Our group is working on two main subjects: genomic sequencing in human and model organisms and clone and transcript mapping for providing sequence-ready maps as well as for disease gene identification. The team started with the chromosome-wide mapping efforts of human chromosome X but shifted their attention also to other regions of the human genome. Next to chromosome X one major region of interest is chromosome 3q21. We contributed sequence-ready maps required for the genomic sequencing of human chromosome X and 3. We established a gene catalogue of the human X chromosome based on sequencing comparison between genomic sequence and UniGene cDNA sequences. Based on this catalogue we generated the first chromosome-specific cDNA microarray. The Integrated X Chromosome Database (IXDB) was established in 1996 and is maintained since than. IXDB serves as a repository for data connected to the X chromosome. Since 2000 the team is also involved in the genomic sequencing of selected parts of human chromosomes 1, 3, 17, and X (more). In addition, we are involved in sequencing projects of parts of chromosome 2 and 6 of mouse, the MHC of the rat (RT1), and parts of the rhesus MHC. Recently, we contributed to the finished sequence of chimpanzee chromosome 22 the equivalent of human chromosome 21, a project coordinated in Germany by M.-L. Yaspo. One major topic of our group is the experimental verification of differences within the coding regions between chimpanzee and human. Projects to contribute to the sequencing of chimpanzee chromosomes X and Y are initiated, which special emphasis to Xq28 and regions associated with mental retardation. In addition to mapping and sequencing, we are involved in several disease gene identification projects. We contributed towards the successful cloning of BSND (Bartter syndrome with sensorineural deafness and kidney failure, chromosome 1), NPHP4 (nephronophthisis and retinitis pigmentosa, chromosome 1), ATPC1 (Hailey-Hailey disease, chromosome 3), NPHP3 (adolescent nephronophthisis type 3, chromosome 3), DNAH5 (primary cilary dyskinesia, chromosome 5), and TM4SF2 (X-linked mental retardation, chromosome X).