Researchers at Duke University and the University of São Paulo (Brazil) have published an enlightening case report describing the clinical course and diagnostic odyssey of seven individuals with APBD in the scientific journal Frontiers in Genetics.

Through their work, the researchers described the symptoms of three patients in the US with the deep intronic variant previously identified in 2015. They demonstrated that common genetic testing methods, such as whole exome sequencing, have limitations and that even when a patient undergoes genetic testing, the limitations in the methods can lead to a delay in the diagnosis of APBD. In all three reported patients, a re-analysis of genetic testing was required to identify the genetic variants in the GBE1 gene.

In addition to those three cases, they described four cases of APBD in Brazil. These cases encourage the recognition and evaluation of patients from a broader demographic background and age range. Interestingly, several of these Brazilian patients had genotypes traditionally associated with glycogen storage disease type IV in children. Lastly, the team reported the first use of patient reported outcome measures for patients with APBD. Not only did these questionnaires identify a significant impact to quality of life as a result of the disease, but they helped more easily identify and quantify levels of under-recognized symptoms such as pain and fatigue.

These findings represent a big step for the APBD community. The researchers highlight in this paper that the different symptoms of APBD need to be better recognized and that age of onset can be variable. They also discuss the limitations and challenges related to common genetic testing methods. For individuals suspected of having APBD, ensuring that they receive proper genetic testing is crucial to confirming a diagnosis.

Dr. Priya Kishnani and Dr. Rebecca Koch

Dr. Priya Kishnani, a senior co-author of the paper, shared, “This manuscript underscores the importance and the power of international collaboration. It also emphasizes the importance of understanding the strengths and limitations of genetic tools used. This work highlights that APBD is a spectrum disorder and exists on the glycogen storage disease type IV continuum. We are excited to continue our research on APBD!”

Dr. Rebecca Koch, another senior co-author of the paper, added, “We are very grateful for the participation of these individuals in our natural history study. Because of all our study participants, we are able to better understand and characterize APBD. Having this detailed medical information is critical as we look to improve the care patients receive and guide therapy development.”

Editor’s Note: Research Highlights is an ongoing feature in our newsletter. It is focused on scientific publications of interest to our community. Our thanks to Dr. Rebecca Koch and Dr. Marvin Natowicz for sharing their research with us in the January 2024 edition of our e-newsletter!