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Find out what a ‘healthy genome’ looks like and investigate how normal genetic variation and different sequencing technologies will influence the clinical diagnosis of harmful genetic variants. 

A total of six different DNA sequencing technologies were used (the original Sanger approach, plus current WGS methods from Roche, ABI, Illumina, Helicos and Complete Genomics) to sequence the genomes of ten people (three African, two Asian and five Caucasian) including men and women. 34 million DNA sequence variants (SNPs) were analysed, and disease-related variants identified from the OMIM database. 

The type of sequencing technology affected findings. Ethnicity had a significant influence on genetic variation, irrespective of the technology used, with the African genomes having nearly twice as many disease variants as the Eurasian ones. On average, each genome contained around 100 disease-related variants, none of them severe. 

It will be essential to take variability between sequencing technologies and ethnicity into account in using genomic analysis for clinical diagnosis and prognosis. Much more research is needed to characterise multiple genomes, examine key ethnic differences and establish what constitute baseline references for identifying rare variants of possible clinical significance. 

This study, whilst limited to only ten genomes, gives some insight into the complexity of human genome sequence variation and the scale of the task ahead in researching it properly, as well as developing whole genome sequencing as a clinical tool for general use.