Recently I had my DNA genotyped by 23andMe. After working at Sanger for two years, I had been looking forward to finding out what my own genome had to say about myself, particularly regarding my ancestry. I am from Beijing and both of my parents are ethnically Han Chinese – the largest ethnic group which accounts for 92% population in China. Having witnessed my colleagues’ surprise at finding French, Ashkenazi and Scandinavian ancestry in their own DNA data, I could not help but get my hopes up to discover some surprising elements in my own ATGCs.

23andmeHowever, 23andMe left me feeling a little underwhelmed. Its ancestry analysis told me I’m 99.4% East Asian and Native American, a little like finding out that beef is 99.4% cow (something you can not always take from granted in the UK). Compared with the detailed breakdown you receive if you are European, such a vague composition is rather disappointing. Luckily, with a bit of experience in analysing genotype data, I could try other means. I combined my genotype with the east Asian cohort from our Inflammatory Bowel Disease (IBD) studies, and did a standard Principal Component Analysis (PCA) using WDIST, an experimental rewrite of the PLINK command-line tool which benefits from a vastly improved speed-up of the Identity-by-descent (—genome) calculation.

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