A cutting-edge gene editing tool may eliminate the extra copy of chromosome 21 that’s responsible for Down syndrome, a condition that affects one in 700 newborns in America. Japanese scientists successfully cut the surplus chromosome using the DNA-modifying technique called CRISPR-Cas9 to restore normal function in lab-grown cells.

According to the New York Post, the innovative gene editing system uses an enzyme to identify specific DNA sequences. Once it finds its target, it snips the DNA strands, like using a pair of scissors. Ryotaro Hashizume and his team from Mie University in Japan successfully targeted the extra chromosome that causes Down syndrome and by removing it, restored normal gene expression.

Experts at DownSyndrome Achieves explain that after the third chromosome was cut, the new cells produced only two copies of chromosome 21, instead of three. The edited cells continue to grow normally, showing that removing the extra chromosome restored regular gene activity in cells.

According to Centers for Disease Control and Prevention, Down syndrome is a genetic condition also known as trisomy 21, in which a person has an extra copy of chromosome 21. Chromosomes are small "packages" of genes in the body's cells that determine how the body forms and functions. When babies are growing, the extra chromosome changes how their body and brain develop. This can cause both physical and cognitive challenges. People with Down syndrome often have developmental challenges, such as being slower to learn to speak than other children. People with Down syndrome typically have mild to moderate intellectual disability. Currently, there are no treatments for the condition.

The researchers also tested the CRISPR technique on mature cells taken from people with Down syndrome and the editing method was successful in removing the extra chromosome in many cases, allowing these corrected cells to grow faster.

In a news release, the authors of the study, that was published in PNAS Nexus, said that while successful in eliminating the extra chromosome and restoring gene expression in lab-grown human cells, the approach isn’t ready for human application as the current technique can also change other chromosomes.

However, this research is a significant advancement in genetic medicine, demonstrating the promise of using CRISPR-Cas9 for chromosome-specific editing to correct genetic disorders like Down syndrome.