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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®

Chromosome 2

Reviewed April 2009

What is chromosome 2?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 2, one copy inherited from each parent, form one of the pairs. Chromosome 2 is the second largest human chromosome, spanning about 243 million building blocks of DNA (base pairs) and representing almost 8 percent of the total DNA in cells.

Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 2 likely contains 1,300 to 1,400 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.

Genes on chromosome 2 are among the estimated 20,000 to 25,000 total genes in the human genome.

Genetics Home Reference provides information about the following genes on chromosome 2:

  • ABCA12
  • ABCB11
  • ABCG5
  • ABCG8
  • ACVR1
  • AGPS
  • AGXT
  • ALK
  • ALMS1
  • ALS2
  • APOB
  • ATG16L1
  • ATP6V1B1
  • BCS1L
  • BIN1
  • BMPR2
  • BOLA3
  • CACNB4
  • CHN1
  • CNGA3
  • COL3A1
  • COL4A3
  • COL4A4
  • COL5A2
  • COL6A3
  • CPS1
  • CXCR4
  • CYP1B1
  • CYP27A1
  • D2HGDH
  • DCTN1
  • DES
  • DFNB59
  • DNMT3A
  • DYSF
  • EDAR
  • EIF2B4
  • EPAS1
  • ERCC3
  • FN1
  • GALNT3
  • IDH1
  • IL1A
  • ITGA6
  • LCT
  • LRP2
  • MATN3
  • MCEE
  • MCM6
  • MLPH
  • MPV17
  • MSH2
  • MSH6
  • MSTN
  • MYCN
  • NEB
  • NFU1
  • NPHP1
  • ORC4
  • OTOF
  • PAX3
  • PAX8
  • PNKD
  • POMC
  • PROC
  • REEP1
  • RPS7
  • SCN1A
  • SCN9A
  • SIX3
  • SLC3A1
  • SLC19A3
  • SLC40A1
  • SOS1
  • SP110
  • SPR
  • SRD5A2
  • ST3GAL5
  • STAT4
  • SUCLG1
  • TMEM127
  • TPO
  • TTN
  • UGT1A1
  • WDR35
  • ZAP70
  • ZEB2

How are changes in chromosome 2 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 2. This list of disorders associated with genes on chromosome 2 provides links to additional information.

Genetics Home Reference provides information about the following conditions related to genes on chromosome 2:

  • 2-hydroxyglutaric aciduria
  • 5-alpha reductase deficiency
  • achromatopsia
  • African iron overload
  • Alport syndrome
  • Alström syndrome
  • amyotrophic lateral sclerosis
  • ankylosing spondylitis
  • asphyxiating thoracic dystrophy
  • benign recurrent intrahepatic cholestasis
  • biotin-thiamine-responsive basal ganglia disease
  • Björnstad syndrome
  • carbamoyl phosphate synthetase I deficiency
  • centronuclear myopathy
  • cerebrotendinous xanthomatosis
  • collagen VI-related myopathy
  • congenital hypothyroidism
  • congenital insensitivity to pain
  • cranioectodermal dysplasia
  • craniofacial-deafness-hand syndrome
  • Crigler-Najjar syndrome
  • Crohn disease
  • cystinuria
  • cytogenetically normal acute myeloid leukemia
  • deoxyguanosine kinase deficiency
  • Diamond-Blackfan anemia
  • distal hereditary motor neuropathy, type V
  • Donnai-Barrow syndrome
  • dopa-responsive dystonia
  • early-onset glaucoma
  • Ehlers-Danlos syndrome
  • epidermolysis bullosa with pyloric atresia
  • episodic ataxia
  • erythromelalgia
  • familial dilated cardiomyopathy
  • familial erythrocytosis
  • familial hemiplegic migraine
  • familial hypertrophic cardiomyopathy
  • familial hypobetalipoproteinemia
  • familial male-limited precocious puberty
  • familial paroxysmal nonkinesigenic dyskinesia
  • Feingold syndrome
  • fibrodysplasia ossificans progressiva
  • fibronectin glomerulopathy
  • Gilbert syndrome
  • GM3 synthase deficiency
  • GRACILE syndrome
  • Griscelli syndrome
  • harlequin ichthyosis
  • hepatic veno-occlusive disease with immunodeficiency
  • hereditary hemochromatosis
  • hereditary myopathy with early respiratory failure
  • homocystinuria
  • hypercholesterolemia
  • hyperphosphatemic familial tumoral calcinosis
  • hypohidrotic ectodermal dysplasia
  • idiopathic inflammatory myopathy
  • infantile-onset ascending hereditary spastic paralysis
  • intrahepatic cholestasis of pregnancy
  • isolated Duane retraction syndrome
  • Joubert syndrome
  • juvenile idiopathic arthritis
  • juvenile myoclonic epilepsy
  • juvenile primary lateral sclerosis
  • lactose intolerance
  • lamellar ichthyosis
  • leukoencephalopathy with vanishing white matter
  • Leydig cell hypoplasia
  • limb-girdle muscular dystrophy
  • long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency
  • lung cancer
  • Lynch syndrome
  • malignant migrating partial seizures of infancy
  • Meier-Gorlin syndrome
  • methylmalonic acidemia
  • microcephaly-capillary malformation syndrome
  • mitochondrial complex III deficiency
  • mitochondrial trifunctional protein deficiency
  • Miyoshi myopathy
  • Mowat-Wilson syndrome
  • MPV17-related hepatocerebral mitochondrial DNA depletion syndrome
  • multiple epiphyseal dysplasia
  • multiple mitochondrial dysfunctions syndrome
  • multiple pterygium syndrome
  • myofibrillar myopathy
  • myostatin-related muscle hypertrophy
  • nemaline myopathy
  • nephronophthisis
  • neuroblastoma
  • nonsyndromic deafness
  • nonsyndromic holoprosencephaly
  • nonsyndromic paraganglioma
  • Noonan syndrome
  • ovarian cancer
  • paroxysmal extreme pain disorder
  • Perry syndrome
  • Peters anomaly
  • primary hyperoxaluria
  • primary myelofibrosis
  • progressive familial intrahepatic cholestasis
  • proopiomelanocortin deficiency
  • prostate cancer
  • protein C deficiency
  • pulmonary arterial hypertension
  • pulmonary veno-occlusive disease
  • renal tubular acidosis with deafness
  • rheumatoid arthritis
  • rhizomelic chondrodysplasia punctata
  • Salih myopathy
  • Schimke immuno-osseous dysplasia
  • Senior-Løken syndrome
  • sepiapterin reductase deficiency
  • sitosterolemia
  • small fiber neuropathy
  • spastic paraplegia type 4
  • spastic paraplegia type 31
  • succinate-CoA ligase deficiency
  • surfactant dysfunction
  • systemic lupus erythematosus
  • systemic scleroderma
  • tibial muscular dystrophy
  • trichothiodystrophy
  • Waardenburg syndrome
  • Waldenström macroglobulinemia
  • warfarin resistance
  • xeroderma pigmentosum
  • ZAP70-related severe combined immunodeficiency

Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 2.

2q37 deletion syndrome

2q37 deletion syndrome is caused by a deletion of genetic material from a specific region in the long (q) arm of chromosome 2. The deletion occurs near the end of the chromosome at a location designated 2q37. The size of the deletion varies among affected individuals. The signs and symptoms of this disorder, which may include intellectual disability, autism, short stature, obesity, and characteristic facial features, are probably related to the loss of multiple genes in this region.


Changes in chromosome 2 have been identified in several types of cancer. These genetic changes are somatic, which means they are acquired during a person's lifetime and are present only in certain cells. For example, a rearrangement (translocation) of genetic material between chromosomes 2 and 3 has been associated with cancers of a certain type of blood cell originating in the bone marrow (myeloid malignancies).

Trisomy 2, in which cells have three copies of chromosome 2 instead of the usual two copies, has been found in myelodysplastic syndrome. This disease affects the blood and bone marrow. People with myelodysplastic syndrome have a low number of red blood cells (anemia) and an increased risk of developing a form of blood cancer known as acute myeloid leukemia.

other chromosomal conditions

Another chromosome 2 abnormality is known as a ring chromosome 2. A ring chromosome is formed when breaks occur at both ends of the chromosome and the broken ends join together to form a circular structure. Individuals with this chromosome abnormality often have developmental delay, small head size (microcephaly), slow growth before and after birth, heart defects, and distinctive facial features. The severity of symptoms typically depends on how many and which types of cells contain the ring chromosome 2.

Other changes involving the number or structure of chromosome 2 include an extra piece of the chromosome in each cell (partial trisomy 2) or a missing segment of the chromosome in each cell (partial monosomy 2). These changes can have a variety of effects on health and development, including intellectual disability, slow growth, characteristic facial features, weak muscle tone (hypotonia), and abnormalities of the fingers and toes.

Is there a standard way to diagram chromosome 2?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.

Ideogram of chromosome 2
See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about chromosome 2?

You may find the following resources about chromosome 2 helpful. These materials are written for the general public.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What glossary definitions help with understanding chromosome 2?

acute ; acute myeloid leukemia ; anemia ; autism ; bone marrow ; cancer ; cell ; chromosome ; deletion ; developmental delay ; disability ; DNA ; hypotonia ; inherited ; leukemia ; microcephaly ; monosomy ; muscle tone ; myelodysplastic syndrome ; myeloid ; rearrangement ; short stature ; stature ; syndrome ; translocation ; trisomy

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Aldred MA, Sanford RO, Thomas NS, Barrow MA, Wilson LC, Brueton LA, Bonaglia MC, Hennekam RC, Eng C, Dennis NR, Trembath RC. Molecular analysis of 20 patients with 2q37.3 monosomy: definition of minimum deletion intervals for key phenotypes. J Med Genet. 2004 Jun;41(6):433-9. (
  • Alkuraya FS, Kimonis VE, Holt L, Murata-Collins JL. A patient with a ring chromosome 2 and microdeletion of 2q detected using FISH: Further support for "ring chromosome 2 syndrome". Am J Med Genet A. 2005 Feb 1;132A(4):447-9. Review. (
  • Casas KA, Mononen TK, Mikail CN, Hassed SJ, Li S, Mulvihill JJ, Lin HJ, Falk RE. Chromosome 2q terminal deletion: report of 6 new patients and review of phenotype-breakpoint correlations in 66 individuals. Am J Med Genet A. 2004 Nov 1;130A(4):331-9. (
  • Chaabouni M, Le Merrer M, Raoul O, Prieur M, de Blois MC, Philippe A, Vekemans M, Romana SP. Molecular cytogenetic analysis of five 2q37 deletions: refining the brachydactyly candidate region. Eur J Med Genet. 2006 May-Jun;49(3):255-63. Epub 2005 Aug 18. (
  • Czepulkowski B, Saunders K, Pocock C, Sadullah S. Mosaic trisomy 2 in myelodysplastic syndromes and acute myeloblastic leukemias. Cancer Genet Cytogenet. 2003 Aug;145(1):78-81. (
  • Dee SL, Clark AT, Willatt LR, Yates JR. A case of ring chromosome 2 with growth retardation, mild dysmorphism, and microdeletion of 2p detected using FISH. J Med Genet. 2001 Sep;38(9):E32. (
  • Ensembl Human Map View: Chromosome 2 (;r=2:1-242193529)
  • Falk RE, Casas KA. Chromosome 2q37 deletion: clinical and molecular aspects. Am J Med Genet C Semin Med Genet. 2007 Nov 15;145C(4):357-71. Review. (
  • Giardino D, Finelli P, Russo S, Gottardi G, Rodeschini O, Atza MG, Natacci F, Larizza L. Small familial supernumerary ring chromosome 2: FISH characterization and genotype-phenotype correlation. Am J Med Genet. 2002 Aug 15;111(3):319-23. (
  • Heller M, Provan D, Amess JA, Dixon-McIver A. Myelodysplastic syndrome associated with trisomy 2. Clin Lab Haematol. 2005 Aug;27(4):270-3. (
  • Hillier LW, Graves TA, Fulton RS, Fulton LA, Pepin KH, Minx P, Wagner-McPherson C, Layman D, Wylie K, Sekhon M, Becker MC, Fewell GA, Delehaunty KD, Miner TL, Nash WE, Kremitzki C, Oddy L, Du H, Sun H, Bradshaw-Cordum H, Ali J, Carter J, Cordes M, Harris A, Isak A, van Brunt A, Nguyen C, Du F, Courtney L, Kalicki J, Ozersky P, Abbott S, Armstrong J, Belter EA, Caruso L, Cedroni M, Cotton M, Davidson T, Desai A, Elliott G, Erb T, Fronick C, Gaige T, Haakenson W, Haglund K, Holmes A, Harkins R, Kim K, Kruchowski SS, Strong CM, Grewal N, Goyea E, Hou S, Levy A, Martinka S, Mead K, McLellan MD, Meyer R, Randall-Maher J, Tomlinson C, Dauphin-Kohlberg S, Kozlowicz-Reilly A, Shah N, Swearengen-Shahid S, Snider J, Strong JT, Thompson J, Yoakum M, Leonard S, Pearman C, Trani L, Radionenko M, Waligorski JE, Wang C, Rock SM, Tin-Wollam AM, Maupin R, Latreille P, Wendl MC, Yang SP, Pohl C, Wallis JW, Spieth J, Bieri TA, Berkowicz N, Nelson JO, Osborne J, Ding L, Meyer R, Sabo A, Shotland Y, Sinha P, Wohldmann PE, Cook LL, Hickenbotham MT, Eldred J, Williams D, Jones TA, She X, Ciccarelli FD, Izaurralde E, Taylor J, Schmutz J, Myers RM, Cox DR, Huang X, McPherson JD, Mardis ER, Clifton SW, Warren WC, Chinwalla AT, Eddy SR, Marra MA, Ovcharenko I, Furey TS, Miller W, Eichler EE, Bork P, Suyama M, Torrents D, Waterston RH, Wilson RK. Generation and annotation of the DNA sequences of human chromosomes 2 and 4. Nature. 2005 Apr 7;434(7034):724-31. (
  • Map Viewer: Genes on Sequence (,ugHs,genes&CHR=2)
  • Ostroverkhova NV, Nazarenko SA, Rubtsov NB, Nazarenko LP, Bunina EN. Characterization of a small supernumerary ring marker derived from chromosome 2 by forward and reverse chromosome painting. Am J Med Genet. 1999 Nov 26;87(3):217-20. Review. (
  • Stevens-Kroef M, Poppe B, van Zelderen-Bhola S, van den Berg E, van der Blij-Philipsen M, Geurts van Kessel A, Slater R, Hamers G, Michaux L, Speleman F, Hagemeijer A. Translocation t(2;3)(p15-23;q26-27) in myeloid malignancies: report of 21 new cases, clinical, cytogenetic and molecular genetic features. Leukemia. 2004 Jun;18(6):1108-14. (
  • UCSC Genome Browser: Statistics (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: April 2009
Published: November 23, 2015