Historical Migration revealed through a Case of Autosomal Dominant Alzheimer's Disease.

With the increasing geopolitical instability and environmental devastation occurring across the globe, human migration is increasing. We report a case that illustrates a migration pattern seen a century ago that is currently in the process of repeating itself. Using information from a neuropathological examination, genetic analyses, and historical sources, we linked a patient with autosomal dominant Alzheimer's disease in Hawai'i with her ancestors in Puerto Rico. In this patient we identified the G206A PSEN1 mutation, previously identified as being linked to a founder effect from Puerto Rico. At the turn of the twentieth century, due to devastating hurricanes in Puerto Rico and the island's new status as a possession of the United States, over 5,000 Puerto Ricans, including the grandparents of our patient, migrated to Hawai'i. This short-term but historic migration has resulted in a significant population of Puerto Ricans in Hawai'i, today. As physicians we sometimes have the opportunity and privilege, through the patients who come to us for help, to be indirect witnesses to such historical events and movements. These occurrences can inform the present and also portend future developments in this rapidly changing world.