The July 2003 human reference sequence (UCSC version hg16) is based on NCBI Build 34 and was produced by the International Human Genome Sequencing Consortium. The sequence covers about 99 percent of the gene-containing regions in the genome, and has been sequenced to an accuracy of 99.99 percent. Of note in this release is the addition of the pseudoautosomal regions of the Y chromosome. This sequence was taken from the corresponding regions in the X chromosome and is an exact duplication of that sequence.
There are 2,843,433,602 finished sequenced bases in the ordered and oriented portion of the assembly, which is an increase of 0.4 percent, or approximately 11 Mb, over the Build 33 assembly. The reference sequence is considered to be "finished", a technical term indicating that the sequence is highly accurate (with fewer than one error per 10,000 bases) and highly contiguous (with the only remaining gaps corresponding to regions whose sequence cannot be reliably resolved with current technology). Future work on the reference sequence will focus on improving accuracy and reducing gaps in the sequence.
Some sequence joins between adjacent clones in this assembly could not be computationally validated because the clones originated from different haplotypes and contained polymorphisms in the overlapping sequence, or the overlap was too small to be to be reliable. In these instances, the sequencing center responsible for the particular chromosome has provided data to support the join in the form of an electronic certificate. These certificates may be reviewed through the link below.
Bulk downloads of the sequence and annotation data are available via the Genome Browser FTP server or the Downloads page. The hg16 annotation tracks were generated by UCSC and collaborators worldwide. See the Credits page for a detailed list of the organizations and individuals who contributed to the success of this release.
A genome position can be specified by the accession number of a sequenced genomic clone, an mRNA or EST or STS marker, or a cytological band, a chromosomal coordinate range, or keywords from the GenBank description of an mRNA. The following list shows examples of valid position queries for the human genome. See the User's Guide for more information.