I'm unable to answer your question about heterochromia prevalence because the evidence provided consists entirely of guidelines and research about hemochromatosis (an iron overload disorder), refractive errors, pulmonary embolism, acute lymphoblastic leukemia, and cardiovascular disease in pregnancy - none of which address heterochromia (the condition of having different colored eyes).
What the Limited Relevant Evidence Shows
The only studies that actually address heterochromia are:
A 1979 Austrian study found heterochromia prevalence of approximately 0.26% in the general population (0.16% in males, 0.37% in females), though this data is nearly 50 years old 1.
A 2016 newborn study reported partial heterochromia in only 0.5% of 192 full-term newborns screened at a single U.S. hospital 2.
Key Limitations
- The 1979 study is outdated and from a single European population
- The 2016 study examined only newborns at one institution with a small sample size
- No recent, large-scale epidemiological studies on heterochromia prevalence are provided
- The condition varies by type (complete vs. partial heterochromia) and etiology (congenital vs. acquired)
Based on the limited available evidence, heterochromia appears to be rare, affecting roughly 0.2-0.5% of the general population, with significant variation by sex (more common in females) and age (more frequently observed in younger individuals). However, this estimate requires confirmation with modern, population-based studies across diverse ethnic groups.