The April 2003 human reference sequence is based on NCBI Build 33. It has been released in conjunction with the International Human Genome Sequencing Consortium's announcement of the successful completion of the Human Genome Project.

### Sample position queries

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.

Request: | Genome Browser Response:
chr7 |  | Displays all of chromosome 7
20p13 |  | Displays region for band p13 on chr 20
chr3:1-1000000 |  | Displays first million bases of chr 3, counting from p arm telomere
scf1:1-1000000 |  | Displays first million bases of scaffold 1 of an unmapped genome assembly
D16S3046 |  | Displays region around STS marker D16S3046 from the Genethon/Marshfield maps. Includes 100,000 bases on each side as well.
RH18061;RH80175 |  | Displays region between STS markers RH18061;RH80175. This syntax may also be used for other range queries, such as between cytobands and uniquely-determined ESTs, mRNAs, refSeqs, etc.
AA205474 |  | Displays region of EST with GenBank accession AA205474 in BRCA1 cancer gene on chr 17
AC008101 |  | Displays region of clone with GenBank accession AC008101
AF083811 |  | Displays region of mRNA with GenBank accession number AF083811
PRNP |  | Displays region of genome with HUGO Gene Nomenclature Committee identifier PRNP
NM_017414 |  | Displays the region of genome with RefSeq identifier NM_017414
NP_059110 |  | Displays the region of genome with protein accession number NP_059110
11274 |  | Displays the region of genome with Entrez Gene identifier 11274
pseudogene mRNA |  | Lists transcribed pseudogenes, but not cDNAs
homeobox caudal |  | Lists mRNAs for caudal homeobox genes
zinc finger |  | Lists many zinc finger mRNAs
kruppel zinc finger |  | Lists only kruppel-like zinc fingers
huntington |  | Lists candidate genes associated with Huntington's disease
zahler |  | Lists mRNAs deposited by scientist named Zahler
Evans,J.E. |  | Lists mRNAs deposited by co-author J.E. Evans
Use this last format for author queries. Although GenBank requires the search format Evans JE, internally it uses the format Evans,J.E..

### Assembly details

This reference sequence covers about 99 percent of the human genome's gene-containing regions, and has been sequenced to an accuracy of 99.99 percent. The missing portions are essentially contained in less than 400 defined gaps that represent DNA regions with unusual structures that can't be reliably sequenced using current technology. The average DNA letter now lies within a stretch of approximately 27,332,000 base pairs of uninterrupted sequence!

Chromosomal sequences for this release were assembled by the International Human Genome Sequencing Consortium sequencing centers and verified by NCBI and UCSC. In some cases, sequence joins between adjacent clones 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 hg15 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.

### Statistical information

- Non-Standard Join Certificates
- Summary Statistics
- Chromosome Reports
- Genome Map Plots