Cure for Down syndrome promised with just a single injection

If you could give your loved one with Down syndrome a shot that would eliminate their extra 21st Chromosome, would you? This may be a very real question in the not too distant future. 

On November 27, 2017, it was reported that Chinese researchers had eliminated whole chromosomes in living organisms with gene-editing injections. Due to the hyper-technical language of the report, the potential ramifications have received little coverage.

Here is the lede from the news report:

the researchers developed an approach that used either multiple cleavages induced by one or two single-guide RNAs (sgRNA) that targets multiple chromosome-specific sites or a combination of 14 sgRNAs, each targeting a specific site, to selectively eliminate a sex chromosome in cultured cells, embryos, and tissues in vivo.

Like I said, the hyper-technical language buries the significance of this development. Translated, as best I understand this science:

researchers used gene-editing technology to eliminate sex chromosomes in cells, embryos, and in tissues of living animals.

But the researchers did not stop with the sex chromosomes. From the same GenomeWeb report:

The researchers next looked at whether they could eliminate an extra chromosome in aneuploid cells using CRISPR-Cas9 editing. They focused on an ES cell line with an extra human chromosome 14 (hChr14). … They were also able to apply this method to promote human chromosome 7 loss in human cancer cell line HT-29, which contains four hChr7s in most cells, and extra human chromosome 21 loss in aneuploid mouse ES cell lines derived from mice with Down syndrome.

(emphasis added). Again, translated:

The researchers then used CRISPR (a gene-editing technology) to eliminate an extra human chromosome 14 and chromosome 7 in human cell lines, and to eliminate the extra 21st chromosome in cells taken from mouse models with Down syndrome.

The report concludes:

The authors concluded that this is the first study that they know of to use CRISPR to eliminate X and autosome chromosomes, and as such, “it paves the way for a potential genetic approach to chromosome therapy in vivo.” It also offers “a new approach to develop animal models with chromosome deletions, and a potential therapeutic strategy for human aneuploidy diseases involving additional chromosomes,” they added.

Translated with the focus on “aneuploidy diseases”:

The authors concluded that this is the first study they know of to use CRISPR as potential chromosome therapy in living organisms with the potential for eliminating the extra 21st chromosome that is the cause for Down syndrome.

As a result of this research, then, if it progresses, it promises the potential of injecting individuals with Down syndrome with the CRISPR technology to eliminate the extra 21st chromosome.

This is revolutionary and would be world changing. But, that is not to mean it would be a change for the better.

Not too many years ago, a researcher published findings where her team was able to “turn off” the extra 21st chromosome in cells. The application of that technology, however, was limited to “treating” Down syndrome in an IVF cycle.

This new research now suggests the possibility of giving a person with Down syndrome a shot and the extra 21st chromosome would be eliminated. The individual would go from having 47 chromosomes, to having 46 like most everyone else. Should this possibility become a reality, undoubtedly, most will hail it has an amazing “cure” for Down syndrome–an unmitigated positive for eliminating a condition associated with intellectual disability and a range of health issues.

It will completely change the dynamic of prenatal testing. Instead of simply testing for a condition with no in utero or ex utero treatment, parents receiving a prenatal or postnatal diagnosis could then be asked if they wanted the CRISPR shot to eliminate the extra 21st chromosome.

And, not just new parents. Parents of older children would have it as an option.

Should this future come into existence, headlines will likely report that Down syndrome is being eliminated, at least in societies where the CRISPR shot is available on a widespread basis. New and expectant parents, it can be expected, will almost universally choose to have the shot, seeing it as a “cure,” a “treatment,” a blessing, even a miracle.

For parents of older children, it will be less of a universal uptake. Having gotten to know their child with Down syndrome, accepted and loved their child, and advocated for their child for years to be accepted for who they are, these parents will face a dilemma: “cure” their child and open up options and possibilities that may have been limited or foreclosed, or opt-out of the treatment and face criticism for choosing to disable their child.

For individuals with Down syndrome themselves who are competent to make their own medical decisions, they, too, will be given the option: remain how they’ve always known themselves, or, take a shot and potentially eliminate the challenges that peers and crass strangers have teased them for and gain capabilities to do things they’ve always wanted to do.

But, will the new and expectant parents, the parents of older children, and the individuals with Down syndrome facing the choice be fully counseled about the effects of the CRISPR shot. Putting aside the risk of mutations (which in the study were rare, but did occur), how can anyone adequately counsel about such a fundamental alteration to a person?

Perhaps the research will falter. Maybe it will only apply in limited situations. But, the news report does give us the opportunity to ask ourselves important questions:

If there was a cure for Down syndrome, would you choose it for your child and why?

Should Down syndrome be “cured”?

Is there something unique about having individuals with Down syndrome in society that they should be “conserved” rather than “eliminated”?

I welcome your answers to these questions in the comments.