Chromosome 2 (human)
Chromosome 2 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 2 is the second-largest human chromosome, spanning more than 242 million base pairs (the building material of DNA) and representing almost 8% of the total DNA in human cells.
Chromosome 2 contains the HOXD homeobox gene cluster.

# Evolution
All members of Hominidae except humans, Neanderthals, and Denisovans have 24 pairs of chromosomes. Humans have only 23 pairs of chromosomes. Human chromosome 2 is a result of an end-to-end fusion of two ancestral chromosomes.
The evidence for this includes:
- The correspondence of chromosome 2 to two ape chromosomes. The closest human relative, the chimpanzee, has near-identical DNA sequences to human chromosome 2, but they are found in two separate chromosomes. The same is true of the more distant gorilla and orangutan.
- The presence of a vestigial centromere. Normally a chromosome has just one centromere, but in chromosome 2 there are remnants of a second centromere in the q21.3q22.1 region.
- The presence of vestigial telomeres. These are normally found only at the ends of a chromosome, but in chromosome 2 there are additional telomere sequences in the q13 band, far from either end of the chromosome.
According to researcher J. W. IJdo, "We conclude that the locus cloned in cosmids c8.1 and c29B is the relic of an ancient telomere-telomere fusion and marks the point at which two ancestral ape chromosomes fused to give rise to human chromosome 2." 

# Genes

## Number of genes
The following are some of the gene count estimates of human chromosome 2. Because researchers use different approaches to genome annotation their predictions of the number of genes on each chromosome vary (for technical details, see gene prediction). Among various projects, the collaborative consensus coding sequence project (CCDS) takes an extremely conservative strategy. So CCDS's gene number prediction represents a lower bound on the total number of human protein-coding genes.
Some genes requiring arm identification:
- GEN1 encoding protein GEN1, Holliday junction 5' flap endonuclease
- PARD3B encoding protein Partitioning defective 3 homolog B
- PARK3 encoding protein Parkinson disease 3 (autosomal dominant, Lewy body)
- TSGA10 encoding protein Testis specific 10

## p-arm
The following are some of the genes located on p-arm (short arm) of human chromosome 2:
- ACTR2: encoding protein Actin-related protein 2
- ADI1: encoding enzyme 1,2-dihydroxy-3-keto-5-methylthiopentene dioxygenase
- AFF3: encoding protein AF4/FMR2 family member 3
- AFTPH: encoding protein Aftiphilin
- ALMS1
- ABCG5 and ABCG8: ATP-binding cassette, subfamily A, members 5 and 8
- C2orf18: encoding protein Transmembrane protein C2orf18
- C2orf28: encoding protein Apoptosis-related protein 3
- CAPG: capping acting protein
- CCDC142: Coiled-Coil Domain Containing 142
- CTLA4: cytotoxic T-Lymphocyte Antigen 4
- DHX57: DExH-box helicase 57
- DPYSL5: Dihydropyrimidinase like 5
- ERLEC1: Endoplasmic reticulum lectin 1
- EVA1A: encoding protein Eva-1 homolog A (C. elegans)
- FAM49A: Family with sequence similarity 49 member A
- FAM98A: Family with sequence similarity 98 member A
- FAM136A: Family with sequence similarity 136 member A
- FBXO11: F-box protein 11
- GFPT1: glutaminefructose-6-phosphate transaminase 1
- GKN1: gastrokine 1
- GPATCH11: G-patch domain containing protein 11
- GTF2A1L: General transcription factor IIA subunit 1 like
- HADHA: hydroxyacyl-Coenzyme A dehydrogenase/3-ketoacyl-Coenzyme A thiolase/enoyl-Coenzyme A hydratase (trifunctional protein), alpha subunit
- HADHB: hydroxyacyl-Coenzyme A dehydrogenase/3-ketoacyl-Coenzyme A thiolase/enoyl-Coenzyme A hydratase (trifunctional protein), beta subunit
- HSPC159: Galectin-related protein
- LEPQTL1: Leptin, serum levels of
- MEMO1: Mediator of cell motility 1
- MPHOSPH10: M-phase phosphoprotein 10
- MSH2: mutS homolog 2, colon cancer, nonpolyposis type 1 (E. coli)
- MSH6: mutS homolog 6 (E. coli)
- MTHFD2: Bifunctional methylenetetrahydrofolate dehydrogenase/cyclohydrolase, mitochondrial
- MTIF2: mitochondrial translational initiation factor 2
- NRBP1: Nuclear receptor-binding protein 1
- ODC1: Ornithine decarboxylase
- OTOF: otoferlin
- PCYOX1: prenylcysteine oxidase 1
- PELI1: Ubiquitin ligase
- PLGLB2: Plasminogen-related protein B
- POLR1A: DNA-directed RNA polymerase I subunit RPA1
- PREPL: Prolyl endopeptidase-like
- PXDN: Peroxidasin homolog
- QPCT: Glutaminyl-peptide cyclotransferase
- RETSAT: All-trans-retinol 13,14-reductase
- SH3YL1: SH3 and SYLF domain-containing 1
- TGOLN2: Trans-Golgi network integral membrane protein 2
- THADA: encoding protein Thyroid adenoma associated
- TIA1: TIA1 cytotoxic granule-associated RNA binding protein
- TMEM150: Transmembrane protein 150A
- TP53I3: Putative quinone oxidoreducatse
- TPO: thyroid peroxidase
- TTC7A: familial multiple intestinal atresia
- WBP1: WW domain-binding protein 1
- WDR35 (IFT121: TULP4): intraflagellar transport 121

## q-arm
The following are some of the genes located on q-arm (long arm) of human chromosome 2:
- ABCA12: ATP-binding cassette, sub-family A (ABC1), member 12
- ACTR1B: encoding protein Beta-centractin
- AGXT: alanine-glyoxylate aminotransferase (oxalosis I; hyperoxaluria I; glycolicaciduria; serine-pyruvate aminotransferase)
- ALS2: amyotrophic lateral sclerosis 2 (juvenile)
- ALS2CR8: encoding protein Amyotrophic lateral sclerosis 2 chromosomal region candidate gene 8 protein also known as calcium-response factor (CaRF)
- ARMC9: encoding protein LisH domain-containing protein ARMC9
- B3GNT7: encoding protein UDP-GlcNAc:betaGal beta-1,3-N-acetylglucosaminyltransferase 7
- BMPR2: bone morphogenetic protein receptor, type II (serine/threonine kinase)
- CCDC88A: Coiled-coil domain-containing protein 88A
- CCDC93: Coiled-coil domain-containing protein 93
- CCDC138: Coiled-coil domain-containing protein 138
- CDCA7: Cell division cycle associated protein 1
- CHPF: Chondroitin sulfate synthase 2
- COL3A1: collagen, type III, alpha 1 (Ehlers-Danlos syndrome type IV, autosomal dominant)
- COL4A3: collagen, type IV, alpha 3 (Goodpasture antigen)
- COL4A4: collagen, type IV, alpha 4
- COL5A2: collagen, type V, alpha 2
- DIS3L2: DIS3 mitotic control homolog-like 2
- ECEL1: Endothelin converting enzyme like 1
- EPC2: Enhancer of polycomb homolog 2
- EPB41L5: encoding protein Erythrocyte membrane protein band 4.1 like 5
- ERICH2: encoding protein Glutamate rich protein 2
- FASTKD1: FAST kinase domain-containing protein 1
- IMP4: U3 small nucleolar ribonucleoprotein
- INPP1: Inositol polyphosphate 1-phosphatase
- INPP4A: inositol polyphosphate-4-phosphatase type A
- ITM2C: Integral membrane protein 2C
- KANSL3:  KAT8 regulatory NSL complex subunit 3
- KIAA1211L: Uncharacterized Protein KIAA1211- Like
- LANCL1: LanC like 1
- MALL: MAL-like protein
- MGAT5: mannosyl (alpha-1,6-)-glycoprotein beta-1,6-N-acetyl-glucosaminyltransferase
- NABP1: Nucleic acid binding protein 1
- NEURL3: encoding protein Neuralized E3 ubiquitin protein ligase 3
- NCL: Nucleolin
- NR4A2: nuclear receptor subfamily 4, group A, member 2
- OLA1: Obg-like ATPase 1
- PAX3: paired box gene 3 (Waardenburg syndrome 1)
- PAX8: paired box gene 8
- POLR1B: DNA-directed RNA polymerase I subunit RPA2
- PRR21: Proline-rich protein 21
- PRSS56: Putative serine protease 56
- RIF1: replication timing regulatory factor 1
- RNU4ATAC: RNA, U4atac small nuclear (U12-dependent splicing)
- RPL37A: encoding protein 60S ribosomal protein L37a
- SATB2: Homeobox 2
- SDPR: Serum deprivation-response protein
- SGOL2: Shugoshin-like 2
- SH3BP4: SH3 domain-binding protein 4
- SLC9A4: solute carrier family 9 member A4
- SLC40A1: solute carrier family 40 (iron-regulated transporter), member 1
- SMPD4: Sphingomyelin phosphodiesterase 4
- SP140: encoding protein SP140 nuclear body protein
- SPATS2L: spermatogenesis associated, serine-rich 2-like protein
- SSB: Sjogren syndrome antigen B
- SSFA2: Sperm-specific antigen 2
- TBR1: T-box, brain, 1
- THAP4: THAP domain-containing protein 4
- TMBIM1: Transmembrane BAX inhibitor motif-containing protein 1
- TNRC15: PERQ amino acid-rich with GYF domain-containing protein 2
- TTN: titin
- UBXD2: UBX domain-containing protein 4
- UXS1: UDP-glucuronic acid decarboxylase 1
- XIRP2: Xin actin-binding repeat-containing protein 2
- ZNF142: zinc finger protein 142

# Related diseases and traits
The following diseases and traits are related to genes located on chromosome 2:
- 2p15-16.1 microdeletion syndrome
- Autism
- Alport syndrome
- Alstrom syndrome
- Amyotrophic lateral sclerosis
- Congenital hypothyroidism
- Crigler-Najjar types I/II
- Dementia with Lewy bodies
- EhlersDanlos syndrome
- EhlersDanlos syndrome, classical type
- EhlersDanlos syndrome, vascular type
- Fibrodysplasia ossificans progressiva
- Gilbert's syndrome
- Harlequin type ichthyosis
- Hemochromatosis
- Hemochromatosis type 4
- Hereditary nonpolyposis colorectal cancer
- Infantile-onset ascending hereditary spastic paralysis
- Juvenile primary lateral sclerosis
- Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency
- Maturity onset diabetes of the young type 6
- Mitochondrial trifunctional protein deficiency
- Nonsyndromic deafness
- Primary hyperoxaluria
- Primary pulmonary hypertension
- Sitosterolemia (knockout of either ABCG5 or ABCG8)
- Sensenbrenner syndrome
- Synesthesia
- Waardenburg syndrome

# Cytogenetic band