Genes are specific sequences of DNA base pairs that contain the code each cell needs to make proteins. Alleles are different forms of the same gene having different base pair sequences an individual inherits two alleles for each gene, one from each parent. This allowed them to determine with a high level of accuracy which alleles were present in each individual. Based on the variants they had discovered in the larger group, they projected the sequence of genotyped participants' whole genomes based on long stretches of DNA sequence that were similar to the smaller group of fully sequenced participants.
The researchers then examined 104,220 Icelanders-about a third of the country's population-who had specific parts of their DNA sequenced with a technique known as a genotype array (which looks for the presence of different SNPs, rather than sequencing that individual's entire genome). They found about 20 million SNPs (single nucleotide polymorphisms, individual points in the DNA where the base pair of one person differs from that of another person at the same location), and 1.5 million insertions and deletions (where a stretch of DNA base pairs has been added to, or removed, from the DNA of a specific person.) Having fully sequenced 2,636 Icelanders, the researchers compared the genomes of the individuals and looked for areas where they differed from each other. (To avoid awkward situations like accidentally dating your cousin, Íslendingabók was recently connected to an application that quickly identifies the degree of relatedness between any two people.)Īdditionally, electronic medical records, part of the country's national healthcare system, easily link genotype (the sequence of bases that make up a person's DNA) to phenotype (the observable characteristics of a person). In population genomics, this is called the founder effect, in which the lack of diversity limits the number of genomic variants (differences between people), and allows usually rare variants to become common enough in the population to be more easily noticed and studied.
Data about the population's genealogy has been extensively recorded since 740 AD, and sits in an accessible database called Íslendingabók or book of Icelanders. The island's relative isolation has resulted in a population of approximately 320,000 that is almost entirely descended from a single family tree. Iceland is well-suited for genomics research for a few reasons. The March Genome Advance of the Month focuses on some of the interesting results published as a collection of papers in last month's Nature Genetics. Stefánsson is also chief executive officer of deCODE genetics, a biopharmaceutical company in Reykjavík, Iceland. Last month, Kári Stefánsson, M.D., Daníel Fannar Guðbjartsson, Ph.D., and their research team at deCODE genetics announced findings based on the whole genome sequence information of 2,636 Icelanders and the genotypic information of 104,220 other Icelanders. Most people do not, however, think of large-scale genomic studies.īut maybe they should. Iceland study provides insights into disease, paves way for large-scale genomic studies By Yekaterina Vaydylevichįor some, Iceland conjures thoughts of geothermal spas like the Blue Lagoon, moonlike landscapes and literary sagas peopled with Huldufólk, elfin creatures.
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