Growing up on a farm north of Aurora, Nebraska, Dr. Jennifer Harney could tolerate so little protein, she couldn’t enjoy all of the usual farm fare.
When she went out for pizza, she would order a slice with no meat or cheese. At the coffee shop, she would add a nondairy creamer instead of milk. She ate a lot of fruits and veggies. She also choked down a shakelike formula to supplement her diet. A friend once said it tasted like cat food.
Following such a limited diet was necessary to avoid the ill effects of phenylketonuria. Harney was diagnosed with the rare and serious genetic condition shortly after her birth by the heel-prick blood test given to all newborns in the United States.
Those with the condition, also known as PKU, don’t make the enzyme needed to break down the amino acid phenylalanine, one of the building blocks of protein. Without the diet, the amino acid builds up and can cause serious cognitive impairment. Before the condition was discovered, some affected became severely impaired, requiring wheelchairs or long-term living facilities. While most today avoid the worst effects by maintaining a strict diet, even slipping temporarily can cause symptoms — irritability, lack of focus, headaches.
But about four years ago, Harney began testing a new enzyme therapy as part of a clinical trial headed locally by Dr. William Rizzo, her doctor and a professor of pediatrics at the University of Nebraska Medical Center’s Munroe-Meyer Institute.
Once she ramped up her dosage, she could eat things she had never thought possible: chicken, fish, cheese and some new favorites like seafood and pulled pork. She can travel and enjoy restaurants in new places and grab something from the fridge for lunch at work without having to plan meals for a whole week.
“It has totally altered my world,” Harney said.
Now others with PKU are about to get that same opportunity. The U.S. Food and Drug Administration last month approved the enzyme therapy, called Palynziq, for use by adults with the condition. That means Rizzo and other doctors will be able to start prescribing the treatment, which users inject once a day.
“It is a major advance in this disease, in this field, no doubt about it,” Rizzo said.
Between one in 10,000 and 15,000 people in the United States have PKU.
Christine Brown, executive director of the National PKU Alliance, said the therapy is the first of its kind to get to the root of the problem. “It’s a revolutionary new therapy for adults living with PKU,” she said.
Both of her children, ages 10 and 12, have the condition.
“This new treatment option just gives us so much hope,” Brown said of her family and others in the PKU community.
Rizzo said parents can treat children with PKU effectively through diet. But as those children get older, that control falls apart. Young people can begin to have symptoms, including hyperactivity, poor memory and emotional problems.
He’s also found that most adults don’t follow the diet strictly. When they don’t, they suffer some of the same symptoms. He follows about 60 patients in Nebraska.
Without the therapy, Harney said, she can have about six grams of protein a day. A typical adult consumes between 50 and 60 grams. A cup of milk contains eight grams; a serving of pasta has seven. Even an order of McDonald’s french fries contains three grams.
In addition to fruits, vegetables and formula, which some can take as tablets, people with PKU also can order special foods, such as imitation cheeses made with oils and pasta made with corn or potato starch rather than wheat.
The therapy, she said, will let people get to normal phenylalanine levels, where they can feel better and function better.
The condition also has helped shape Harney’s life in another way. Because of her exposure to the medical world, she became interested in becoming a doctor as far back as elementary school.
Harney, 29, earned her medical degree from UNMC in 2011. After she finishes her residency at UNMC in September, she’ll return to Aurora to practice family medicine and obstetrics.
“It’s a pretty big honor to have the people I grew up with coming to me now for their health care,” she said.
Harney is adjusting to the enzyme therapy, again; she took a break while carrying and nursing her son, Finn, who was born in October.
She’s had some side effects — some hives when she started the therapy the first time, and a few days of joint aches this time.
The therapy can cause others, including headache, nausea and skin reactions. The most serious is a severe allergic reaction called anaphalaxis. So the therapy carries a warning label, and prescribers and patients are required to complete special training. Patients also have to have EpiPens available at all times.
As she’s ramped up her dosage, Harney has increased the protein in her diet. Being able to make one meal, instead of two, as a working mom with a busy schedule figures to be a huge time-saver, especially with the new career she’s looking forward to.
“This truly is going to be life-changing for people with PKU,” she said.