Could Gene Editing Pigs Be the Future of Treating Rare Diseases?

The Atlantic featured this incredible story about the possibilities of using genetically altered piglets as avatars for children with genetic diseases.

Furthermore, the article delves into the personal story of one the featured researcher’s children, who suffers from a rare incurable disease, neurofibromatosis type 1 (NF1).

What is Neurofibromatosis Type 1?

Neurofibromatosis type 1 (NF1) is a genetic condition characterized primarily by changes in skin color and the growth of benign tumors along the nerves of the skin, brain, and other parts of the body. NF1 belongs to a group of related conditions called the RASopathies.

Besides the development of benign tumors known as neurofibromas, other symptoms include:

  • Cancerous tumors that grow along nerves (malignant peripheral nerve sheath tumors)
  • Increased risk of developing other cancers, including brain tumors and leukemia
  • Benign growths called Lisch nodule in the colored part of the eye iris)
  • Tumors that grow along the nerve leading from the eye to the brain (the optic nerve), which may lead to reduced vision or total vision loss
  • High blood pressure
  • Short stature
  • An unusually large head
  • Skeletal abnormalities such as an abnormal curvature of the spine (scoliosis)
  • Learning disabilities and attention deficit hyperactivity disorder (ADHD)

The article details something of a chance meeting between University of Wisconsin colleagues Charles Konsitzke and Dhanu Shanmuganayagam at a university event, where Shanmuganayagam shared that he ran a facility that rears miniature pigs, which are genetically engineered to carry mutations found in human genetic disorders.

This sparked the idea for Konsitzke, whose son has NF1.

When studying diseases, scientists often turn to laboratory animals like mice and zebrafish. But those animals – and the other usual lab animals – aren’t a good fit for NF-1. They’re too small, and they don’t react in the same way to the mutations that cause the disease in humans.

For example, studies using mice suggested that a drug called lovastatin might help address learning issues related to NF-1. But when the drug was tested on actual children, in a large clinical trial, it did nothing.

So to better understand NF-1, Konsitzke learned, you need a species that’s closer in both size and biology to a person, while still being relatively easy to  study.

Enter the pigs!  

“Pigs closely represent humans,” says Neha Patel, who directs the UW neurofibromatosis clinic. “People with NF-1 have varied cognitive deficits, from severe learning issues to subtle problems. If you imagine studying those in a rat, you’d only get a crude picture of how that translates to humans. But pigs are intellectual animals.”

So you could imagine Konsitzke’s excitement upon learning Shanmuganayagam’s expertise with pigs!

Konsitzke and Shanmuganayagam aren’t just planning to develop pigs that can model the symptoms of NF-1. They want to use the revolutionary gene-editing technique known as CRISPR to create pigs that have the specific mutations of a particular individual.

Each child with NF-1 would get their own personalized piglet, whose version of the NF1 gene matched their own. The pig proxy could be monitored to see how the kid’s condition might progress, especially since pigs mature faster than humans.

[At the moment, people with NF-1] “are their own guinea pigs,” said Konsitze. “It takes years of tests and side effects to find something that works. My son is on a cocktail of four different meds.”

Having that piglet that mirrors the particulars of a person’s condition might make it quicker to narrow down the best treatments. 

While this new approach is still in development  mode – and several issues still need to be worked out – it is quite exciting to be even thinking about it at all.

 


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