The genome sequences of 250 Dutch families, the largest such collection of genome sequences from a single country to date, are reported in a paper published online this week in Nature Genetics. The data provide new insights into the human genome and could provide new tools for finding genes that cause disease.

Major differences exist in the types of DNA changes that can occur between populations, and large collections of genome sequences from many countries are needed to find new disease-causing DNA variants.

Paul de Bakker and colleagues sequenced 769 Dutch genomes from 250 groups of parents and offspring. Among their major findings were 7.6 million variants in the genome that had never before been observed. They also found that each person in the study carried, on average, eight rare gene mutations that could lead to disease. These data could also allow researchers to better understand the history of population migration within the Netherlands.