Amish folks taking a stroll on a warm day. Photo courtesy of Flickr

Staff Writer

Although the Clinic for Special Children is small and remote, it has been the leading clinic worldwide in research and treatment for patients suffering with certain rare genetic disorders, such as maple syrup urine disease (MSUD).

According to the Children’s Hospital of Philadelphia, MSUD is “a rare inherited disorder caused by the body’s inability to properly process amino acids,” meaning that when patients with MSUD eat foods with protein, their body can’t metabolize it, causing a buildup in the bloodstream. This will lead to brain swelling and eventual death in a baby if left untreated.

There is currently no cure for MSUD, but that could change very soon thanks to the staff at the Clinic for Special Children. 

“We are always looking for a better way to treat these kids,” said Dr. Erik Puffenberger, Lab Director of the Clinic for Special Children. 

Current methods of treating MSUD include a diet heavily restricted in proteins and liver transplants, however none of the existing treatments fix the underlying issue: a gene mutation. 

“All of us at the clinic had really recognized that the existing approaches were good and effective, but there was still lots of room for improvement,” said Karlla Brigatti, Research Operations Director at the Clinic for Special Children.

The clinic started trials of gene replacement therapy, which replaces the mutated gene with one that is complete, curing the patient of the illness. However, this method has never been tested for MSUD before.

The trial went successfully on rats, however, Dr. Puffenberger described their need to move toward larger animals.

“Everybody works on mice… but then we wanted a larger animal model because we wanted to move to humans.”

This part is usually difficult in gene therapy trials and involves artificially creating an animal with the disease. However, some Black Hereford cows naturally have MSUD, and the clinic was lucky enough to get in contact with Don Hardin, the owner of Longview Farms in Iowa, who has many cows with MSUD. He allowed them to travel to his farm and perform gene replacement therapy on the calves.

The first MSUD calf that the clinic attempted to treat passed off birth complications unrelated to the disorder. However, they are currently treating a second calf from Longview Farms at the Cummings School of Veterinary Medicine at Tufts University in Iowa.

“We gave this cow, who we have named Petunia, a gene therapy replacement, and she is still alive a year and a half later… We have shown that we are able to rescue the affected cows without any other therapy, with just the gene therapy, and they do not die,” said Dr. Puffenberger.

The clinic staff is very proud of their work with Petunia, who “represents the largest animal model for any human disease,” according to Brigatti. 

Looking forward, the staff at the Clinic for Special Children hopes to move toward human trials and finally be able to provide their patients with a cure for their disease, rather than a treatment to manage symptoms. Their mission has always been to provide relief for children with debilitating genetic disorders, and now they are one step closer to ending the suffering of those born with MSUD.