Isabel “Isa” Stenzel Byrnes (1972-2023) lived much longer and better than anyone expected.

Born with cystic fibrosis, Isa (and her identical twin sister Ana) grew up in Los Angeles when children with CF were not expected to live to adulthood. Despite frequent hospitalizations and difficulty gaining weight, through a strict regimen of respiratory therapy, the twins succeeded in school, formed a t-shirt painting business, and embraced participating in the southern California cystic fibrosis community.

Isa and Ana moved to the San Francisco Bay Area for their higher education. Isa graduated from Stanford with a B.A. in Human Biology and received Master’s degrees in Social Welfare (Health Specialization) and Public Health (Epidemiology/Biostatistics) from the University of California at Berkeley. Three months before their Stanford graduation, Isa started dating her dorm mate Andrew Byrnes; they were married in 1998 at Stanford Memorial Church.

Despite adherence to a rigorous regimen and improvements to cystic fibrosis therapy, Isa’s health declined in the early 2000s. On February 5, 2004, Isa was on a ventilator in the ICU with a bleak prognosis. Due to the generosity of 18 year old high school senior Xavier Cervantes who had signed up to be an organ donor and suffered a brain injury, and his family, on February 6, 2004, Isa received a life-saving double lung transplant.

Isa made full use of Xavier’s lungs, taking up the bagpipes and performing as a member of the Stewart Tartan Pipes and Drums (now Silicon Valley Pipe Band), and becoming an active swimmer, cyclist, runner, and triathlete, winning dozens of medals across nine Transplant Games of America and a World Transplant Games.

Mindful of the power of storytelling, Isa and Ana wrote “The Power of Two: A Twin Triumph Over Cystic Fibrosis” (Univ. of Missouri Press 2007), which was translated in Japanese and released as “Mirakuru Tsuinzu” (Iwanami Shoten 2009). The book inspired the Oscar-qualified documentary film “The Power of Two” (2011), which screened at 30 film festivals worldwide and won 10 festival awards.

A Licensed Clinical Social Worker, Isa dedicated her career to bereavement care, counseling clients of all ages experiencing grief and loss. She was particularly well-known for developing and coordinating a successful writing through loss program at Mission Hospice and Home Care and leading numerous writing for healing groups for the transplant and cystic fibrosis communities, and at Stanford University.

Among other accolades, Isa was twice named Female Athlete of the Year at the Transplant Games of America, was awarded the Jefferson Community Service Award, the Cystic Fibrosis Foundation Breath of Life Award, and the Cystic Fibrosis Research, Inc. Dave Stuckert Volunteer of the Year Award, and was named a Silicon Valley Woman of Influence by the Silicon Valley Business Journal.

Isa is survived by her husband of 25 years Andrew Byrnes, her parents Reiner and Hatsuko Stenzel, her brother Andreas Ryuta Stenzel, sisters-in-law Chie Yao and Mary Byrnes Schneider, brother-in-law Joe Schneider, her nieces Reese, Chloe and Mia, parents-in-law Margaret and Larry Byrnes, and a large community of extended family and friends.

• NPR/Life Kit (2023)
• The Heart of Hospice Podcast (ep. 277 and 279 (2022) and ep. 16 (2020))
• Therapy Chat with Laura Reagan (2019) (episodes 381 and 382 (replay))
• Welcome to Mission Hospice (2019)
• Good Grief with Cheryl Jones (2015)
• Open to Hope interview (2014)
• TEDx Stanford (2014)
• TEDx Constitution Drive (2013)
• Authors @Google (with Ana; 2009)

© Andrew Byrnes 2025