Bigger human genome pool uncovers more rare variants
Thanks to powerful computational tools developed at Simon Fraser University, more than 100 scientists from around the world have genetically mapped the largest and most varied number of human genomes to date.
The scientists, including SFU doctoral students Iman Hajirasouliha and Fereydoun Hormozdiari (recently graduated), sequenced and analyzed a pool of 1092 human genomes. Hormozdiari is now pursuing postdoctoral studies at the University of Washington.
The scientists sequenced the genomes of individuals from 14 different populations (five from Europe; three from Africa; three from East Asia; three from the Americas). The researchers used computational tools developed in Cenk Sahinalp’s lab to discover many variants in those genomes. Sahinalp, who is Hajirasouliha’s and Hormozdiari’s doctoral supervisor, is a professor in SFU’s School of Computing Science.
In the largest previous study, which also involved Hajirasouliha and Hormozdiari in Sahinalp’s lab, scientists sequenced the genomes of 185 people selected from an original pool of 1,000 human genomes.
Delving into a larger and more varied pool of genetic information has enabled the scientists to discover more numerous and rarer genetic variations than previously known.
Their findings have just been published in the Nature journal article An integrated map of genetic variation from 1,092 human genomes now online.
“Rare genetic variants are indeed very important because on the evolutionary scale, they occurred most recently,” explains Hajirasouliha. “Their patterns of sharing among different individuals can reveal aspects of population history. They are also very important in disease association studies, which aim often today to associate rare variants with diseases of genomic origin, such as autism and cancer.”
The researchers have yet to figure out what their latest genetic cache means in terms of population health and diseases. That could take years. They are sifting through 38 million variations in a single nucleotide of DNA and 1.4 million small insertions and deletions and more than 14 thousand larger deletions in DNA sequences.
Hajirasouliha is already looking ahead to the next big project. “I would personally like to see more individuals from more populations being sequenced, with less focus on European populations. I would also like to look for more complex variations,” says the researcher. “This kind of sequencing is extremely important for medical genetic studies in many populations. In fact, there are plans to extend genomic mapping to 1,500 more people representing 11 new populations.”
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