To continue providing efficient and timely processing, annotation, and dissemination of data, dbSNP’s architecture and process flow have been redesigned. The technical redesign prepares the database for increasing data volumes and providing timely, effective and trustworthy reference SNP results as submission rates continue to increase.
Highlights of the new system include:
- Use of data objects instead of a relational database
- Improved algorithms for clustering data into unique Reference SNPs
- Automation of the entire process to provide timely releases
- Guaranteed data consistency across dbSNP data accessed using web-based products or downloaded content, such as VCF and FTP files
NCBI is pleased to announce the initial data release of RefSeq Functional Elements, a resource that provides RefSeq and Gene records for experimentally validated human and mouse non-genic functional elements. Data can be accessed via Gene, Nucleotide, BLAST, BioProject, Graphical Displays and FTP.
In an earlier blog post, we discussed how sequence updates in GRCh38, the most recent version of the human reference genome, filled in a gap in human chromosome 17 near position 21,300K and expanded the region by 500K (500,000 base pairs). In this post, we will again consider this same region, but with an emphasis now on how GRCh38 also improved the gene annotation.
Figure 1. Annotation of a region of chromosome 17 near the KCNJ12 and KCNJ18 genes. Top panel: Annotation release 105 on GRCh37.p13 represented by a configured graphic display of sequence record NC_000017.10. Bottom panel: Annotation release 106 on assembly GRCh38 represented by a configured graphic display of sequence record NC_000017.11. New gene models are circled.
In a previous blog post, we explained several important concepts about the human reference genome. We presented a region of human chromosome 17 as an example of a location where the genome sequence was not fully assembled. In this post, we are going to revisit the same gapped region to see how the Genome Reference Consortium (GRC) changed this part of the genome in GRCh38, the updated human reference assembly released in December 2013. This region represents just one of the more than 1,000 changes and improvements that the GRC introduced in GRCh38.
This month marks a major event in the realm of human genome research: the release of a new assembly of the genome, GRCh38. It has been over four years since the last major release (GRCh37 in March 2009), and we are going to explore several aspects of this new assembly in a series of blog posts over the coming weeks. In this initial post, we will give an overview of the data flow so that you will understand how NCBI received the data, where the data are at NCBI and what genome annotations you can expect from NCBI in the near future.
What is a genome assembly?
The haploid human genome consists of 22 autosomal chromosomes and the Y and the X chromosomes. Each of the chromosomes represents a single DNA molecule, a sequence of millions of nucleotide bases. These molecules are linear, so one might expect that we should represent each chromosome by a single, continuous sequence.
Unfortunately, this is not the case for two main reasons: 1) because of the nature of genomic DNA and the limitations of our sequencing methods, some parts of the genome remain unsequenced, and 2) emerging evidence suggests that some regions of the genome vary so much between individual people that they cannot be represented as a single sequence.
In response to this, modern genomic data sets present a model of the genome known as a genome assembly. This post will introduce the basic concepts of how we produce such assemblies as well as some basic vocabulary.