From: Human genetics and genomics a decade after the release of the draft sequence of the human genome
Chromosome | Chromosome length (bp)a | Number of known protein-coding genes per chromosomea | Gene density (genes/Mb) | Special features | Reference |
---|---|---|---|---|---|
1 | 247,249,719 | 2,189 | 8.85 | Largest human chromosome. Rich in disease genes. Huge (~30 Mb) pericentromeric heterochromatic region at 1q12 spans ~5% of the length of the chromosome. Contains clusters of amylase genes (1p21), U1 snRNA genes (1q12-q22) and 5S RNA genes (1q) as well as multiple (~250) tRNA genes | 1 |
2 | 242,951,149 | 1,328 | 5.47 | Chromosome 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 chromosome | 2 |
3 | 199,501,827 | 1,112 | 5.57 | Lowest rate of segmental duplication of all human chromosomes. Contains several olfactory receptor gene clusters | 3 |
4 | 191,273,063 | 797 | 4.17 | Chromosome 4 (along with chromosome 2) exhibits the lowest recombination rate of all the autosomes. Highest percentage of LINE elements among all chromosomes | 2 |
5 | 180,857,866 | 903 | 4.99 | Rich in intra-chromosomal duplications. Contains interleukin and protocadherin gene clusters on 5q31 | 4 |
6 | 170,899,992 | 1,133 | 6.62 | Harbours the major histocompatibility complex and the largest tRNA gene cluster in the human genome. Contains at least three imprinted genes | 5 |
7 | 158,821,424 | 1,023 | 6.44 | Contains the highest number of intra-chromosomal duplications among all human chromosomes. Contains at least six imprinted genes | 6, 7 |
8 | 146,274,826 | 747 | 5.11 | Contains 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 selection | 8 |
9 | 140,273,252 | 929 | 6.62 | Structurally highly polymorphic. Contains the large (~14 Mb) block of pericentromeric heterochromatin. Contains large numbers of intra- and inter-chromosomal segmental duplications, as well as the largest interferon gene cluster in the human genome (9p22) | 9 |
10 | 135,374,737 | 834 | 6.16 | Region of extensive segmental duplication located on 10q11 | 10 |
11 | 134,452,384 | 1,385 | 10.30 | Rich in both genes and disease genes. Contains 40% of all olfactory receptor gene clusters. Contains at least nine imprinted genes | 11 |
12 | 132,349,534 | 1,080 | 8.16 | Chromosome 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 12q13 | 12 |
13 | 114,142,980 | 361 | 3.16 | Low 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 one imprinted gene | 13 |
14 | 106,368,585 | 669 | 6.29 | This 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 genes | 14 |
15 | 100,338,915 | 641 | 6.39 | This 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 genes | 15 |
16 | 88,827,254 | 925 | 10.41 | Relatively high gene density. Contains a large number of segmental duplications | 16 |
17 | 78,774,742 | 1,236 | 15.69 | High gene density. Has undergone extensive intra-chromosomal rearrangement, many of which were probably mediated by segmental duplications. High G + C content of 45% (genome average: 41%) | 17 |
18 | 76,117,153 | 295 | 3.88 | Low gene density overall. Contains serpin gene cluster at 18q21.3 | 18 |
19 | 63,811,651 | 1,443 | 22.61 | Highest 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 two imprinted genes | 19 |
20 | 62,435,964 | 617 | 9.88 | Smallest metacentric autosome. Rich in both genes and disease genes. Contains type 2 cystatin gene cluster and at least two imprinted genes | 20 |
21 | 46,944,323 | 284 | 6.05 | Smallest human chromosome with fewer genes than any other autosome. This acrocentric chromosome contains ribosomal RNA genes at 21p12 | 21 |
22 | 49,691,432 | 519 | 10.44 | This acrocentric chromosome contains ribosomal RNA genes at 22p12. Relatively high gene density. Clusters of segmental duplications at 22q11.2 are associated with several genomic disorders | 22 |
X | 154,913,754 | 891 | 5.75 | Contains 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 chromosome, 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%) | 23 |
Y | 57,772,954 | 80 | 1.38 | Lowest 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 chromosomes has led to a gradual degeneration of Y chromosomal genes over evolutionary time. However, the absence of recombination, at least within the extensive non-recombining region of the Y chromosome, has also favoured the evolutionary accumulation of transposable elements on the Y chromosome | 24 |