Pingelap

A tiny Micronesian island atoll with a population of 250 people, famous for its high prevalence of Achromatopsia. The island was the main setting of the very popular non-fiction book by Oliver Sacks: Island of the Colorblind.

Its prevalence on the island has been traced back to a population bottleneck in 1775 after a catastrophic typhoon swept through the island, leaving only about 20 survivors. One of these, Doahkaesa Mwanenihsed (the ruler at that time), is now believed to have been a carrier for the allele that causes Achromatopsia. Since achromatopsia is an autosomal recessive disorder, inbreeding between the descendants of Doahkaesa Mwanenised would result in an increased recessive allele frequency. By the sixth generation after the typhoon, about 5% of the population was Achromatic.