When Jessica Karnes was a kid, she was told she was no longer allowed to eat chicken nuggets. As a self-proclaimed lifelong picky eater—and a four-and-a-half-year-old at the time—this was a hard fate to process. She also had to stop eating most animal products, beans, nuts, and natural sources of protein. Even something as innocuous as bread was dangerous. We met Jessica at HCU Network America’s conference in Indianapolis, and she shared her winding HCU journey with us.
The quest for a diagnosis
This new diet wasn’t fun, but it was doctor-issued. Ever since Jessica had stopped breastfeeding, she’d started exhibiting symptoms that concerned her parents. The family went from doctor to doctor, searching for answers, until they tried the Beaumont Developmental Center. When her mother mentioned the smell of her urine, the doctor said that Jessica likely had cystinuria or homocystinuria. They sent out a test, which confirmed that Jessica had one of the two conditions. They referred the family to University of Michigan, where doctors conducted a skin biopsy and diagnosed Jessica with homocystinuria—a diagnosis that was, as Jessica explained, “We realized things were going to change. We had to go to appointments. We had to go to specialists all the time, especially at first.”
About Homocystinuria (HCU)
Homocystinuria (HCU) is a rare metabolic disorder. It’s passed down genetically. While it’s estimated that in the US, one in 250 people are carriers, because it’s autosomal recessive, only about one in 300,000-400,000 people have it. People with HCU can’t process particular amino acids present in most food protein, and as a result, have high homocysteine levels. This can cause a variety of symptoms including early osteoporosis, near-sightedness, lens dislocation, developmental delay, learning problems, and blood-clotting. It can be fatal without adequate treatment. There are different types of HCU, and the symptoms exist on a spectrum. Not everyone with the disorder will show all symptoms.
HCU is treated with a variety of medications—and an extremely low-protein diet, supplemented by a protein formula (or, less frequently, tablets) with the problematic amino acids removed. A low protein diet doesn’t just mean no meat or Greek yogurt. Foods that generally aren’t seen as protein-rich, like corn or green peas, can still pose a risk HCU patients. While treatments help, there are still unmet needs. Additionally, the diet is hard to comply to. There are currently clinical trials developing new treatments. Jessica is enrolled in one of the clinical trials, OT-58.
Eating with HCU
There are foods that are made with low-protein patient in mind. Jessica names Taste Connections, a HCU-friendly baking mix company started by the mother of an HCU patient, as one of her favorites. Still, it’s hard to navigate eating when you’re out at school or with friends. Jessica created an arrangement with the dining hall when she went to college, and often orders French fries when she’s out with friends. For years, she would tell everyone that she just had a food allergy, because it was easier than explaining what HCU is. In more recent years, she’s stopped doing this. She explains to people that her body doesn’t metabolize an amino acid, which is actually a pretty different thing. She wishes more people understood the distinction, and also wants people to understand how rare HCU is. Because it has a small patient population, the community is spread out and it’s hard to get together. Jessica is involved with the HCU Network of America, which provides resources and community to other HCU patients.
Ideally, HCU is diagnosed early on, after newborn screening. Newborn screening tests infants in their first 24-48 hours, and identifies certain disorders they may have. It’s much easier to manage HCU if it’s been detected at birth. Unfortunately, HCU newborn screening misses a high proportion of people with the disorder. Jessica said that she thinks her symptoms would have been easier if she had been diagnosed at birth.
Formula struggles
Jessica started taking formula after her diagnosis. Formula is not, by the way, the equivalent to a grocery store protein drink. It’s bitter with a strong taste—or as Jessica explains it: “It’s nasty. That’s the only word I can think of.”
Her parents tried every trick in the book to mix it into something palatable. They tried juices, and even chocolate syrup– which, Jessica added, is pushing it for someone with HCU. Even chocolate syrup has some protein in it. She tried different formulas, some of which she liked better than others. However, when she was older, she was also diagnosed with diabetes and had to begin limiting her carb intake. For a while, she went off formula entirely. With doctor permission, she started eating foods that had protein in it, as she tried to balance between the conflicting needs of her conditions. Recently, she’s started taking tablets in place of formula. She takes forty-five tablets throughout the day. She has many different doctors—from her endocrinologist to her metabolic team
Support and Clinical Trials
She also started the clinical trial she’s participating in, OT-58, at the end of this past January. The trial is in Indianapolis, but Jessica lives in Michigan—which means she has to travel five and a half hours both directions. For the first six weeks, she had to make the trip every week. The following six weeks, she only went once, but a nurse visited her weekly. She received injections, but because the study is double-blind, she doesn’t know whether she’s on the placebo or the treatment. One of the cohorts of the study who just started are receiving the injection twice a week, as opposed to receiving two injections once a week.
Although the trial involves a lot of work and uncertainty, Jessica says, “Sometimes we have to be the guinea pigs.”
Jessica believes support is key for anybody in a rare disease community. She’s attended different conferences with NORD and the HCU Network. Social media also has helped her expand her support as well. If she could talk to someone who was just diagnosed with HCU, or who has a child who was just diagnosed, she would let them know: it is possible to live a normal life. You or your child won’t just be stuck at home. Jessica went away for college and earned a Bachelor’s degree in social work. She says, “You have to stay on top of the nutritional part and medical part,” but it’s doable. She also encourages patients and families to ask the doctor a lot of questions, and to not feel afraid of doing so. Having HCU is a huge adjustment, but Jessica and others involved in the HCU Network and clinical trials, are helping pave the way to better treatment options and more comprehensive support.
