Imagine a world where the very building blocks of our DNA could be gently edited, removing what brings suffering, without erasing what makes us uniquely human.
That’s exactly the kind of future scientists are now daring to explore, thanks to a new breakthrough in gene editing that has the medical community buzzing with hope and raising some tough questions.
Editing out the extra chromosome
Recently, researchers at Mie University in Japan accomplished something that, until now, was only the stuff of science fiction: they used a tool called CRISPR-Cas9 to remove the extra copy of chromosome 21 from cells affected by Down syndrome.
Their findings, published in the journal PNAS Nexus, could mark the start of a new era in how we think about treating (and maybe even preventing) this common genetic condition.
“We designed our CRISPR system to target the extra chromosome without affecting the normal pair,” explained Dr Ryotaro Hashizume, the project’s lead scientist. “Our goal was to remove the surplus material and see whether the cell’s gene expression returned to typical levels.”
What is Down syndrome?
We’ve all heard of Down syndrome, but what actually causes it? In simple terms, it happens when a person is born with three copies of chromosome 21 instead of the usual two.
This extra genetic material disrupts the body’s usual blueprint, leading to a variety of challenges, from intellectual disabilities and heart defects to higher risks of Alzheimer’s disease and other health conditions.
Three main types of Down syndrome exist:
- Trisomy 21 (the most common): Every cell in the body has an extra chromosome 21.
- Mosaic Down syndrome: Only some cells have the extra copy, leading to milder symptoms.
- Translocation Down syndrome: The extra chromosome attaches to a different chromosome, which affects how symptoms appear.
Down syndrome is more common than many realise, affecting about 1 in 700 babies born in the world, according to the CDC.
While the chance increases with maternal age, most babies with Down syndrome are actually born to younger mothers, simply because they have more children overall.
How does CRISPR work its magic?
CRISPR-Cas9 is often called “genetic scissors”. It can cut DNA at precise spots, allowing scientists to remove, repair, or add genetic material. In the Mie University study, researchers programmed CRISPR to specifically target and cut the extra chromosome 21 in both stem cells and mature skin cells from people with Down syndrome.
Following the removal of the extra chromosome, the cells behaved more like typical cells:
- Their growth improved.
- They produced fewer harmful byproducts (linked to cell ageing).
- Genes related to brain development became more active.
This aligns with decades of research published in the National Institutes of Health showing that the extra chromosome 21 interferes with normal development.
What could this mean for people with Down syndrome?
If this technology ever leaves the lab, it could be revolutionary. Imagine therapies where a person’s own cells are edited and returned to their body, potentially improving heart health, boosting brain function, and reducing the risk of early-onset Alzheimer’s.
But (and it’s a big but), we’re not there yet. According to Hashizume, this technique is not yet ready for use in hospitals or in routine medical practice. But it sets a new benchmark for what CRISPR can do, not just editing single genes, but removing entire chromosomes.
Any conversation about “deleting” a genetic condition sparks strong feelings. What does it mean to change something so fundamental? Some families and advocates worry about losing the beauty and value in diversity, including the lives and personalities of people with Down syndrome.
And while prenatal screening has made Down syndrome rare in some countries, the global conversation is just beginning: Should we use science to eliminate a condition, or focus on making life better for people who live with it?
As we watch this story unfold, one thing is certain: the future of health, wellness, and genetics will be shaped not just by labs and scientists, but by all of us, families, advocates, and a world still learning to celebrate differences.
