Severe seizures, nonstop crying, and an exaggerated startle reflex marked the beginning of Elliott’s journey with molybdenum cofactor deficiency type A (MOCD type A), an ultra-rare inherited metabolic disorder that can cause devastating neurological damage shortly after birth. After initially being told that Elliott would likely not survive to school age, his family was offered access to an experimental treatment that changed the course of his life. In this episode of On Rare, David Rintell, Head of Patient Advocacy at BridgeBio, and Mandy Rohrig, Senior Director of Patient Advocacy at BridgeBio, travel to England to meet Elliott and his family and hear how they navigated diagnosis, uncertainty, and hope after already experiencing the heartbreaking loss of another child. Geoff and Lucy, Elliott’s parents, reflect on the emotional toll of diagnosis, the realities of managing complex medical care at home, and the joy of watching Elliott grow, attend mainstream school, and live life alongside his siblings. Their story highlights the importance of early diagnosis, caregiver resilience, and the life-changing impact of treatment for rare disease families.

Dr. Günter Schwarz, Professor of Biochemistry at the University of Cologne and a leading expert in MOCD, provides a medical overview of the condition. MOCD is a rare inherited metabolic disorder caused by the body’s inability to produce molybdenum cofactor, which is required for several critical enzymes to function properly. Without it, toxic sulfite builds up in the body, particularly in the brain, leading to severe seizures, neurological injury, and often early death. Dr. Schwarz explains how the condition is inherited, why symptoms begin so early in life, and how targeted treatment can dramatically alter outcomes when started quickly after diagnosis.

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.