Research · Participate
Patient Census
~500
Known Worldwide
GeneReviews, Sept. 2025 — Foundation patient-registry data
How Many People Have ZTTK syndrome?
Approximately 79 individuals with ZTTK syndrome have been documented in peer-reviewed scientific literature — the largest single cohort remains the 52 individuals analyzed by Dingemans et al. in 2022. The foundation's own patient registry, built through global community outreach spanning family networks, an international ambassador program, and partner registries, has identified approximately 500 individuals across dozens of countries.
The gap between the published literature count and the registry count reflects challenges common to ultrarare diseases: limited diagnostic access, particularly outside major academic medical centers, and the relatively recent discovery of ZTTK syndrome in 2016. Many cases likely remain undiagnosed or misdiagnosed.
No formal birth-incidence or population-prevalence study for ZTTK syndrome has been published. What the literature-versus-registry gap does show is that the condition is substantially underdiagnosed — every new registration narrows that gap and sharpens the case researchers and industry can make for investing in ZTTK-specific treatments.
Methodology
The worldwide count reflects individuals with a confirmed SON pathogenic variant identified through the foundation's global community — its contact registry, family network, and international ambassador program — together with Citizen Health and Rare-X enrollments, as reported to GeneReviews (Zhu-Tokita-Takenouchi-Kim Syndrome, initial posting September 25, 2025). The peer-reviewed literature count reflects only individuals included in published cohort studies, most recently Dingemans et al. 2022.
“I think there are many in industry who are actually looking for a condition with, say, a population of a thousand or more individuals.”
Dr. Yu's observation underscores why patient counting is not merely academic. Reaching the threshold where industry sees a viable patient population could unlock the pharmaceutical investment needed to develop targeted ZTTK treatments. Every family that registers moves the community closer to that critical mass.
Why Accurate Counts Matter
Research Recruitment
Every identified individual is a potential participant in natural history studies, registries, and future clinical trials. Researchers need to know where patients are and how to reach them.
Industry Investment
Pharmaceutical companies evaluate patient population size when deciding whether to invest in treatment development. Demonstrating a larger, well-documented community strengthens the case for ZTTK therapies.
Clinical Trial Design
Understanding the size and geographic distribution of the ZTTK population directly informs how clinical trials are structured — from site selection to enrollment targets.
Funding & Advocacy
Accurate patient counts support grant applications, government advocacy for rare disease research funding, and efforts to improve diagnostic access worldwide.
Help Us Count Every SON-Shine
Joining the contact registry takes about two minutes. Your registration helps the foundation understand the true scope of ZTTK worldwide and ensures you receive updates on research opportunities.