Title: When Your Child Is the Zebra: A Mother’s Quest for a Glycogen Storage Disease Type IV Diagnosis

By: Amber Robertson, Patient Advocate

In the medical realm, there’s a well-known saying that directs clinical judgment: “When hoofbeats are heard, think of horses rather than zebras.” Physicians are trained to initially seek out common causes. But what if your child is the “zebra”—a rare and frequently disregarded case that resists simple diagnosis?

This is the path I have traversed with my daughter, Mia.

▾ A Mother’s Instinct

From before Mia’s birth, I had a feeling that something was amiss. Unlike with my earlier pregnancies, Mia had minimal movement in the womb. Even though my obstetrician assured me that all was well, I couldn’t shake the intuition that something was off. When Mia was born, my apprehensions grew—she exhibited multiple red flags: a skin tag on her ear, neck tightness, a fractured growth plate, and respiratory difficulties that necessitated a NICU admission.

Initially, doctors suspected Turner syndrome. We endured a torturous three-month wait, only to find out that the results were negative. Although we felt a fleeting sense of relief, Mia’s symptoms persisted without explanation. She was not achieving essential developmental milestones and did not pass her newborn hearing test in her right ear.

Despite the pediatrician’s reassurances, I knew deep down that postponing her reevaluation until the age of two could result in Mia missing out on vital care. I resigned from my 11-year job to dedicate myself to seeking answers and caring for my daughter full-time.

▾ The Journey to Diagnosis

It was only after expressing my concerns to Mia’s orthopedic surgeon at UC Davis that my worries were finally acknowledged. She facilitated a referral to neurology and genetics specialists. Mia was hospitalized due to failure to thrive, and an MRI uncovered developmental irregularities in her brain—an underdeveloped cerebellum and a thin corpus callosum.

Soon after, we were expedited to the genetics team. Another month of anticipation ensued, but this time, we received clarity: Mia was diagnosed with Glycogen Storage Disease Type IV (GSD IV), a rare inherited metabolic disorder.

▾ Comprehending GSD IV

GSD IV results from mutations in the GBE1 gene. The body lacks adequate glycogen branching enzyme, resulting in abnormal glycogen accumulation in organs like the liver, muscles, and brain. These defective glycogen molecules accumulate into polyglucosan bodies, which the body struggles to eliminate.

The manifestations of GSD IV vary widely. In pediatric cases, the disorder can lead to issues from in utero through adolescence, presenting diverse levels of liver, muscle, heart, and neurological involvement. On the other hand, the adult variant—Adult Polyglucosan Body Disease (APBD)—usually appears with progressive neurological symptoms in middle adulthood.

Mia’s case diverged from the norm. With primarily neuromuscular involvement and no liver issues so far, her symptoms provided fresh insights into the diversity of this ultra-rare condition.

▾ Confronting Everyday Trials

Even with a diagnosis confirmed, our challenges persisted. Acquiring medical equipment such as CPAP machines, specialized feeding chairs, scoliosis braces, and an electric wheelchair has been a lengthy ordeal rife with bureaucratic obstacles. A significant amount of my time is spent on research and advocacy—responsibilities that shouldn’t rest entirely on families, particularly when the stakes are this high.

Geography presents its own set of obstacles. Our family endures grueling trips—an eight-hour round trip to the hospital in Sacramento and three hours for therapy sessions in Redding. Due to the limited number of specialists knowledgeable about metabolic disorders such as GSD IV, most of Mia’s therapy occurs virtually, which hampers its effectiveness.

▾ Navigating the Uncertainty

The most challenging aspect continues to be the unpredictability. We are unsure if Mia will walk. We don’t know if her liver will deteriorate. We are uncertain about what her future holds or how long that future might last. Much of my understanding stems not from textbooks or medical professionals, but from conversations with other families traveling this solitary road. Together, we are cultivating the knowledge that the medical community lacks.

▾ Advocacy and the Strength of Community

As Mia’s mother, I’ve taken on the roles of her voice, advocate, therapist, and case manager. I have also expanded my advocacy efforts. Locally, I’ve begun collaborating with schools to promote wheelchair accessibility. Already, we have modified the playground planned for Mia’s future kindergarten. More adaptations are in the pipeline to ensure that inclusion is standard practice, not an exception.

In May 2023, we journeyed across the country to meet with Dr. Priya Kishnani and Dr. Rebecca Koch at Duke University. Mia participated in their Natural History Study for GSD IV and APBD—contributing valuable data that may influence future treatment approaches.

Dr. Koch reflected on her meeting with Mia and the impression she’s