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Tohoku U. team releases 1st full genome model reflecting unique Japan DNA sequences

TOKYO -- A team at Tohoku University has created a model genome covering all DNA base sequences unique to Japanese people, and released it online on Feb. 25.

Previous human genome models had not comprehensively covered DNA sequences seen only in Japan, presenting difficulties for researchers. The university's JG1 Japanese reference genome will clear away those problems and allow more accurate research into the genomes of Japanese people and aid development of medical treatments tailored to individual patients.

When trying to determine the cause of a rare disease, doctors need to hunt down possible mutations in the patient's DNA that could be at the root of their condition. To do that, they need to compare the patient's DNA against a standard model human genome. Until now, medical practitioners in Japan had been using the international standard genome model completed by the Human Genome Project in 2003.

However, this model was based primarily on people of European and African descent and did not reflect genetic variations specific to Japanese people, sometimes resulting in analysis errors.

The JG1 reference model was built from the genomes of three volunteers, who were participating in follow-up health studies conducted by the university's Tohoku Medical Megabank Organization on residents of northeastern Japan and elsewhere after the March 2011 Great East Japan Earthquake. The Tohoku University team began assembling and releasing the JG1 model bit by bit starting in 2016. All the parts were stitched together for the first time in the reference model released on Feb. 25.

According to the research team, they found some 246,000 differences between the DNA base sequences of the international model and the Japan-specific genome, 98 percent of which have been reflected in the JG1 reference model.

"We paid attention to getting regional balance and avoiding a biased model by making sure the three volunteers (providing their genetic data) were not just from northeastern Japan," said Tohoku Medical Megabank Organization chief and Tohoku University professor Masayuki Yamamoto. "In terms of clinical applications, it (the JG1 model) will lead to higher successful diagnosis rates for childhood rare diseases and other conditions," he added.

(Japanese original by Norikazu Chiba, Science & Environment News Department)

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