Child with rare metabolic system disorder finds answers and relief through UTHealth Houston team of experts

The first time Katherine Taylor, then 18 months old, became lethargic and started vomiting, her mom, Amanda, chalked it up to germs bought home from her son, who had just started kindergarten.

But over the next six months, the episodes kept occurring: once a month, then once a week, and then a few times a week. Amanda took her to their pediatrician and was referred to a gastrointestinal specialist, but it took months to see the expert, who ordered tests. Then they were told it would be months more before they could see the specialist again for a possible diagnosis.

Meanwhile, Katherine was getting sicker. Desperate, Amanda searched online and found Melissa Van Arsdall, MD, associate professor with the Department of Pediatrics in McGovern Medical School at UTHealth Houston, who could see Katherine the next week.

Katherine, who had just turned 2, was finally on a journey that would bring answers.

At that first visit, Van Arsdall repeated earlier tests, which showed that Katherine’s liver enzymes were higher than normal. She asked the family to have Katherine’s blood drawn again a few days later for more testing. What she saw had her picking up the phone.

“Dr. Van Arsdall called us herself, which doesn’t happen with a doctor, and told us to immediately take Katherine to the emergency room that night,” Amanda said. “She told me Katherine was going into acute liver failure.”

Once she was at Children’s Memorial Hermann Hospital, a UTHealth Houston team that included Van Arsdall; pediatrician and geneticist Paul Hillman, MD, PhD; and metabolic dietitian Paige Roberts, MS, RD, mobilized to get to the bottom of Katherine’s illness.

The team ordered bloodwork to see if the cause was an underlying metabolic issue. The hint to the underlying problem came back in the form of elevated levels of ammonia in the blood.

Hillman ordered genetic testing, which confirmed it was a metabolic disease: a urea cycle disorder called ornithine transcarbamylase (OTC) deficiency.

“Ammonia is never normal in a child, so the fact it was significantly elevated was an immediate indication that she had a metabolic disorder — an issue with her body’s ability to break down food to create energy,” said Hillman, an assistant professor in the Department of Pediatrics. “In the case of a urea cycle disorder, it’s a protein breakdown problem that leads to elevated levels of ammonia.”

Elevated ammonia can damage the brain, which is why it is so important to get an early diagnosis, control the underlying cause through treatment and diet, and have regular follow-ups and bloodwork.

“Her vomiting was caused by a trigger in her brain telling the body that it needed to get something toxic out,” Hillman said. “Her disease is rare, but with the FDA orphan drug program supporting research and development, there are new oral medications to lower the ammonia, and gene therapy is being actively pursued and investigated.”

Her parents finally had an answer.

“It was scary because it was so serious, but I felt relief because the doctors were confident it could be managed,” Amanda said.

Katherine was prescribed an orally administered medication called glycerol phenylbutyrate, an agent that helps remove the accumulated ammonia in the blood.

She also was placed on a very low protein diet in consultation with Roberts. She educated the family on how diet plays a role in the management of the disease, how to read labels and count protein, and the importance of keeping a food journal. To meet her body’s needs for protein and nutrition, Katherine takes a metabolic formula.

“She gets 10.5 grams of protein per day from food while most kids her age get 35 or more,” Roberts said.

When she was 4 years old, Katherine was also diagnosed with gastroparesis — delayed gastric emptying — which can cause masses of old food to build in the stomach and lead to nausea, vomiting, and obstruction. As a result, she now receives much of her formula through a gastrostomy tube. Amanda says their kitchen is like a compounding pharmacy. The formula must be mixed every day.

“If you didn’t know us well and saw us out, you wouldn’t know that she had this condition,” said Amanda, who is also mom to a son, age 11, and another daughter, 1. “When she goes to a party, she can lick the icing off a cupcake but not have the cupcake itself. We carry the burden of that unseen.”

Now 6, Katherine is “becoming her own little person,” her mom said, taking dance and swimming lessons with ease.

“There are lots of things on the horizon for gene therapy, so we are keeping abreast of those,” Amanda said. “We are always looking for what is new that can help her in the future. We work with her so she can take ownership of her condition.”

Amanda said they have told Katherine about her disorder in age-appropriate ways as she has grown, and she now helps mix her formula. “It’s been great watching her blossom by making friends and getting out there,” Amanda said.

Meanwhile, she has touched those who have known her since she was a toddler.

“She is a very bright, sweet, very sunny little girl despite all of this that is going on with her,” Hillman said.