Original: While normally rare , achromatopsia is very common on the island of Pingelap , a part of the Pohnpei state , Federated States of Micronesia , where it is called maskun : about 1/12 of the population there has it .
Simplified: It occurs almost only on the island of Pingelap , a part of the Pohnpei state in the Federated States of Micronesia .