Friday, July 01, 2005

Copy number polymorphisms in the human genome

total sequences in human genome database
Total number of sequences deposited in the HTGS domain of GenBank as of 2000. Up-to-date numbers are here

I may need to start a separate blog just to keep track of genomic studies. The synergy between reduced sequencing costs and strategies and increased computational power has meant a surge of information about the human genome. More is known about the human genome than any other animal's, and possibly more than any other eukaryote. This has allowed people to ask very basic questions about the DNA content of such an organism, such as the level of diversity which exists among individuals of a species. I think lots more suprises are in store in just the next few years.

A review in the subscription journal Trends in Genetics talks about yet another category of variation: small changes (as small as 200 bases insertions and deletions) in the DNA sequences of normal humans known as copy-number polymorphisms (CNPs). Up to 200 such human CNPs have been identified in just two recent studies. The field is in its infancy, so there are no estimates how many would be expected in the genomes of humans. But analysis of this category of variation will complement the more famous single-nucleotide polymorphisms (SNPs) in population studies.

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