IXDB, an X chromosome integrated database (update)

Chromosome specific databases are an important research tool as they integr ate data from different directions, such as genetic and physical mapping da ta, expression data, sequences etc. They supplement the genome-wide reposit ories in molecular biology, such as GenBank, Swiss-Prot or OMIM, which usua lly concentrate on one type of information. The Integrated X Chromosome Dat abase (IXDB, http://ixdb.mpimgberlin-dahtem.mpg.de/) is a repository for ph ysical mapping data of the human X chromosome and aims at providing a globa l view of genomic data at a chromosomal level. We present here an update of IXDB which includes schema extensions for storing submaps and sequence inf ormation, additional links to external databases, and the integration of an increasing number of physical and transcript mapping data. The gene data w as completely updated according to the approved gene symbols of the HUGO No menclature Committee. IXDB receives over 1000 queries per month, an indicat ion that its content is valuable to researchers seeking mapping data of the human X chromosome.