Coryssa Barnes, of Henderson, N.C., welcomed her first child, Ezra, in 2020. At four months old, he was unable to sit without support. As time went on, he failed to reach other developmental milestones, prompting his worried parents to consult several medical experts.
"Something was not, you know, not clicking how it's supposed to," said Barnes through tears. "The doctors all came back to us to say that they didn't have a diagnosis. We had a mix of anxiety and nerves because you don't want anything to be wrong with your kid."
Following a year of unknowns and anxiety, Ezra was officially diagnosed at UNC Health. He has a rare neurodevelopmental disorder known as CTNNB1 syndrome that was first described in 2012. It results from alterations in the CTNNB1 gene and is distinguished by developmental delays, intellectual disability, and speech impairment.
Ezra was one of the first patients in the UNC Health system to be diagnosed with CTNNB1. His family is one of many who have had to navigate the long and complex process of receiving a rare disease diagnosis, often referred to as the "diagnostic odyssey."
Melissa Haendel, PhD, a distinguished professor of genetics at the UNC School of Medicine, and collaborators at the Monarch Initiative are helping to improve the diagnostic odyssey for rare disease patients. In partnership with rare disease expert organizations, Monarch has coordinated the Mondo Disease Ontology (Mondo), which aims to harmonize fragmented and hard to identify rare disease knowledge.
Melissa Haendel, PhD, FACMI
"Physicians are challenged to diagnose patients with very rare diseases, so-called 'zebras' because they are so rare," said Haendel, who is an expert on precision health and translational informatics. "This makes running the right test and identifying the best treatment for their patients especially difficult. Mondo expedites this process by gathering fragmented rare disease knowledge from around the world and associating it with one simple diagnostic code that will help patients get on the right path earlier."
The Challenge for Rare Disease Patients and their Providers
Rare diseases are challenging to diagnose due to scattered and inconsistent information across medical databases. Without quick and easy access to rare disease knowledge, physicians may give delayed or incorrect diagnoses. This is especially a concern for those in rural or primary care settings who are not experts in rare and genetic disease.
Haendel, M., McMurry, J., & Sizer, A. (2025). Critical Bottlenecks in Rare Disease Research and Care: A Community Perspective. Zenodo. https://doi.org/10.5281/zenodo.14906644
"Oftentimes, patients with a rare disease never get past their primary care physician," said Haendel. "We can help build clinical decision support tools much further upstream. Together with UNC Health, we aim to help primary care physicians identify symptoms, run tests, and get their patients referred to a specialist as soon as possible."
Medical databases across the world have different definitions and classifications for conditions, leading to inconsistent terminology for rare diseases. For example, "CTNNB1 syndrome" might be called "CTNNB1-related intellectual disability" in one database and "severe intellectual disability-progressive spastic diplegia syndrome" in another, making it even more difficult to track, diagnose, and research these conditions.
"It's like a big hairball that we have to disentangle," said Haendel. "Everyone was chipping away at little pieces of documenting diseases across academia and in medicine. We wanted to make it possible to have a single coding system in the EHR for rare diseases to integrate fragmented communities of resources."
How Mondo Facilitates More Rapid Diagnosis
Mondo works by consolidating rare disease knowledge and terminology from multiple expert medical databases in an AI-friendly way, including ClinGen, Orphanet, International Classification of Diseases (ICD), and OMIM, into one Mondo "code."
Upon diagnosis, the code is added to the patient's electronic health record to help other physicians and researchers define, track, pay for, and research rare diseases. Of the millions of rare disease patients globally, most do not have an ICD code or diagnosis. Mondo introduces nearly 5,000 new rare disease codes and updates more than 25,000 related disease codes in the Epic system.
"I've always said that having a rare disease diagnosis is like finally having a name," said Haendel. "And if the health system can't count rare diseases through coding, then rare disease patients won't count. And they deserve to be heard and seen, no matter how rare the condition."
Securing a new ICD code is an arduous process that takes years, demanding substantial effort, and community coordination of patient groups, which do not exist for every rare disease. Given the heavy caregiving responsibilities such groups already face, a systematic approach like Mondo is vital for streaming their care.
tislab.org/oopd
With help from patient advocacy groups CTNNB1 Connect and Cure and the Consortium for Outcome Measures and Biomarkers for Neurodevelopmental Disorders (COMBINEDBrain), CTNNB1 syndrome was finally "given an EHR name" in the International Classification of Diseases, Tenth Revision, Clinical Modification, or the ICD-10-CM.
"Having the correct diagnosis is everything," said Barnes. "If we didn't push for a diagnosis, we would have missed out on an opportunity to know more about his syndrome and the best steps to take in terms of resources, appointments, decisions, specialties, and medications."
The Barnes family's experience is far from unique. Across the rare disease community, patients spend years cycling through the medical system without a diagnosis or an EHR code. This leaves physicians and patients in a silo, limiting their ability to find the treatments and community they need. Mondo aims to change this narrative.
Mondo will bring the clarity of rare disease diagnosis much sooner for thousands of rare disease patients. In collaboration with IMO Health, Epic EHR systems now have the ability to use the Mondo code for conditions like CTNNB1 syndrome. In Ezra's case, the Mondo code, MONDO:0014035, will string together his health data and streamline his care for years to come.
A Diagnosis Brings Community and Support
Now five years going on six, Ezra, who is non-verbal and requires mobility devices, continues to flourish in his own unique way.
"It's really just inspiring to watch this little kid use his own augmentative and alternative communication (AAC) device, when he wants to," said Barnes with a chuckle. "He's a very bright boy and he can identify shapes and colors and numbers now."
The Barnes family. Credit: Coryssa Barnes.
After finding a diagnosis for Ezra, Barnes found a home within the rare disease online community. She first built rapport with families on a private CTNNB1 Facebook page, where she learned more about research news, specialist recommendations, family advice, and other perspectives.
Barnes would like other families to stay positive and to always remember that there are other families going through the same or similar rare disease experience.
"I really think it's important for people to find their people, especially in the rare disease community," said Barnes. "It is such a different world and it's hard to relate to people who don't get it."
Thanks to Mondo, other children and adults will be given an EHR name, giving them quick access to treatments, research, and a community of others who understand what they're going through.
The Mondo Disease Ontology was primarily funded by the National Institute of Health Office of Research Infrastructure Program and the National Human Genome Research Institute grant numbers 5R24OD011883 and 5RM1HG010860. The Monarch Initiative is an international organization led by UNC, Lawrence Berkeley National Laboratory, the European Bioinformatics Institute, and Queen Mary University of London.
