United States / Europe < 1% (Typically 0.2% – 0.9%) Less common, often considered an anomaly.
Asia (e.g., Korea, Japan) 4% to 10% Significantly higher, suggesting a founder effect or concentrated genetic trait.
African populations ~4% Higher incidence rates noted in several studies.
The condition is often unilateral (appearing on only one ear), which is the most common presentation. However, roughly 25-50% of cases are bilateral (appearing on both ears). There is a slight, statistically insignificant tendency for it to appear more often on the right ear when unilateral, though studies are inconsistent on this point.
