Pedigree structure and kinship measurements of a mid-Michigan community: a new North American population isolate identified.

Previous studies identified a cluster of individuals with an autosomal recessive form of deafness that reside in a small region of mid-Michigan. We hypothesized that affected members from this community descend from a defined founder population. Using public records and personal interviews, we constructed a genealogical database that includes the affected individuals and their extended families as descendants of 461 settlers who emigrated from the Eifel region of Germany between 1836 and 1875. The genealogical database represents a 13-generation pedigree that includes 27,747 descendants of these settlers. Among these descendants, 13,784 are presumed living. Many of the extant descendants reside in a 90-square-mile area, and 52% were born to parents who share at least one common ancestor. Among those born to related parents, the median kinship coefficient is 3.7 × 10(-3). While the pedigree contains 2,510 founders, 344 of the 461 settlers accounted for 67% of the genome in the extant population. These data suggest that we identified a new population isolate in North America and that, as demonstrated for congenital hearing loss, this rural mid-Michigan community is a new resource to discover heritable factors that contribute to common health-related conditions.