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Sequencing the Human Genome: Novel Insights into its Structure and Function

  1. Hildegard Kehrer-Sawatzki1,
  2. David N Cooper2

Published Online: 15 JUL 2008

DOI: 10.1002/9780470015902.a0001899.pub2

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Kehrer-Sawatzki, H. and Cooper, D. N. 2008. Sequencing the Human Genome: Novel Insights into its Structure and Function. eLS. .

Author Information

  1. 1

    University of Ulm, Institute of Human Genetics, Ulm, Germany

  2. 2

    Cardiff University, Institute of Medical Genetics, Cardiff, UK

Publication History

  1. Published Online: 15 JUL 2008

This is not the most recent version of the article. View current version (15 NOV 2016)

Table 1. Special features of human chromosomes 1–22 including respective lengths, gene number and density
ChromosomeChromosome length (bp)aNumber of known protein-coding genes per chromosomeaGene density (genes/Mb)Special features of the chromosomeReference
  1. Notes: LINE, long interspersed nuclear element.

  2. a

    Chromosome lengths and the numbers of genes per chromosome are according to the Ensembl database, version 47.36. The chromosome length corresponds to the length of each chromosome that has been sequenced so far. The number of known protein-coding genes represents a conservative estimate of the likely total number, comprising genes which have been fully annotated.

1247 249 71921898.85Largest human chromosome. Rich in disease genes. Huge (∼30 Mb) pericentromeric heterochromatic region at 1q12 spans approximately 5% of the length of the chromosome. Contains clusters of amylase genes (1p21), U1 snRNA genes (1q12–q22) and %S RNA genes (1q) as well as multiple (∼250) tRNA genesGregory et al. 2006
2242 951 14913285.47Chromosome 2 (along with chromosome 4) exhibits the lowest recombination rate of all the autosomes. Contains at 2q13 an ancient telomere–telomere fusion junction at the position where two ape chromosomes once fused to give rise to this human chromosomeHillier et al. 2005
3199 501 82711125.57Lowest rate of segmental duplication of all human chromosomes. Contains several olfactory receptor gene clustersMuzny et al. 2006
4191 273 0637974.17Chromosome 4 (along with chromosome 2) exhibits the lowest recombination rate of all the autosomes. Highest percentage of LINE among all chromosomesHillier et al. 2005
5180 857 8669034.99Rich in intrachromosomal duplications. Contains interleukin and protocadherin gene clusters on 5q31Schmutz et al. 2004b
6170 899 99211336.62Harbours the major histocompatibility complex and the largest tRNA gene cluster in the human genome. Contains at least 3 imprinted genesMungall et al. 2003
7158 821 42410236.44Contains the highest number of intrachromosomal duplications among all human chromosomes. Contains at least 6 imprinted genesHillier et al. 2003 and Scherer et al. 2003
8146 274 8267475.11Contains a fast evolving 15 Mb region on distal 8p with genes related to the innate immunity and nervous systems that appear to have evolved under positive selectionNusbaum et al. 2006
9140 273 2529296.62Structurally highly polymorphic. Contains the large (∼14 Mb) block of pericentromeric heterochromatin. Contains large numbers of intra- and interchromosomal segmental duplications as well as the largest interferon gene cluster in the human genome (9p22)Humphray et al. 2004
10135 374 7378346.16Region of extensive segmental duplication located on 10q11Deloukas et al. 2004
11134 452 384138510.30Rich in both genes and disease genes. Contains 40% of all olfactory receptor gene clusters. Contains at least 9 imprinted genesTaylor et al. 2006
12132 349 53410808.16Chromosome 12 has a unique history of evolutionary rearrangements that occurred in the rodent and primate lineages. Contains clusters of proline-rich protein and type II keratin genes at 12q13Scherer et al. 2006
13114 142 9803613.16Low gene density in general; contains a central 38 Mb segment where the gene density drops to only 3.1 genes per Mb. This acrocentric chromosome contains ribosomal RNA genes at 13p12 and at least 1 imprinted geneDunham et al. 2004
14106 368 5856696.29This acrocentric chromosome contains ribosomal RNA genes at 14p12. Contains two 1 Mb regions of crucial importance to the immune system (T-cell receptor and immunoglobulin heavy-chain genes). Contains serpin gene cluster at 14q32.1 and several regions with imprinted genesHeilig et al. 2003
15100 338 9156416.39This acrocentric chromosome contains ribosomal RNA genes at 15p12. Two large clusters of clinically important segmental duplications are located in the proximal and distal regions of 15q. Contains a number of imprinted genesZody et al. 2006a
1688 827 25492510.41Relatively high gene density. Contains a large number of segmental duplicationsMartin et al. 2004
1778 774 742123615.69High gene density. Has undergone extensive intrachromosomal rearrangement, many of which were probably mediated by segmental duplications. High G+C content of 45% (genome average: 41%)Zody et al. 2006b
1876 117 1532953.88Low gene density overall. Contains serpin gene cluster at 18q21.3Nusbaum et al. 2005
1963 811 651144322.61Highest gene density of all human chromosomes. One quarter of the genes on chromosome 19 belong to tandemly arranged gene families, encompassing 25% of the length of the chromosome. High G+C content of 48–49% (genome average: 41%). Repetitive sequences constitute 53–57% of the chromosome as compared with a genome average of 40–44%. Contains clusters of olfactory receptor genes and cytochrome P450 genes and multiple clusters of zinc-finger genes, and at least 2 imprinted genesGrimwood et al. 2004
2062 435 9646179.88Smallest metacentric autosome. Rich in both genes and disease genes. Contains type 2 cystatin gene cluster and at least two imprinted genesDeloukas et al. 2001
2146 944 3232846.05Smallest human chromosome with fewer genes than any other autosome. This acrocentric chromosome contains ribosomal RNA genes at 21p12Hattori et al. 2000
2249 691 43251910.44This acrocentric chromosome contains ribosomal RNA genes at 22p12. Relatively high gene density. Clusters of segmental duplications at 22q11.2 are associated with several genomic disordersDunham et al. 1999
X154 913 7548915.75Contains the pseudoautosomal regions, PAR1 and PAR2, at the tips of the short and long arms, respectively. These regions are essential for normal male meiosis and recombination. PAR1 undergoes an obligate crossover with the Y, thereby giving this region the highest recombination rate in the human genome, at least in males. One X-chromosome is subject to inactivation in females. Highly enriched in interspersed repeats and has a low G+C content of 39% (genome average: 41%)Ross et al. 2005
Y57 772 954801.38Lowest gene density of all human chromosomes (contains only 82 known genes). Contains the male-specific region which is a mosaic of heterochromatin and euchromatic X-transposed, X-degenerate and ampliconic sequences, that make-up 30% of the euchromatin. PAR1 undergoes an obligate crossover with the X-chromosome. The virtual absence of homologous recombination between the X- and the Y-chromosome has led to a gradual degeneration of Y chromosomal genes over evolutionary time. However, the absence of recombination, at least within the extensive nonrecombining region of the Y, has also favoured the evolutionary accumulation of transposable elements on the Y chromosomeSkaletsky et al. 2003