Researchers are getting closer to being able to altering human genes by injecting CRISPR molecules into a fetus’s brain, according to news site focused on autism research Spectrum. The scientists concentrating on Angelman syndrome therapy have successfully performed the method in mice and say that it will likely be used to treat people with the syndrome in the near future.
And, more broadly, the technique could be used to treat DNA mutations causing autism. However, experts warn that the process of injecting enzymes into the brains of fetuses poses ethical concerns.
“People with Angelman syndrome have severe developmental delays, seizures, impaired speech and, often, autism,” Spectrum reports. “They have a missing or mutated copy of a gene called UBE3A on the copy of chromosome 15 they inherit from their mother. The paternal copy is generally silent, so they have virtually no activity of the protein in neurons, where it is needed to modulate signals between neurons.”
While researchers have attempted to unsilence the paternal copy of the gene in mice or to create an entirely new healthy copy of the gene, their approaches are largely impractical, involving frequent injections of harsh drugs.
But University of North Carolina professor Mark Zylka and his team presented new research on injecting the CRISPR-CAS9 enzyme into the brains of embryonic mice to edit their genes at a conference in February. This allowed them to rescue expression in the paternal UBE3A gene copy in the mice. The team of scientists were also able to do so in cultured human neurons.
“The earlier you put the genes back and try to fix the problem, the better the therapeutic benefit will be,” says Zylka. “There’s a lot of interest in trying to break down this barrier to being able to treat prenatally.” Zylka predicted that the treatment may see human trial in the next three or four years.
Some experts warn that before human trial, however, the study must be repeated in mice for validation. Moreover, scientists should work together to resolve any ethical concerns.
“Doing any gene manipulation in the fetal brain is kind of a dangerous thing to do, so that does concern me,” says Fred Hutchinson Cancer Research Center associate member Antonio Bedalov.
University of California, Davis chemistry professor David Segal said that scientists should proceed cautiously because this is an area of evolving research.
“The idea that you could treat a fetus with [an enzyme] is just a very uncharted area, and there could contain a lot of risks,” he said. “We need to move with caution.”