Finnish Bottleneck Concentrated Rare Diseases

In Finland, about one in five people carries a gene defect associated with at least one Finnish heritage disease, and roughly one in 500 children is born affected. The group includes 36 rare genetic disorders that occur more frequently among ethnic Finns because of founder effects and genetic isolation. Researchers partly trace this pattern to a population bottleneck among the ancestors of modern Finns about 4,000 years ago, which may have left only two surviving ancestral male lineages. Because most defects are autosomal recessive, two parents carrying the same mutation have a 1 in 4 chance of having an affected child.

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