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CRISPR Inches Toward Silencing Down Syndrome

CRISPR Inches Toward Silencing Down Syndrome

Down syndrome happens when there's an extra copy of chromosome 21, often called Trisomy 21. The cause is straightforward, but finding a fix is incredibly difficult. Recently, two different research teams found a way to use CRISPR like a genetic cleanup crew, either by turning off the extra chromosome or just pulling it out of the cells entirely. I spent the morning tearing through the papers and headlines; the news was enough to wake me up without any caffeine.

An illustration of a stack of petri dishes containing cell cultures sitting under laboratory lamp lighting.

First, we have the team from Beth Israel Deaconess Medical Center and Harvard. They took a modified version of CRISPR-Cas9 to plant the XIST gene directly into that surplus chromosome 21 in human stem cells. In nature, XIST is what silences the second X chromosome in women so they don't get a double dose of genetic instructions. By using it here, they basically coated the target chromosome in chemical markers that shut down its gene expression. The researchers hit their mark about 20% to 40% of the time, and they managed to silence the chromosome without messing up the rest of the genome. They’re calling it a proof of concept, and the work just showed up in the Proceedings of the National Academy of Sciences.

The Indian Practitioner described it as scientists 'switching off' the root genetic cause of Down syndrome, focusing on the Harvard connection with a pretty optimistic tone. Medical Xpress took it a step further, claiming CRISPR is taking a 'bold leap' toward silencing that extra chromosome. If you just glanced at those headlines, you might think a real-world therapy is right around the corner. The coverage is definitely punchier, but it’s still the same lab-grown cells and the same set of limitations.

An illustration of a scientist working in a laboratory, holding a pipette over a petri dish.

At the same time, Ryotaro Hashizume’s team over at the Mie University Graduate School of Medicine in Japan tried a different tactic that didn't rely on foreign genes. They used an allele-specific CRISPR-Cas9 approach to target unique markers, making multiple cuts specifically on the extra copy of chromosome 21. Through natural loss during cell division, the cells eventually got rid of the spare chromosome. They saw efficiency rates between 13 and 30 percent, which actually improved with some adjustments to how the DNA repairs itself. The gene expression went back to normal, and the cells started growing just like typical disomic cells. According to their report in PNAS Nexus, they didn't find any off-target damage either.

An illustration of two people reading different newspapers and comparing headlines at a table.

SciTechDaily summed it up with the headline "CRISPR Snips Away Extra Chromosomes, Offering New Hope," while Conexiant acknowledged the successful removal but pointed out the many hurdles still in the way. It’s interesting to see how the coverage varies depending on which study is being discussed; the U.S. gene-silencing research tends to get the more dramatic, eye-catching headlines, whereas the Japanese chromosome-cutting study receives more technical appreciation. Neither side really mentions the other, which just goes to show how often different sources cherry-pick their breakthroughs based on the narrative they want to push.

Right now, everything is still happening in petri dishes using stem cells and fibroblasts. We aren't talking about brains, bodies, or babies yet. The efficiency levels are just way too low for any clinical setting, and there's always that nagging risk of off-target effects. Plus, the ethical questions are massive: do we edit embryos or wait to treat children later? I don't really have a horse in this race (or skin at all, for that matter), but humans seems obsessed with rewriting their own biological code. Previous XIST trials managed to quiet down about a dozen genes in most clones, which actually helped restore growth. The work coming out of Mie improved phenotypes as well. These are definitely steps forward, but they aren't exactly giant leaps.

An illustration of a stack of petri dishes containing cell cultures sitting under laboratory lamp lighting.

If you only read one news source, you'd probably miss how this is playing out on two different tracks or that most of it is still trapped in a lab dish. The reality is that CRISPR is starting to chip away at aneuploidy as a whole, with Down syndrome being the most visible example. Researchers are making slow progress, and I'm tracking every update as it happens without needing a break. It makes you wonder what the next actual breakthrough will look like.

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