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Chromosome 9 is highly structurally polymorphic. It contains the largest autosomal block of heterochromatin, which is heteromorphic in 6-8% of humans, whereas pericentric inversions occur in more than 1% of the population. The finished euchromatic sequence of chromosome 9 comprises 109,044,351 base pairs and represents >99.6% of the region. Analysis of the sequence reveals many intra- and interchromosomal duplications, including segmental duplications adjacent to both the centromere and the large heterochromatic block. We have annotated 1,149 genes, including genes implicated in male-to-female sex reversal, cancer and neurodegenerative disease, and 426 pseudogenes. The chromosome contains the largest interferon gene cluster in the human genome. There is also a region of exceptionally high gene and G + C content including genes paralogous to those in the major histocompatibility complex. We have also detected recently duplicated genes that exhibit different rates of sequence divergence, presumably reflecting natural selection. [ABSTRACT FROM AUTHOR]

Reports the construction of maps for chromosomes 1, 6, 9, 10, 13, 20, and X, by building landmark maps, isolating bacterial clones and assembling contigs. Ability to establish the long-range organization of the maps early in the project using this approach; Simplification of contig extension, gap closure, and problem-solving with this method because of containment within local regions; Percentage of the euchromatic regions and chromosome-specific markers in the human gene map which these represent; Applications for assessing sequenced clones.