Short answer · Medically reviewed summary · Last updated: 2026-04-06
Moyamoya is considered a rare disease, with estimated prevalence rates varying significantly by region, often reported between 0.086 and 3 per 100,000 individuals depending on the population studied. Epidemiological Distribution Because Moyamoya is a progressive cerebrovascular condition, its incidence and prevalence are heavily influenced by ethnicity and geography. The highest prevalence of Moyamoya is observed in East Asian populations, particularly in Japan, where the incidence is estimated at approximately 0.54 to 0.94 per 100,000 people annually.
What is the prevalence of Moyamoya?
Prevalence of Moyamoya: how many people are affected worldwide, differences by sex and region, with sources.
Moyamoya is considered a rare disease, with estimated prevalence rates varying significantly by region, often reported between 0.086 and 3 per 100,000 individuals depending on the population studied.
Epidemiological Distribution
Because Moyamoya is a progressive cerebrovascular condition, its incidence and prevalence are heavily influenced by ethnicity and geography. The highest prevalence of Moyamoya is observed in East Asian populations, particularly in Japan, where the incidence is estimated at approximately 0.54 to 0.94 per 100,000 people annually. In North America and Europe, the disease is significantly rarer, making it a challenging condition for clinicians to diagnose promptly.
Demographics and Onset
Moyamoya exhibits a bimodal age distribution, with peaks occurring in children (typically aged 5–10) and adults (typically aged 30–50). Clinical data suggests a slight female predominance, with a female-to-male ratio of approximately 1.8:1. While the condition affects people of all backgrounds, the stark geographic concentration in Japan, Korea, and China suggests both genetic and environmental factors may contribute to its development.
Challenges in Data and Real-World Insights
Accurate epidemiological data for Moyamoya remains difficult to capture. Many cases likely go undiagnosed until a symptomatic stroke or transient ischemic attack occurs, leading to an underestimation of true prevalence. Furthermore, as diagnostic imaging techniques like MRA and angiography improve, more asymptomatic cases are being identified, which shifts our statistical understanding. At DiseaseMaps.org, our community of 215 members living with Moyamoya provides a vital, real-world perspective that complements clinical literature, highlighting the diverse patient journeys that national registries may miss.
Disclaimer: This information is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.
References
- NIH Genetic and Rare Diseases Information Center (GARD): Moyamoya disease
- Orphanet: Moyamoya disease (ORPHA:587)
- Online Mendelian Inheritance in Man (OMIM): Moyamoya disease 1 (MYMY1)
