Kids with neurofibromatosis Type 1, or NF1, have a microdeletion, or a chunk of their chromosome missing.

Doctors have trouble treating this, because the mutation differs from patient to patient. But researchers at the University of Wisconsin-Madison say they have found a way around that.

"The biggest hurdle in this research area has been that there was no real way to study the disease because there aren't enough children with the same mutation," Dhanansayan Shanmuganayagam, director of UW-Madison's Biomedical & Genomic Research Group, told WNDU.com.

That’s where the pigs come in.

Using the CRISPR gene-editing tool, researchers genetically modify a pig embryo then impregnate an adult pig with it.

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"We're trying to create a pig that sort of represents a particular child," Shanmuganayagam said. "And therefore, we can really customize the treatment or the therapy."

Having a genetic twin of a patient can narrow down treatment options much faster. Without the pigs, a patient would have to recover from any adverse side effects of a failed treatment.

The first set of piglets engineered to match a Wisconsin 9-year-old girl were born in November 2016. There were eight, and four of the piglets carried the NF1 mutation.

"When we heard there would be a possibility of creating essentially a twin pig that has this microdeletion, it gave us hope," the girl's mother told WNDU.

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