On Rare Innovators: Kat Bryant Knudson and Reimagining Collaboration — “It’s Our Table”

Seizures, incorrect diagnoses, and years of unanswered questions shaped Arielle’s journey with autosomal dominant hypocalcemia type 1 (ADH1). ADH1 is a rare genetic condition in which the body is unable to accurately sense blood calcium levels, leading to hypoparathyroidism. Although she grew up aware that her calcium levels were low, she did not receive a formal diagnosis until age 16, when a severe calcium crash led to a seizure and ultimately revealed the underlying cause. Years later, when her young son Sebastian began experiencing seizures, Arielle recognized familiar warning signs of abnormal calcium levels. Despite a known family history of abnormal calcium levels, his symptoms were initially misdiagnosed, resulting in repeated hospital visits and increasing concern, until genetic testing for hypoparathyroidism ultimately confirmed a diagnosis of ADH1. In this episode of On Rare, David Rintell, Head of Patient Advocacy at BridgeBio, and Mandy Rohrig, Senior Director of Patient Advocacy at BridgeBio, speak with Arielle about navigating life with ADH1 and advocating for answers. She shares the realities of managing a condition that can quickly become life-threatening, from muscle spasms and seizures to hospitalizations and kidney complications, while raising a family and pushing for a diagnosis. Her story highlights the importance of persistence, listening to one’s own instincts, and continuing to ask questions when something doesn’t feel right, while  underscoring the power of a family coming together to find answers to a condition that has affected generations. Dr. Scott Adler, Chief Medical Officer of BridgeBio affiliate Calcilytix and a nephrologist, provides a medical overview of ADH1. Abnormal calcium levels can cause muscle spasms, and severe seizures, and painful muscle contractions known as tetany. About 80% of ADH1 cases are usually inherited in an autosomal dominant pattern, meaning they can be passed down from one affected parent. The remaining cases occur spontaneously, with no family history of the condition. ADH1 is currently managed with oral calcium and active vitamin D supplementation, although maintaining stable levels is challenging and may lead to complications over time.  

In this episode of On Rare: Innovators, hosts David Rintell, Head of Patient Advocacy at BridgeBio, and Mandy Rohrig, Senior Director of Patient Advocacy at BridgeBio, speak with Kat Bryant Knudson, Founder and CEO of the Speak Foundation and a leader in the limb-girdle muscular dystrophy (LGMD) community. Diagnosed as a child after experiencing early symptoms of muscle breakdown, Kat spent years searching for answers before receiving a definitive genetic diagnosis. What began as a personal journey to understand her condition evolved into a lifelong commitment to ensuring that no one with LGMD faces that journey alone. From founding the Speak Foundation in an unexpected twist of fate to organizing groundbreaking scientific workshops that bring patients, researchers, industry, and the FDA to the same table, Kat has helped reshape how the LGMD community connects, advocates, and advances research. Guided by the belief that people with lived experience should have the loudest voice in the room, Kat continues to innovate on behalf of a diverse and growing rare disease community. Kat’s story is a reminder that progress begins with connection, shared experience, and the courage to speak up. Pantene is a third-party trademark. BridgeBio is not affiliated with or endorsed by Pantene or Procter & Gamble, and this reference is for storytelling purposes only.

In our 2025 year-in-review episode, On Rare reflects on a year filled with meaningful conversations and powerful storytelling. Joined by David Rintell, Head of Patient Advocacy at BridgeBio, and Mandy Rohrig, Senior Director of Patient Advocacy at BridgeBio, we revisit moments that moved us, challenged us, and reaffirmed the importance of listening to the voices of rare disease communities. This year also marked an exciting milestone with the launch of On Rare: Innovators, a new series spotlighting leaders, including patients, caregivers, scientists, and advocates, who are taking action to transform the lives of those impacted by rare disease. We are deeply grateful to all of our guests and listeners for being part of the 2025 journey. Subscribe to continue learning with us in 2026.

En el episodio inaugural de On Rare: Innovadores, una nueva serie derivada de On Rare de BridgeBio, los presentadores David Rintell, director de abogacía de pacientes de BridgeBio, y Mandy Rohrig, directora sénior de abogacía de pacientes de BridgeBio, presentan a los oyentes a las personas que están transformando la comunidad de enfermedades raras a través de la defensa de los derechos, la compasión y la acción. La serie comienza en Gijón, España, con Carmen Alonso, fundadora de la Fundación ALPE, quien ha dedicado su vida a mejorar la atención y construir una comunidad para las personas y familias que viven con acondroplasia. Lo que comenzó como el viaje personal de Carmen, una madre que buscaba información y apoyo, se convirtió en una red internacional que ha transformado la comprensión y el manejo de la acondroplasia y otras displasias esqueléticas. Acompañada por su hijo Yago y su colega Fani, Carmen reflexiona sobre las lecciones de amor e inclusión que han guiado su trabajo y la convicción de que "siempre se puede hacer algo". A través de la historia de Carmen, On Rare: Innovators celebra a los líderes cuyas ideas y determinación impulsan el cambio en la ciencia, la defensa de los derechos y la comunidad. Su trabajo nos recuerda que la innovación no se encuentra solo en los laboratorios o las salas de juntas, sino que florece dondequiera que las personas decidan actuar con propósito y corazón.

In this episode of On Rare Innovators, Mandy Rohrig, Senior Director of Patient Advocacy at BridgeBio, and David Rintell, Head of Patient Advocacy at BridgeBio, talk with Nasha Fitter, a parent, entrepreneur, and rare disease leader whose determination was reshaped the day her daughter Amara was diagnosed with FOXG1 syndrome. Drawing on a career defined by bold pivots and purpose-driven problem solving, Nasha is challenging long-held assumptions about what small, rare disease communities can achieve. From building the FOXG1 Research Foundation to co-founding Citizen Health, she has pushed for new models of data, drug development, and patient empowerment. Nasha’s story is a reminder that innovation often begins with a single question: “Who says we can’t do this?”

Greg’s journey with LMNA cardiomyopathy, a rare inherited heart condition, began in high school when he experienced sudden episodes of rapid, irregular heartbeats during track practice. The cause remained a mystery for years, leading to misdiagnoses and untreated disease progression. During that time, Greg faced life-threatening arrhythmias and required several implanted devices before finally receiving a heart transplant. That experience, and the challenges that came before it, ultimately inspired his passion to create change and help others facing the same uncertainty. In this episode of On Rare, David Rintell, Head of Patient Advocacy at BridgeBio, and Mandy Rohrig, Senior Director of Patient Advocacy at BridgeBio, speak with Greg about the long road to diagnosis, the emotional impact of learning he had passed the condition on to his children, and his transformation into an advocate as president of the DCM Foundation. He also shares how his personal experience led to the launch of Everygene, a free genetic testing program for people with cardiomyopathies. Dr. Clayton Beard, Chief Scientific Officer at BridgeBio Gene Therapy, provides a high-level medical overview of LMNA-related dilated cardiomyopathy, a form of heart disease caused by mutations in the LMNA gene that compromise the structural integrity of heart cells and disrupt electrical signaling. He explains how these changes can cause dangerous arrhythmias, weaken the heart muscle, and lead to heart failure, making LMNA cardiomyopathy one of the most severe genetic forms of the condition. Dr. Beard also highlights the importance of early genetic testing for at-risk families, the role of research in improving detection and treatment, and how a better understanding of LMNA can lead to life-saving interventions.

In the inaugural episode of On Rare: Innovators, a new sister series of On Rare from BridgeBio, hosts David Rintell, Head of Patient Advocacy at BridgeBio, and Mandy Rohrig, Senior Director of Patient Advocacy at BridgeBio, introduce listeners to the changemakers reshaping the rare disease community through advocacy, compassion, and action. The series begins in Gijón, Spain with Carmen Alonso, founder and longtime leader of the ALPE Foundation, who has dedicated her life to improving care and building community for people and families living with achondroplasia. What began as Carmen’s personal journey as a mother seeking information and support grew into an international network that has transformed how achondroplasia and other skeletal dysplasia are understood and managed. Joined by her son Yago and longtime colleague Fani , Carmen reflects on the lessons of love and inclusion that have guided her work and the belief that “you can always do something.”   Through Carmen’s story, On Rare: Innovators celebrates leaders whose ideas and determination drive change across science, advocacy, and community. Their work reminds us that innovation isn’t only found in laboratories or boardrooms—it thrives wherever people choose to act with purpose and heart.  

Before she turned eight, Cerys had already faced two diagnoses, only one of which she truly understood. While being diagnosed with celiac disease as a child, unusually high CK levels in her blood pointed to a deeper issue: limb-girdle muscular dystrophy type 2I/R9 (LGMD2I/R9). In this episode of On Rare, David Rintell, Head of Patient Advocacy at BridgeBio, and Mandy Rohrig, Senior Director of Patient Advocacy at BridgeBio Gene Therapy, speak with Cerys, a 23-year-old living in Wales, about living with LGMD2I/R9. She shares how she’s navigated symptom progression, adapted to using mobility aids, and discovered the power of telling her story through her podcast, Unbalanced. When Cerys was first diagnosed with LGMD2I/R9 at age seven 7 years old, she didn’t fully understand the diagnosis. Her parents carried the emotional weight, trying to protect her from fear of what was ahead. It wasn’t until her muscle weakness became impossible to ignore, at 12 years old, that the condition began to define her daily life. From navigating stairs and driving to embracing a wheelchair, Cerys has had to adapt physically, emotionally, and socially, all while managing her energy levels so that she can continue to do the activities she loves. She finds strength in the LGMD community and hope in research, representation, and connection. In 2023, she launched Unbalanced to amplify stories like hers because growing up, she didn’t see anyone with a disability who looked like her. Now, she’s determined to be that voice for others. Dr. Anna Talaga, Director of Medical Affairs at ML Bio Solutions (a BridgeBio affiliate), provides a medical overview of LGMD. LGMDs are a group of genetic diseases that cause progressive muscle weakness and wasting, particularly in the shoulders, hips, and thighs. In some people, the heart and respiratory muscles may be impacted. Unlike many genetic conditions that are caused by a mutation in a single gene, LGMD can result from mutations in many different genes because they all affect the same protein complex that supports and stabilizes muscle fibers. LGMD type 2I/R9 (LGMD2I/R9), specifically, is caused by mutations in the FKRP gene, which is critical for maintaining muscle fiber integrity. Diagnosis typically begins with symptoms like difficulty walking, climbing stairs, or standing from a seated position, and is confirmed through genetic testing. LGMD2I/R9 is a progressive disease and there are currently no approved treatments that slow or stop its progression.

Seizures, sleepless nights, and mysterious white patches on his skin marked the beginning of Daniel’s journey with Tuberous Sclerosis Complex (TSC). Diagnosed at age 6, Daniel faced a childhood filled with MRIs, EEGs, and specialist visits, often requiring cross-country travel for coordinated care. In this moving episode of On Rare, David Rintell, Head of Patient Advocacy at BridgeBio, and Mandy Rohrig, Senior Director of Patient Advocacy at BridgeBio Gene Therapy, speak with Daniel, a 31-year-old living in Seattle, about growing up with TSC, the emotional toll of visible symptoms, and the stigma he faced from peers. He reflects on the cognitive and mood impacts of TSC, including OCD and outbursts, and how he often kept to himself to feel more accepted. Today, Daniel is an active advocate in the TSC community, emphasizing the importance of connection, representation, and finding support among those with shared experiences. As he puts it, “You have to find your people.” Che-Wei Chang, Principal Scientist at BridgeBio, presents a medical overview of Tuberous Sclerosis Complex (TSC), a rare genetic disorder marked by seizures and benign tumors throughout the body. TSC results from a spontaneous mutation in a single copy of the TSC1 or TSC2 gene, which normally inhibit mTOR, an enzyme that regulates cell growth. Loss of this inhibition leads to mTOR hyperactivation, leading to abnormal cell proliferation and tumors in the brain, kidneys, skin, and other organs. Diagnosis typically involves identifying tubers in the brain along with tumors in other organs and is confirmed through genetic testing. Treatments include mTOR inhibitors, which are effective against many TSC-related tumors, and anti-seizure medications, although drug resistance is common.

Katie and Allie’s story began in childhood with unexplained clumsiness and subtle symptoms that intensified over time. After years of searching for answers, Katie was diagnosed with late-onset Tay-Sachs (LOTS), a rare neurodegenerative disease. Further testing confirmed her twin sister Allie’s diagnosis as well. Despite facing daily challenges ranging from mobility issues to emotional strain, the sisters have become passionate advocates, raising over $1 million for research and awareness. With humor, grit, and the support of their family—especially their powerhouse mom—they continue to live fully and inspire the rare disease community. In this moving episode of On Rare, David Rintell, Head of Patient Advocacy at BridgeBio, and Mandy Rohrig, Senior Director of Patient Advocacy at BridgeBio Gene Therapy, speak with Katie and Allie, who share their experience with late-onset Tay-Sachs. The episode explores how Tay-Sachs, typically diagnosed in childhood, can present in adulthood, the emotional toll of navigating a progressive rare disease, and the resilience of a close-knit sibling duo who’ve turned advocacy into action.   Diana Jussila, Director of Family Services at the National Tay-Sachs & Allied Diseases Association (NTSAD), provides essential insights into late-onset Tay-Sachs disease, a rare, progressive, neurodegenerative condition caused by mutations in the HEXA gene leading to deficiency of the Hex A enzyme. Without this enzyme, toxic substances accumulate in the brain and spinal cord, resulting in symptoms like muscle weakness, balance issues, speech difficulties, and psychiatric challenges. With no approved treatments and only supportive care available, community connection, advocacy, and ongoing research are vital lifelines for those living with late-onset Tay-Sachs disease.