Not Quite A Thousand Genomes

by jeeg 8. November 2010 22:23

It took about 10 years and almost $3 billion to sequence the first human genome. With current technology, it takes about 4-6 weeks and costs on the order of only $10,000 to $20,000 (or about $1 per gene for all 20,000 genes that make up our genomes). This dramatic reduction in costs is ongoing and predicted to make possible a $1,000 genome within two years. This price point, which is no more than the cost of many imaging studies and other medical procedures that are done routinely and repeatedly in current medical practice, is leading to a revolution in molecular diagnostics that a new generation of pathologists is already being trained to apply.

In the meantime, understanding our genomes from a basic biology and evolutionary point of view is the focus of much research activity. After all, we could only learn so much from an n=1 sample of the first human genome. Therefore, once it became economically feasible, groups began gathering and cataloging genome data on a “population” scale to gain a much broader and deeper knowledge of human genetic variation and the relationship between
genotypes and phenotypes. The so-called “thousand genome” project is aimed at increasing our understanding of human genomes from a basic biology and evolutionary point of view.

article in Nature  reported on the findings from genome sequence analysis of 179 anonymous donors and also two family "trios" (mother-father-child). The project team also sequenced collections of genes from 697 individuals from seven genetically diverse populations. The results showed that each of us carries about 250-300 "loss of function" mutations in our genes but that, in most cases, these mutant genes are clinically silent because the mutations occur in only one of the two alleles that we inherited from our parents.

Why do we have these mutations at all? Because while the replication of DNA is a highly accurate process, it is not perfect and even an extremely low replication error rate can lead to millions of mutations accruing over time in our genomes which are three billion base pairs in size.

By: Michele R. Berman, MD , MEDPAGE 


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