisomy 21 is a genetic disorder, in which the affected children usually have an extra chromosome 21. Here are some interesting facts on Down syndrome.

A Medical Leap — But Also an Ethical Crossroad

While science moves forward, the idea of removing the cause of Down syndrome sparks deep ethical debates. In countries like Iceland, the condition is already rare due to prenatal screening. Some fear that eliminating Down syndrome through gene editing may send harmful messages about the worth and value of individuals with the condition.

The Japanese team emphasized that their goal is not to eliminate Down syndrome from society, but to understand how gene editing might reduce health complications linked to the condition.

CRISPR Gene Editing Technology
CRISPR technology allows for precise DNA modifications, holding promise for treating genetic disorders and revolutionizing biomedical research.

What’s Next? The Road Ahead

Experts agree: this gene editing isn’t ready for clinical use. More studies are needed to ensure safety, especially long-term monitoring of edited cells. Scientists also want to explore whether corrected cells could be used in future cell therapies for the heart, brain, or immune system.

Most importantly, any future treatment would need careful public discussion, including the voices of people with Down syndrome and their families.

Final Takeaway: Science, Hope, and Humanity Intertwined

This breakthrough shows how far science can go, from editing single genes to removing whole chromosomes. It brings hope for better health outcomes for people with Down syndrome. But it also reminds us to ask not just what we can do, but what we should do. As gene editing advances, thoughtful dialogue between science and society will shape what comes next.

Reference:

1. Trisomic rescue via allele-specific multiple chromosome cleavage using CRISPR-Cas9 in trisomy 21 cells - (https://academic.oup.com/pnasnexus/article/4/2/pgaf022/8016019?login=f