Saturday, July 31, 2010

Who is Patient N?

The DNA donor was selected from a large pool of more than 1,300 volunteers who are participating in an unpublished genotyping survey of Russia’s ethnic populations. The goal of that study is eventually to analyze 4,000 people from about 40 nationalities living around Russia and surrounding territories, from Uzbekistan in central Asia to the Arctic Ocean in the north, and from the Pacific to Poland in the west (essentially spanning the former Soviet Union).
“Using Principal Component Analysis (PCA), we could put different individuals into various ethnic groups governing this geographical distribution,” says Prokhortchouk. “You can distinguish Russians as an ethnic group from Tatars or Poles, Siberia, and so on.”
Based on the PCA, Patient N was selected as an archetypal Russian genome. “Mathematically speaking, he’s Russian!” says Prokhortchouk. “I don’t know anything about his parents or what language he speaks or where he lives, but I know that under mathematical rules [PCA], he’s Russian!”
He is also a renal cancer patient, which provides a further rationale for studying this genome. That work is ongoing. The Prokhortchouk and Skryabin labs are part of the International Cancer Genome Consortium (see Nature, April 2010). Preliminary analysis of the renal cancer focused on SNPs that have been associated in genome wide association studies [GWAS] in renal cancer. “Using linkage disequilibrium, you can trace the SNPs [in the Patient N genome] close to the marker SNPs and go to particular exons in particular genes.” One of those looks particularly interesting, he said, but declined to elaborate.
Although the decision to publish in an unknown Russian journal, which is not yet recognized in PubMed, stifled media attention abroad, the paper attracted considerable media attention inside Russia when it was published last year. The big question on reporters’ minds was: Who is Patient N? “They thought it was Prime Minister Putin. It’s not true!” said Prokhortchouk. Speculation was not unreasonable, given that according to Wikipedia, the institute director Kovalchuk’s brother is described as the “personal banker” to Putin.
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