The Island of the Color Blind



Many individuals first learned of achromatopsia in 1997, when Oliver Sacks published his classic book, Island of the Color Blind. This story beautifully chronicals Oliver Sack's 1994 quest with Knut Nordby and Bob Wasserman to the isolated atol of Pingelap in Micronesia, where 10% of the population have rod monochromatism. This is a condition, so very rare in the rest of the world, that most rod monochromats have never encountered another rod monochromat with the possible exception of a sibling.

We encourage everyone to read this amazing book. You will find links to it in our Books and References section. We have also made links to the six segments of the television documentary, Island of the Color Blind available on YouTube.









An Update on the Pingelapse





In 1775, the typhoon Lengkieki struck the South Pacific Atol of Pingelap, part of the eastern Caroline Islands in Micronesia. Long before the typhoon reached its shore, it is believed that a marooned Irish sailor brought the condition to Pingelap.

The gene has now been identified as CNGB3 on Chromosome 8, the gene for the most common form of rod monochromatism. In the year 2000, researchers from John Hopkins University School of Medicine led by Olof Sundin identified the defect, CNGB3, on chromosome 8 in the affected Pingelapse and published the results in Nature Genetics. The very same gene found on this island is found in those of Irish decent.



Only about twenty islanders survived the storm and the famine that followed. From this “founder population” and the geographic and cultural isolationism, achromatopsia descended to the Pingelapse today. Studies suggest that the condition, called maskun by the Pingelapese, did not occur until the fourth generation after the Typhoon, and all descendents today can be traced back to one survivor, Nahnmwarki Mwanenised, who was the ruler at that time. It is believed that he was the only carrier at the time of the typhoon. This is the reason it took four generations for the autosomal recessive condition to appear.



Today, up to 10% of the population has rod monochromatism. This is a "founders effect" of loss of genetic variation which results when a new population starts from small number of individuals.



Such a high grouping of achromats changes the social dynamics of the condition. In the United States there are less than 10,000 achromats spread among a population of over 300 million. In the US and the rest of the world, rod monochromats live in a world where they never meet another achromat with the exception of a sibling. This isolationism of the condition in the rest of the world creates many problems not found on an island where every person knows about the maskun and what to expect from it.

