Fact-checked by Grok 2 weeks ago

Chromosome 20

Chromosome 20 is one of the 23 pairs of chromosomes in the human nucleus, with each cell typically containing two copies inherited from the parents. It is a small, metacentric chromosome spanning 64,444,167 base pairs in the GRCh38.p14 reference genome assembly, representing about 2% of the total DNA content in cells. The chromosome likely contains 500 to 600 genes that provide instructions for producing proteins involved in diverse functions, such as cell signaling, immune response, and developmental processes.^[1]^[2]^[3] Structurally, chromosome 20 consists of a short arm (p arm) and a long arm (q arm) separated by a centromere near the midpoint, with G-banding revealing distinct cytogenetic bands including 20p13 to 20p11.21 on the p arm and 20q11.21 to 20q13.33 on the q arm. These regions harbor genes critical for various physiological roles; for instance, the JAG1 gene at 20p12.2 encodes a protein essential for Notch signaling during embryonic development, and mutations in this gene cause Alagille syndrome, characterized by liver disease, heart defects, and distinctive facial features. Similarly, the ADA gene at 20q13.12 encodes adenosine deaminase, an enzyme vital for purine metabolism and immune function, with biallelic mutations leading to severe combined immunodeficiency (SCID).^[2]^[4]^[5] Chromosome 20 abnormalities are associated with several genetic disorders and cancers. Ring chromosome 20 syndrome, resulting from fusion of the chromosome's ends into a ring structure, often leads to epilepsy, intellectual disability, and behavioral issues due to gene dosage alterations. Deletions or duplications of material from chromosome 20 can cause developmental delays, intellectual disabilities, and physical anomalies. Notably, interstitial deletions on the q arm (del(20q)) are a recurrent abnormality in myeloid malignancies, including myelodysplastic syndromes, chronic myeloproliferative disorders, and acute myeloid leukemia, observed in up to 10% of cases and potentially indicating a tumor suppressor gene in this region. Additionally, the PRNP gene at 20p13 encodes the prion protein, and its mutations are linked to familial prion diseases like Creutzfeldt-Jakob disease, which cause progressive neurodegeneration.^[6]^[2]^[7]

Overview

Definition and Role

Chromosome 20 is one of the 23 pairs of chromosomes present in the nucleus of human cells, comprising the twentieth pair of autosomes. In typical human somatic cells, two copies of chromosome 20 are found—one inherited from each parent—forming part of the diploid set of 46 chromosomes that maintains genetic stability across cell divisions.^[2] Unlike the sex chromosomes (X and Y), which determine biological sex and exhibit distinct inheritance patterns, chromosome 20 functions as an autosome and pairs with its homologous partner during meiosis to facilitate the equitable distribution of genetic material to gametes. This pairing ensures that offspring receive one copy from each parent, preserving the balanced transmission of autosomal genetic information.^[8] Chromosome 20 plays a crucial role in encoding genetic instructions essential for human traits, embryonic development, and ongoing cellular processes. Its DNA is organized into chromatin, a tightly coiled structure of nucleic acids and proteins that compacts the genetic material while allowing regulated access for transcription and replication.^[8]

Karyotype Characteristics

Chromosome 20 is the 20th largest autosome in the human karyotype and belongs to group F, characterized as a small metacentric chromosome with nearly equal arm lengths.^[9] The centromere is positioned centrally, dividing the chromosome into a short arm (p arm, designated 20p) and a long arm (q arm, designated 20q), resulting in an arm ratio close to 1:1 that defines its metacentric morphology.^[10] In G-banded metaphase spreads, chromosome 20 measures approximately 2% of the total haploid genome length, providing a visual scale for its compact size relative to larger chromosomes like chromosome 1.^[2] G-banding, the standard cytogenetic staining method, reveals distinct patterns on chromosome 20 as outlined in the International System for Human Cytogenomic Nomenclature (ISCN). The p arm appears predominantly dark (G-positive), while the q arm is lighter (G-negative) overall, interrupted by two narrow, less intense dark bands, facilitating precise identification in karyotype analysis.^[11] ISCN nomenclature numbers bands and sub-bands outward from the centromere, such as 20p13 to 20p11.2 on the short arm and 20q11.2 to 20q13 on the long arm, standardizing descriptions across resolutions from 400 to 850 bands per haploid set.^[12]

Physical Structure

Size and Composition

Chromosome 20 in the human genome measures 64,444,167 base pairs in length according to the GRCh38.p14 assembly, representing approximately 2% of the total human genomic DNA, which spans about 3.1 billion base pairs.^[1] This metacentric chromosome is positioned as the 20th pair in the standard karyotype. The molecular composition of Chromosome 20 features a GC content of approximately 44%, which is slightly higher than the genome-wide average of 41%. The bulk of the chromosome consists of euchromatin, while heterochromatin is primarily restricted to the centromeric and telomeric regions, facilitating structural stability and gene regulation. At the centromere, located near the middle of the chromosome, large arrays of alpha satellite DNA predominate; these repetitive sequences, composed of 171-base-pair monomers organized into higher-order repeats spanning several megabases, are essential for kinetochore assembly and chromosome segregation during cell division.^[13] The telomeres, capping the ends of the p and q arms, comprise tandem repeats of the TTAGGG hexanucleotide motif, protecting against end-to-end fusions and degradation.^[14]

Cytogenetic Banding

Cytogenetic banding of human chromosome 20 is primarily achieved through G-banding, a technique that stains chromosomes with Giemsa after trypsin treatment to produce alternating dark (G-positive, AT-rich) and light (G-negative) bands reflective of chromatin condensation levels. The short arm (20p) displays major bands designated as 20p13 (distal), 20p12, and 20p11 (proximal to the centromere), while the long arm (20q) includes 20q11 (pericentromeric), 20q12, and 20q13 (telomeric). These bands follow the International System for Human Cytogenomic Nomenclature (ISCN) and facilitate gross structural analysis in karyotyping.^[15] At higher resolutions, such as the 850-band per haploid set (bphs) level, chromosome 20 reveals finer sub-bands, enhancing mapping precision for cytogenetic studies; for example, 20p12 often appears as a variable region with inconsistent staining or structural polymorphisms due to heterochromatic variability near the centromere. This level of detail, achieved through extended culture times and optimized staining protocols, distinguishes sub-bands like 20p12.1-p12.3 and 20q13.1-q13.3, aiding in the identification of subtle rearrangements.^[16] Functionally, the G-positive bands on chromosome 20, such as portions of 20p11 and 20q11, correspond to heterochromatic regions with low gene density, late replication timing, and high AT content, promoting chromatin compaction and transcriptional silencing. In contrast, G-negative interband regions, including parts of 20p13 and 20q13, are euchromatic, exhibiting higher gene density, GC richness, and early replication, which support active gene expression and house a disproportionate number of housekeeping genes. These band-specific properties influence overall chromosomal organization and stability.^[17] The banding techniques for chromosome 20 evolved from post-1970s refinements in cytogenetics, building on the 1971 Paris Conference standardization of G-banding, which replaced uniform staining with reproducible patterns; subsequent advancements, including high-resolution protocols in the 1980s, improved band resolution from ~400 to 850 bphs through actinomycin D or methotrexate synchronization, enabling detailed analysis specific to smaller chromosomes like 20.^[18]

Genetic Content

Number of Genes

Chromosome 20 contains an estimated 500 to 600 protein-coding genes, based on annotations from Ensembl and GENCODE as of 2025.^[2]^[19] These figures reflect rigorous curation processes that prioritize high-confidence predictions supported by experimental evidence, such as cDNA sequencing and proteomics data. The exact count varies slightly between databases due to differences in annotation criteria; for instance, GENCODE v47 reports 540 protein-coding loci, excluding readthrough transcripts.^[20] Beyond protein-coding genes, chromosome 20 includes significant numbers of non-coding RNAs and pseudogenes, with approximately 594 long non-coding RNA genes and 100 to 200 pseudogenes annotated in recent releases.^[19] Gene counting methods rely on standardized resources like RefSeq for curated transcripts, the Consensus Coding Sequence (CCDS) project for conserved coding regions across species, and integrated multi-omics data to distinguish functional elements from artifacts. These approaches ensure comprehensive coverage while minimizing over-annotation of unverified loci. Relative to the human genome average of about 800 protein-coding genes per autosome, chromosome 20 exhibits lower overall gene content but a comparable density of roughly 8 to 9 genes per megabase, given its approximately 64 million base pair length.^[2] This positioning highlights chromosome 20's intermediate role in genomic organization. Early sequencing efforts under the Human Genome Project completed the chromosome's euchromatic sequence in 2001, initially predicting around 700 genes, though later refinements reduced this based on functional validation. Contemporary updates from long-read assemblies, such as those in the Telomere-to-Telomere (T2T) consortium and GENCODE's incorporation of PacBio and Oxford Nanopore data, have enhanced accuracy by resolving repetitive regions and uncovering previously missed non-coding elements.^[20]

Notable Genes and Functions

Chromosome 20 harbors several notable genes with critical roles in cellular signaling, metabolism, DNA maintenance, and developmental processes. Among these, the GNAS complex locus at 20q13.32 encodes the stimulatory G-protein alpha subunit (Gsα), which plays a central role in G-protein-coupled receptor signaling by linking ligand-receptor interactions to the activation of adenylyl cyclase, thereby regulating cyclic AMP levels and mediating hormone responses across various tissues.^[21] This gene exhibits complex imprinting patterns, with parent-specific expression influencing its regulatory functions in development and homeostasis.^[21] The ADA gene, located at 20q13.12, encodes adenosine deaminase, an enzyme essential for purine metabolism that catalyzes the deamination of adenosine to inosine and deoxyadenosine to deoxyinosine, thereby preventing the accumulation of toxic purine intermediates during nucleotide catabolism.^[22] This process supports nucleic acid recycling and maintains cellular nucleotide balance, particularly in rapidly dividing cells.^[22] At 20q12, the TOP1 gene encodes DNA topoisomerase I, an enzyme that regulates DNA topology by creating transient single-strand breaks, allowing the rotation and passage of DNA segments to relieve supercoiling generated during transcription and replication.^[23] This function is vital for efficient gene expression and genomic stability, as it enables the unwinding of DNA helices without permanent damage.^[23] The BMP7 gene, situated at 20p12.3, encodes bone morphogenetic protein 7, a secreted member of the TGF-β superfamily that functions as a signaling ligand in mesenchymal cell differentiation and tissue morphogenesis.^[24] It promotes bone formation by inducing ectopic ossification and supports kidney development through regulation of epithelial-mesenchymal interactions and nephron patterning.^[24] Chromosome 20 also contains clusters of related genes, such as the type 2 cystatin family, which includes at least seven members encoding cysteine protease inhibitors involved in modulating proteolytic activity and extracellular matrix remodeling.^[25]

Associated Conditions

Inherited Disorders

Alagille syndrome is an autosomal dominant multisystem disorder primarily caused by heterozygous pathogenic variants in the JAG1 gene located at 20p12.2.^[26] It is characterized by a paucity of intrahepatic bile ducts leading to cholestasis and liver dysfunction, congenital heart defects such as peripheral pulmonary artery stenosis, distinctive facial features including broad forehead and deep-set eyes, posterior embryotoxon in the eyes, and butterfly-like vertebral arch defects.^[27] The estimated prevalence is approximately 1 in 30,000 live births.^[28] Diagnosis typically requires clinical findings meeting at least three of the five major criteria (cholestasis, cardiac disease, skeletal abnormalities, ocular anomalies, and characteristic facies) or identification of a pathogenic JAG1 variant, with genetic testing confirming the diagnosis in about 94% of cases.^[27] Adenosine deaminase (ADA) deficiency, resulting from biallelic pathogenic variants in the ADA gene at 20q13.12, is an autosomal recessive cause of severe combined immunodeficiency (SCID).^[5] This enzyme deficiency leads to toxic accumulation of deoxyadenosine and deoxyadenosine triphosphate, causing profound lymphopenia, impaired T-, B-, and NK-cell function, recurrent severe infections, and often failure to thrive beginning in early infancy.^[29] It accounts for 10-15% of SCID cases, with an overall prevalence of about 1 in 200,000 to 1,000,000 live births depending on population screening.^[30] Diagnostic criteria include clinical features of SCID, absent or low ADA enzyme activity in erythrocytes or fibroblasts, and molecular confirmation of ADA variants, with newborn screening via T-cell receptor excision circle (TREC) analysis enabling early detection.^[29] Ring chromosome 20 syndrome is a rare chromosomal disorder caused by the formation of a ring structure from chromosome 20, typically de novo, leading to partial monosomy of both arms. It is characterized by drug-resistant epilepsy, often starting in childhood with staring spells and behavioral issues, intellectual disability, and mild dysmorphic features. Prevalence is estimated at less than 1 in 100,000. Diagnosis involves karyotyping or chromosomal microarray confirming the ring.^[6]^[31] Mutations in the PRNP gene at 20p13 cause familial prion diseases, including familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), and fatal familial insomnia (FFI), which are autosomal dominant neurodegenerative disorders. These mutations lead to misfolding of the prion protein, resulting in progressive dementia, ataxia, myoclonus, and death typically within months to years. Prevalence of familial forms is about 1-2% of all prion diseases, or roughly 1 in 10 million annually. Diagnosis includes genetic testing for PRNP variants, EEG, MRI, and CSF analysis for 14-3-3 protein.^[32]^[33] Imprinting disorders associated with the GNAS complex locus at 20q13.32 arise from parent-of-origin-specific epigenetic defects affecting Gsα protein expression, leading to tissue-specific hormone resistance.^[34] Pseudohypoparathyroidism type 1A (PHP1A), an autosomal dominant condition due to maternal loss-of-function GNAS variants combined with paternal imprinting defects, manifests as resistance to parathyroid hormone causing hypocalcemia and hyperphosphatemia, along with Albright hereditary osteodystrophy (AHO) features such as short stature, brachydactyly, subcutaneous ossifications, and cognitive impairment.^[35] The prevalence is estimated at 0.34 to 1.1 per 100,000 individuals.^[36] Diagnosis involves elevated parathyroid hormone levels disproportionate to serum calcium, characteristic AHO signs, and genetic/methylation analysis confirming maternal GNAS defects; pseudopseudohypoparathyroidism (PPHP) occurs with paternal transmission, presenting AHO without hormone resistance.^[37]

Cancer Associations

Somatic alterations of chromosome 20, particularly amplifications of its long arm (20q), play a significant role in the oncogenesis of various solid tumors. In breast cancer, 20q amplification is frequently observed, often leading to overexpression of oncogenes within the amplified region that drive tumor progression. Similarly, in ovarian cancer, amplification and overexpression of the AURKA gene at 20q13 have been documented in both immortalized ovarian epithelial cells and primary tumors, correlating with increased mitotic instability and malignant transformation. Colorectal cancer also exhibits high rates of 20q gains, with amplification encompassing multiple potential oncogenes such as AURKA, which serves as a prognostic marker for invasive recurrence and poorer survival outcomes.^[38]^[39]^[40] Deletions of 20q represent another key somatic event, predominantly in hematological malignancies like myelodysplastic syndromes (MDS), observed in up to 10% of myeloid malignancies. Isolated del(20q) occurs in a subset of MDS cases and is linked to mutations in genes such as BCAS1, which acts as a leukemogenic driver when altered, particularly in patients progressing to acute myeloid leukemia. In pancreatic cancer, point mutations in GNAS at 20q13.32 are recurrent in intraductal papillary mucinous neoplasms (IPMNs), the most common neoplastic precursors to pancreatic ductal adenocarcinoma; these activating mutations result in persistent cAMP signaling, cystogenesis, and neoplastic progression.^[41]^[42]^[2] Across tumor genomes, 20q gains are prevalent, with pan-cancer analyses indicating their occurrence in approximately 20% of tumors, highlighting chromosome 20 as a genomic hotspot for copy number alterations. Prognostically, 20q amplification often portends adverse outcomes, such as reduced survival in colorectal and breast cancers, while gains of chromosome 20 in precursor B-cell acute lymphoblastic leukemia (B-ALL) are associated with relatively poor prognosis compared to other aneuploidies.^[43]^[44]^[45]

Research and Evolution

Historical Discovery

The discovery of human chromosomes, including chromosome 20, began with efforts to accurately determine the total number in human cells. In 1956, Joe Hin Tjio and Albert Levan published the first reliable count of 46 chromosomes in human somatic cells, correcting earlier estimates of 48, through improved culturing and staining techniques applied to lung fibroblasts and other tissues.^[46] This work provided the initial visualization of the full set of human chromosomes, distinguishing chromosome 20 as one of the smaller metacentric pairs based on size and morphology.^[47] Advancements in cytogenetic techniques in the early 1970s enabled more precise identification of individual chromosomes. The Paris Conference in 1971 established standardized nomenclature for G-banding patterns using Giemsa staining, which revealed characteristic light and dark bands on chromosome 20, facilitating its distinction from others and assignment of specific regions like 20q13.^[48] This banding system supported early gene mapping efforts; for instance, the adenosine deaminase (ADA) gene was assigned to chromosome 20 in 1974 using somatic cell hybrids, with its regional localization to 20q13.11 determined in 1987.^[49] During the 1980s, linkage analysis revolutionized genetic mapping on chromosome 20 through the use of restriction fragment length polymorphisms (RFLPs), as pioneered by Botstein et al. in 1980.^[50] By the late 1980s, workshops had confirmed assignments of about seven genes to chromosome 20.^[51] Victor McKusick played a pivotal role in these efforts through his cataloging in Mendelian Inheritance in Man (now OMIM), which systematically linked inherited disorders to chromosomal locations, including several on chromosome 20.^[52] The sequencing era arrived with the Human Genome Project; a draft of chromosome 20 was produced in the early 2000s, culminating in its near-complete euchromatic sequence of approximately 59 million base pairs reported in 2001 by the International Human Genome Sequencing Consortium.

Evolutionary Aspects and Current Studies

Chromosome 20 exhibits significant evolutionary conservation across mammals, particularly in its syntenic relationship with mouse chromosome 2, where extensive sequence homology is observed in coding, repetitive, and non-coding intergenic regions.^[53] This conservation extends to primates, as evidenced by comparative mapping using BAC/PAC probes that trace the chromosome's evolutionary history through lineage-specific rearrangements and breakpoint reuse.^[54] Such synteny underscores the stability of chromosomal architecture over millions of years, facilitating cross-species functional studies in developmental biology and disease modeling. Human-specific features on chromosome 20 include complex imprinted regions, notably the GNAS locus at 20q13.11, which demonstrates tissue-specific imprinting patterns involving alternative transcripts and parent-of-origin-dependent expression.^[55] This locus encodes multiple proteins, such as Gsα, with imprinting regulated by differential DNA methylation that is conserved between humans and mice but manifests unique human disease associations when disrupted.^[56] While Neanderthal introgression contributes to modern human genomes broadly, specific variants on chromosome 20 remain under investigation, with no uniquely adaptive haplotypes identified to date.^[57] Ongoing research leverages CRISPR/Cas9 editing to address 20q-related abnormalities, particularly in human pluripotent stem cells where gains in the 20q region are common during genome editing and clonal expansion.^[58] These studies monitor genomic stability to mitigate p53-activating stressors that select for 20q amplifications, informing safer therapeutic editing for associated disorders.^[59] Post-2020 advances in single-cell sequencing have enhanced resolution of chromosome 20's cellular heterogeneity, enabling droplet-based RNA profiling to decode transcriptomic variations in imprinted regions like GNAS across cell types.^[60] As of 2025, integration with human pangenome projects has revealed population-specific variants across the genome, including structural variants and cryptic pathogenic alleles not captured in linear references, aiding equitable genomic medicine.^[61] The 2022 Telomere-to-Telomere (T2T) Consortium completed the first fully gap-free sequence of a human genome, including chromosome 20, resolving complex repetitive regions previously missing from GRCh38.^[62] In functional genomics, epigenetic regulation of non-coding elements on chromosome 20, such as those controlling GNAS imprinting control regions, involves long-range chromatin interactions and DNA methylation that fine-tune gene expression.^[63] This underscores the role of non-coding RNAs and enhancers in modulating tissue-specific functions, with comparative epigenetics revealing conserved yet diverged regulatory landscapes across species.^[64]

References

[1]
Human Genome Assembly GRCh38.p14 - NCBI - NIH
Human Genome Assembly GRCh38.p14 ; 20, 64,444,167, CM000682.2 · NC_000020.11 ; 21, 46,709,983, CM000683.2 · NC_000021.9.
[2]
Chromosome 20: MedlinePlus Genetics
### Key Facts About Human Chromosome 20
[3]
The DNA sequence and comparative analysis of human ... - PubMed
The finished sequence of human chromosome 20 comprises 59187298 base pairs (bp) and represents 99.4% of the euchromatic DNA ... metacentric chromosome. An add …
[4]
https://medlineplus.gov/genetics/gene/jag1/
[5]
ADA gene: MedlinePlus Genetics
May 21, 2024 · The ADA gene provides instructions for producing the enzyme adenosine deaminase. Learn about this gene and related health conditions.
[6]
https://medlineplus.gov/genetics/condition/ring-chromosome-20-syndrome/
[7]
Mosaic chromosome 20q deletions are more frequent in the aging ...
Feb 13, 2017 · Deletion of the long arm of chromosome 20, del(20q), is a common chromosomal abnormality in hematologic malignancies, observed in 10% of ...
[8]
Chromosome - National Human Genome Research Institute (NHGRI)
Chromosomes are threadlike structures made of protein and a single molecule of DNA that serve to carry the genomic information from cell to cell.Cromosoma · Histone · NucleosomeMissing: 20 | Show results with:20
[9]
Chapter 3. Chromosomal Composition and Nomenclature
Metacentric: In this type of chromosome the arms are of equal length. Human chromosomes 1, 3, 16, 19, 20 are metacentric. Submetacentric: In this type of ...
[10]
What are the major types of chromosomes? - AAT Bioquest
Jan 11, 2023 · Human chromosomes 1, 3, 16, 19, and 20 are metacentric. Submetacentric Chromosomes. In submetacentric chromosomes, the centromere is slightly ...
[11]
[PDF] Chapter 3 Human Chromosome Analysis
Chromosome 20 (Group F): Metacentric; p arm dark; q arm light, with two narrow, less intense dark bands. Chromosome 21 (Group G): Acrocentric; p arm with ...
[12]
An International System for Human Cytogenomic Nomenclature (2016)
phologic features important in identifying chromosomes. Landmarks include the ends of the chromosome arms, the centromere, and certain bands. The bands and ...
[13]
Complete genomic and epigenetic maps of human centromeres
Apr 1, 2022 · Human centromeres are located within large arrays of tandemly repeated DNA sequences known as alpha satellite (αSat), which often span millions ...
[14]
Chromosome Map - Genes and Disease - NCBI Bookshelf - NIH
Chromosome 20 · Contains over 900 genes · Contains over 60 million base pairs, of which over 90% have been determined · See the diseases associated with chromosome ...
[15]
20 - Chromosome Explorer
Chromosome 20. Chromosome 20 : G-banding, diagram and R-banding - Claude ... t(8;20)(p11;q13), KAT6A::NCOA3, 8 p11, 20 q13, Link to Pubmed · dic(9;20)(p11-13;q11) ...Missing: ideogram | Show results with:ideogram
[16]
The hierarchically organized splitting of chromosomal bands for all ...
Here we present for the first time the hierarchically organized splitting of chromosomal bands in their sub-bands for all human chromosomes.
[17]
Gene density in the Giemsa bands of human chromosomes - PubMed
Here, we investigated the GC levels, replication timings and DNA compaction of G(iemsa) bands. We showed that G bands comprise two different subsets of bands ...Missing: 20 | Show results with:20
[18]
History and evolution of cytogenetics - PMC - PubMed Central - NIH
Mar 20, 2015 · In the 1970s various chromosome banding techniques were introduced (see below) and these show that G- and Q-bands are associated with A-T rich ...
[19]
GENCODE - Human Release Statistics
### Summary of GENCODE Release 49 (GRCh38) Statistics for Chromosome 20
[20]
GENCODE 2025: reference gene annotation for human and mouse
Nov 20, 2024 · This first human release contains an average of two transcripts per protein-coding gene and will now become the default annotation view in the ...
[21]
2778 - Gene ResultGNAS GNAS complex locus [ (human)] - NCBI
Sep 27, 2025 · RT-PCR analysis of ovarian cancer samples revealed that high mRNA expression levels of the GNAS genes, located at chromosome 20q13, was ...
[22]
ADA adenosine deaminase [Homo sapiens (human)] - Gene - NCBI
- **Cytogenetic Location**: 20q13.12
[23]
7150 - Gene ResultTOP1 DNA topoisomerase I [ (human)] - NCBI
Sep 14, 2025 · This gene encodes a DNA topoisomerase, an enzyme that controls and alters the topologic states of DNA during transcription.
[24]
Gene ResultBMP7 bone morphogenetic protein 7 [ (human)] - NCBI
Sep 5, 2025 · BMP7 encodes a secreted ligand involved in bone, kidney, and brown adipose tissue development, and may promote fracture healing.
[25]
The human type 2 cystatin gene family consists of eight to ... - PubMed
The human type 2 cystatin gene family consists of eight to nine members, with at least seven genes clustered at a single locus on human chromosome 20.
[26]
Entry - #118450 - ALAGILLE SYNDROME 1; ALGS1 - (OMIM.ORG)
... gene (JAG1; 601920) on chromosome 20p12. ▽ Description. Alagille syndrome is an autosomal dominant disorder that traditionally has been defined by a paucity ...
[27]
Alagille Syndrome - GeneReviews® - NCBI Bookshelf
Jan 4, 2024 · JAG1-related autosomal dominant Charcot-Marie-Tooth hereditary neuropathy (OMIM 619574). This disease-gene relationship is based on a single ...
[28]
Alagille Syndrome - Symptoms, Causes, Treatment | NORD
The incidence of Alagille syndrome has been estimated to be approximately 1 in 30,000-45,000 individuals in the general population.
[29]
Adenosine Deaminase Deficiency - GeneReviews® - NCBI Bookshelf
Oct 3, 2006 · The protein encoded by ADA (chromosome locus 20q13.12) that is absent in ADA-SCID has, in recent years, been referred to as adenosine deaminase ...
[30]
ADA SCID - Immunodeficiency Search
Adenosine Deaminase (ADA) Deficiency is the second most common cause of SCID (it accounts 20% of all cases). The incidence is 1 in 200,000 live births. It ...<|control11|><|separator|>
[31]
Entry - *139320 - GNAS COMPLEX LOCUS - OMIM
GNAS is a complex imprinted locus that produces multiple transcripts through the use of alternative promoters and alternative splicing.
[32]
103580 - PSEUDOHYPOPARATHYROIDISM, TYPE IA; PHP1A
Pseudohypoparathyroidism is a term applied to a heterogeneous group of disorders whose common feature is end-organ resistance to parathyroid hormone (PTH; ...
[33]
A patient with pseudohypoparathyroidism type 1A previously ...
Jul 28, 2022 · It is estimated that the prevalence of PHP is approximately 0.34-1.1 per 100,000 (2-4). In patients with normal renal function, ...
[34]
Disorders of GNAS Inactivation - GeneReviews® - NCBI Bookshelf
Oct 26, 2017 · Pseudohypoparathyroidism (PHP) Ia, Ib, and Ic result from reduced or absent expression/function of the protein Gsα (encoded by the maternal GNAS ...
[35]
Breast cancer risk associated with AURKA 91T → A polymorphism ...
The AURKA gene is located on chromosome 20q13 [3] and is ... gene BTAK on chromosome 20q13 is amplified and overexpressed in human breast cancer cell lines ...Missing: 20q | Show results with:20q
[36]
Amplification and overexpression of aurora kinase A (AURKA) in ...
... ovarian cancers. ... The degree of overexpression of AURKA was shown to be closely associated with the amplification of chromosome 20q in immortalized HOSE cells.
[37]
Aurora Kinase A Is a Prognostic Marker in Colorectal Adenocarcinoma
No reports on FISH for AURKA gene amplification in colorectal carcinoma ... Multiple putative oncogenes at the chromosome 20q amplicon contribute to colorectal ...
[38]
Somatic Mutations of the Breast Cancer Amplified Sequence-1 ...
Dec 6, 2014 · We found recurrent BCAS1 P488Q mutation in 10/56 (18%) of MDS with del(20q) pts who evolved to high risk disease and AML (sAML).
[39]
Recurrent GNAS Mutations Define an Unexpected Pathway for ... - NIH
In addition to defining a new pathway for pancreatic neoplasia, these data suggest that GNAS mutations can inform the diagnosis and management of patients with ...Missing: Chromosome | Show results with:Chromosome
[40]
Pan-caner analysis identifies PSMA7 as a targets for amplification at ...
Feb 6, 2024 · The chromosome 20 long arm (20q) is one of the genomic hotspots where copy number alterations frequently occur in multiple types of tumors.
[41]
Aurora Kinase A Is an Independent Predictor of Invasive Recurrence ...
Dec 20, 2022 · The AURKA gene is localized on chromosome segment 20q13, which is amplified in many human cancers [13‒15]. Ectopic overexpression of the kinase ...
[42]
Prognostic and Predictive Biomarkers in Precursor B-cell Acute ...
Trisomy 18 also has been associated with a favorable prognosis, while gain of extra copies of chromosomes 5 and 20 has been associated with relatively poor ...
[43]
THE CHROMOSOME NUMBER OF MAN - TJIO - 1956 - Hereditas
Levan, A. 1956. Chromosome studies on some human tumors and tissues of normal origin, grown in vivo and in vitro at the Sloan-Kettering Institute.
[44]
1955: 46 Human Chromosomes
Apr 23, 2013 · Joe Hin Tjio defined 46 as the exact number of human chromosomes. Tjio, an NIH researcher, was interested in the chromosomes of cancer cells.
[45]
Paris Conference (1971): Standardization in Human Cytogenetics
Characterization of Chromosomes by Other Banding Techniques 328. Proposed Chromosome Band Nomenclature 332. Identification of Chromosome Landmarks and Bands.
[46]
Assignment of a Gene for Adenosine Deaminase to Human ...
Abstract. Evidence, based on five series of mouse-human somatic cell hybrid clones, is presented for assignment of a human gene for adenosine deaminase ...
[47]
[PDF] Construction of a Genetic Linkage Map in Man Using Restriction ...
Although it is possible to detect linkage among simple Mendelian traits in humans, no method of systematically mapping human genes has been devised, largely ...
[48]
The map of chromosome 20 - PMC - PubMed Central - NIH
Five mutated genes on chromosome 20 have a relation to disease: a mutation in the adenosine deaminase gene results in a deficiency of the enzyme and severe ...
[49]
A 60-Year Tale of Spots, Maps, and Genes | Annual Reviews
Sep 22, 2006 · Abstract This is an account of almost 60 years' experience in the clinical delineation of genetic disorders, mapping genes on chromosomes, ...
[50]
Examination of sequence homology between human chromosome ...
Human Chr 20 shares intense conservation of coding, repetitive, and non-coding intergenic sequences with the congenic region of mouse Chr 2 including in the BSB ...<|separator|>
[51]
Evolutionary History of Chromosome 20 - Oxford Academic
In the present paper, we report the evolutionary history of human chromosome 20 in primates studied using a panel of BAC/PAC probes spaced along the chromosome.
[52]
tissue-specific imprinting and imprinting mutations in the GNAS locus
Aug 15, 2010 · The GNAS locus on chromosome 20q13.11 is the archetypal complex imprinted locus. It comprises a bewildering array of alternative transcripts.Missing: features | Show results with:features
[53]
The GNAS complex locus and human diseases associated with loss ...
The imprinted GNAS gene is located on the long arm of chromosome 20 in humans [1]. ... Encoded by GNAS exons 1–13 is Gsα, which is a ubiquitously expressed ...Mouse Models Of Php Ia · Figure 2 · Gnas-As1 Transcript
[54]
The Contribution of Neanderthal Introgression to Modern Human Traits
An adaptive Neanderthal OAS haplotype is observed at ~30% frequency in European and South Asian populations, and at 20% frequency in populations in East Asian ...
[55]
Recurrent Genetic Abnormalities in Human Pluripotent Stem Cells
Jan 14, 2020 · Cell reprogramming and genome editing using CRISPR/Cas9 require clonal expansion/selection that favors the emergence of abnormal clones. The iCS ...
[56]
Monitoring hPSC Genomic Stability in the Chromosome 20q Region ...
May 3, 2024 · Gene editing procedures warrant especially close monitoring of 20q genomic stability because they involve p53-activating stressors that ...
[57]
Droplet-based single-cell RNA sequencing: decoding cellular ...
Oct 14, 2025 · Droplet-based single-cell RNA sequencing (scRNA-seq) has redefined biological research by resolving cellular heterogeneity with an ...
[58]
Resource Complete reference genome and pangenome improve ...
Jun 24, 2025 · The pangenome reference further expands CpG calling by 4.5% in short-read sequencing data and identifies cross-population and population- ...
[59]
[PDF] Pangenome-based identification of cryptic pathogenic variants in ...
Jul 11, 2025 · Population-level TR variants were extracted from the intersection between these TR ... genome project. Lancet Reg Health West Pac. 2025;55:101473.
[60]
The long-range interaction between two GNAS imprinting control ...
Feb 28, 2023 · Abnormal GNAS imprinting causes pseudohypoparathyroidism type 1B (PHP1B), a prototype of mammalian end-organ hormone resistance. Hypomethylation ...
[61]
Discovery of cell-type specific regulatory elements in the human ...
These results highlight the potential regulatory roles of non-coding regions and, also, the power of a comparative epigenetics strategy in investigating ...Materials And Methods · Mapping Csre Bins To Various... · Results