From a Shocking Diagnosis to an International Advocate: Laurence Letreguilly Shares Her GSD IV Journey
By Laurence Letreguilly
October 19, 2025
EDITOR’S NOTE: APBD (the late-onset form of GSD IV) and Andersen Disease (the early-onset form of GSD IV) share the same underlying root cause: changes in the GBE1 gene which result in deficiency of a protein called glycogen branching enzyme (GBE). Deficiency of this protein leads to dysfunctional glycogen storage and metabolism and the build-up of harmful substances called polyglucosan bodies in different tissues. Given that these ultra-rare conditions are essentially different manifestations of the same biochemical problem, this provides a powerful argument for our APBD community and the broader GSD IV community to work together to identify patients and families, build power and strength in numbers, and advance research and therapies.
A special thanks to Elizabeth LeBlanc, our Genetic Counseling Intern from Columbia University’s Department of Genetic Counseling, for drawing out this powerful narrative with Laurence Letreguilly.
When my partner Remi and I welcomed our son Marius into the world in December of 2019, we couldn’t have imagined how our lives would change. In just a few years, I went from receiving a shocking GSD IV diagnosis for my son Marius, through a journey of medical mistrust, to becoming an international advocate for all patients and families impacted by a GSD diagnosis.
From left to right: Laurence, rugby player Antoine Dupont, Marius, and Remi
After a normal pregnancy, Marius’ birth was unexpectedly traumatic. I underwent an emergency C-section due to insufficient amniotic fluid, and Marius was immediately taken away by the care team because he was having difficulty breathing. The next few days were filled with challenges for Marius and the gut-wrenching feeling of not knowing what was wrong. Instead of being congratulated for welcoming a beautiful baby into the world, Remi and I were receiving information that was worrying and the doctors didn’t have answers. Our son’s body position was not normal and it appeared that his hips were dislocated (which we learned later that they weren’t). Even after we brought Marius home, he struggled to gain weight, and as first-time parents, we had nothing to compare this journey with. The uncertainty continued and so did the endless visits with the doctors.
Marius’ doctors referred us to a geneticist who ordered the review of a small panel of genes. The test results came back with no specific answers, so whole genome sequencing was the next investigative step. The results came back, and my son received the Glycogen Storage Disease Type IV (GSD IV) diagnosis at the age of 2. Our questions shifted to, “What does this mean for Maruis’ future? Is his life at risk? How do we help him?”
GSD IV is an ultra-rare genetic disorder caused by changes in the GBE1 gene and is inherited in an autosomal recessive manner. I’ve learned that it is a disease spectrum, with early-onset and adult-onset presentations which occur when the body has low activity of a specific protein needed to make glycogen, a stored form ofenergy. The abnormal glycogen does not have the correct shape, causing it to build up into clumps called polyglucosan bodies. The early-onset (or “pediatric”) form of GSD IV presents anywhere between infancy and adolescence and causes a range of liver, neurologic, muscle, and heart manifestations. The adult-onset form of GSD IV (or Adult Polyglucosan Body Disease) presents as early as in the mid-30s with primarily neurologic and muscle manifestations.
The first specialist we saw in Paris told us that Marius would need a liver transplant; we were devastated. However, it seemed like the doctor lacked familiarity with the disease and hadn’t seen his prior medical charts; so, we did not have confidence in working with her. Consequently, we got another specialist involved.
Eventually, we found a more knowledgeable and compassionate team of specialists in Bordeaux. There, we learned that Marius did not need a transplant. With this news, we could focus on managing the condition and helping Marius thrive. We now have a deep understanding that parents of children with rare diseases have to become parent advocates as well as experts themselves.
I found that it takes time as a parent to come to terms with a rare disease diagnosis. It took Remi and me a full year after learning the diagnosis to start to reach out to the GSD community. In 2023, I contacted the Association Francophones des Glycogenoses (AFG), a patient advocacy organization for GSDs in France. At the AFG’s first family weekend gathering that we attended, no researcher mentioned advancing GSD IV therapies, and there were no families who shared our son’s diagnosis. We were the first! It made me question, “Who is looking out for us?”
Through the AFG and a private Facebook Group for GSD IV Families, we connected with two families in France. Through the AFG, I learned about the APBD Research Foundation’s 2024 Focus Group for APBD and Early-onset GSD IV. Being a part of this group has led to even more connections and opportunities.
In October 2024, I accepted an invitation to join the AFG’s Board of Directors. Because GSD IV is ultra-rare, one of the most important things I can do as a mother is to share my son’s journey and make sure that others see him as a child and not just a medical case. My advocacy helps drive research, provide support, and ensure that no GSD family walks this journey alone.
Marius is five and a half years old now and is obsessed with sports. He doesn’t walk, but that doesn’t stop him. Inspired by his love for rugby, he created his own version of the game called ‘Sitting Rugby.’ With the help of AFM Téléthon and other organizations, Marius has met renowned professional rugby players like Antoine Dupont, Thibaud Flament, and Maxime Lamothe. These experiences have been extremely motivating for Marius, allowing him to continue being active, which is the number one thing that helps him progress.
Marius’s journey is a powerful reminder that living with a disability is an invitation to find creative ways to adapt the things you love to fit your world. Marius’ joy, determination, and resilience shine through in everything he does. Whether he’s swimming, playing, or creating his own games, Marius fills each day with laughter. If there is one thing I want anyone reading our story to know it is that my son is wonderful.