{{short description|Region of sexual chromosomes exhibiting an autosomal inheritance pattern}} [[Image:A region in the pseudoautosomal region of the short arms of the X- and Y-chromosome.jpg|thumb|Detail of a human metaphase spread. A region in the pseudoautosomal region of the short arms of the X chromosome (left) and the Y chromosome (top right) was detected by fluorescent in situ hybridization (green). Chromosomes counterstained in red.]] The '''pseudoautosomal regions''' or '''PARs''' are homologous sequences of nucleotides found within the sex chromosomes of species with an XY<ref>{{Cite journal |last=Graves |first=J. |date=1998-12-01 |title=The origin and evolution of the pseudoautosomal regions of human sex chromosomes |url=https://academic.oup.com/hmg/article-lookup/doi/10.1093/hmg/7.13.1991 |journal=Human Molecular Genetics |volume=7 |issue=13 |pages=1991–1996 |doi=10.1093/hmg/7.13.1991|pmid=9817914 |url-access=subscription }}</ref> or ZW<ref>{{Cite journal |last1=Smeds |first1=Linnéa |last2=Kawakami |first2=Takeshi |last3=Burri |first3=Reto |last4=Bolivar |first4=Paulina |last5=Husby |first5=Arild |last6=Qvarnström |first6=Anna |last7=Uebbing |first7=Severin |last8=Ellegren |first8=Hans |date=2014-11-07 |title=Genomic identification and characterization of the pseudoautosomal region in highly differentiated avian sex chromosomes |journal=Nature Communications |language=en |volume=5 |issue=1 |pages=5448 |doi=10.1038/ncomms6448 |pmid=25378102 |bibcode=2014NatCo...5.5448S |issn=2041-1723|pmc=4272252 }}</ref> mechanism of sex determination.
The pseudoautosomal regions get their name because any genes within them (so far at least 29 have been found for humans)<ref>{{cite journal |vauthors=Blaschke RJ, Rappold G | year = 2006 | title = The pseudoautosomal regions, SHOX and disease | journal = Curr Opin Genet Dev | volume = 16 | issue = 3| pages = 233–9 | pmid = 16650979 | doi=10.1016/j.gde.2006.04.004}}</ref> are inherited just like any autosomal genes. In humans, these regions are referred to as PAR1 and PAR2.<ref>{{cite journal|last=Mangs|first=Helena|author2=Morris BJ |title=The Human Pseudoautosomal Region (PAR): Origin, Function and Future.|journal=Current Genomics|year=2007|volume=8|issue=2|pmid=18660847|doi=10.2174/138920207780368141|pmc=2435358|pages=129–136}}</ref> PAR1 comprises 2.6 Mbp of the short-arm tips of both X and Y chromosomes in humans and great apes (X and Y are 154 Mbp and 62 Mbp in total). PAR2 is at the tips of the long arms, spanning 320 kbp.<ref name="pmid18660847">{{cite journal |vauthors=Helena Mangs A, Morris BJ |title=The Human Pseudoautosomal Region (PAR): Origin, Function and Future |journal=Curr. Genomics |volume=8 |issue=2 |pages=129–36 |date=April 2007 |pmid=18660847 |pmc=2435358 |doi= 10.2174/138920207780368141}}</ref> The monotremes, including the platypus and echidna, have a multiple sex chromosome system, and consequently have 8 pseudoautosomal regions.<ref>{{Cite journal |last1=Zhou |first1=Yang |last2=Shearwin-Whyatt |first2=Linda |last3=Li |first3=Jing |last4=Song |first4=Zhenzhen |last5=Hayakawa |first5=Takashi |last6=Stevens |first6=David |last7=Fenelon |first7=Jane C. |last8=Peel |first8=Emma |last9=Cheng |first9=Yuanyuan |last10=Pajpach |first10=Filip |last11=Bradley |first11=Natasha |last12=Suzuki |first12=Hikoyu |last13=Nikaido |first13=Masato |last14=Damas |first14=Joana |last15=Daish |first15=Tasman |date=April 2021 |title=Platypus and echidna genomes reveal mammalian biology and evolution |journal=Nature |language=en |volume=592 |issue=7856 |pages=756–762 |doi=10.1038/s41586-020-03039-0 |pmid=33408411 |pmc=8081666 |bibcode=2021Natur.592..756Z |issn=1476-4687}}</ref>
==Location== thumb|400px|Pseudoautosomal regions are at both termini of the sex chromosomes. The locations of the PARs within GRCh38 are:<ref name="GRC38 overview">{{cite web|url=https://www.ncbi.nlm.nih.gov/grc/human|title=Human genome overview GRCh38.p10|author=Genome Reference Consortium|date=2017-01-06|access-date=2017-05-10|author-link=Genome Reference Consortium}}</ref> {|class="wikitable" style="text-align:right" ! Name !! Chromosome !! Basepair start !! Basepair stop !! Band<ref name="HUGO Gene Nomenclature Committee">{{cite web | title=Pseudoautosomal regions Gene Family | website=HUGO Gene Nomenclature Committee | url=https://www.genenames.org/cgi-bin/genefamilies/set/714 | access-date=2017-05-11}}</ref> |- |rowspan="2"| PAR1 || X || {{val|10001|fmt=commas}} || {{val|2781479|fmt=commas}} || Xp22 |- | Y || {{val|10001|fmt=commas}} || {{val|2781479|fmt=commas}} || Yp11 |- |rowspan="2"| PAR2 || X || {{val|155701383|fmt=commas}} || {{val|156030895|fmt=commas}} || Xq28 |- | Y || {{val|56887903|fmt=commas}} || {{val|57217415|fmt=commas}} || Yq12 |}
The locations of the PARs within GRCh37 are: {|class="wikitable" style="text-align:right" ! Name !! Chromosome !! Basepair start !! Basepair stop |- |rowspan="2"| PAR1 || X || {{val|60001|fmt=commas}} || {{val|2699520|fmt=commas}} |- | Y || {{val|10001|fmt=commas}} || {{val|2649520|fmt=commas}} |- |rowspan="2"| PAR2 || X || {{val|154931044|fmt=commas}} || {{val| 155260560|fmt=commas}} |- | Y || {{val|59034050|fmt=commas}} || {{val|59363566|fmt=commas}} |}
==Inheritance and function== Normal male therian mammals have two copies of these genes: one in the pseudoautosomal region of their Y chromosome, the other in the corresponding portion of their X chromosome. Normal females also possess two copies of pseudoautosomal genes, as each of their two X chromosomes contains a pseudoautosomal region. Crossing over between the X and Y chromosomes is normally restricted to the pseudoautosomal regions; thus, pseudoautosomal genes exhibit an autosomal, rather than sex-linked, pattern of inheritance. So, females can inherit an allele originally present on the Y chromosome of their father.
The function of these pseudoautosomal regions is that they allow the X and Y chromosomes to pair and properly segregate during meiosis in males.<ref name="pmid10655549">{{cite journal |vauthors=Ciccodicola A, D'Esposito M, Esposito T, etal |title=Differentially regulated and evolved genes in the fully sequenced Xq/Yq pseudoautosomal region |journal=Hum. Mol. Genet. |volume=9 |issue=3 |pages=395–401 |date=February 2000 |pmid=10655549 |doi= 10.1093/hmg/9.3.395|doi-access=free }}</ref>
==Genes== [[File:Pseudoautosomal Regions and Genes.jpg|thumb|350px|PAR1 contains 16 genes, with PLCXD1 as the furthermost PAR1 gene at the distal telomeric end and XG at the boundary of PAR1 at the centromeric end. PAR2 contains 3 genes, with SPRY3 at the centromeric boundary and IL9R at the distal telomeric end.<ref name="pmid27655702">{{cite journal | vauthors = Weng S, Stoner SA, Zhang DE | year = 2016 | title = Sex chromosome loss and the pseudoautosomal region genes in hematological malignancies | journal = Oncotarget | volume = 7 | issue = 44| pages = 72356–72372 | doi = 10.18632/oncotarget.12050 | pmid = 27655702 | pmc=5342167}}</ref>]] Pseudoautosomal genes are found in two different locations: PAR1 and PAR2. These are believed to have evolved independently.<ref name="pmid12566406">{{cite journal |vauthors=Charchar FJ, Svartman M, El-Mogharbel N, etal |title=Complex events in the evolution of the human pseudoautosomal region 2 (PAR2) |journal=Genome Res. |volume=13 |issue=2 |pages=281–6 |date=February 2003 |pmid=12566406 |pmc=420362 |doi=10.1101/gr.390503 }}</ref>
===PAR1=== * pseudoautosomal PAR1<ref name="HUGO PAR1">{{cite web | title=Pseudoautosomal region 1 (PAR1) Gene Family | website=HUGO Gene Nomenclature Committee | url=https://www.genenames.org/cgi-bin/genefamilies/set/715 | access-date=2017-05-12}}</ref> ** AKAP17A ** ASMT ** ASMTL ** CD99 ** CRLF2 ** CSF2RA ** DHRSX ** GTPBP6 ** IL3RA ** P2RY8 ** PLCXD1 ** PPP2R3B ** SHOX ** SLC25A6 ** XG, which straddles the PAR1 region boundary ** ZBED1
in mice, some PAR1 genes have transferred to autosomes.<ref name="pmid18842153">{{cite journal |vauthors=Levy MA, Fernandes AD, Tremblay DC, Seah C, Bérubé NG |title=The SWI/SNF protein ATRX co-regulates pseudoautosomal genes that have translocated to autosomes in the mouse genome |journal=BMC Genomics |volume=9|pages=468 |year=2008 |pmid=18842153 |pmc=2577121 |doi=10.1186/1471-2164-9-468 |doi-access=free }}</ref>
===PAR2=== * pseudoautosomal PAR2<ref name="HGNC PAR2">{{cite web | title=Pseudoautosomal region 2 (PAR2) Gene group | website=HUGO Gene Nomenclature Committee | url=https://www.genenames.org/data/genegroup/#!/group/716 | access-date=2019-08-30}}</ref> ** IL9R ** SPRY3 ** VAMP7, also known as SYBL1 ** CXYorf1, also known as FAM39A and now mapped to the pseudogene WASH6P,<ref name="urlWASH6P">{{cite web |url=https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:31685 |title=WASH6P |website=HUGO Gene Nomenclature Committee |access-date=2019-08-30}}</ref> but of interest due to its proximity to the telomere.<ref name="pmid10655549" />
==Pathology== Pairing (synapsis) of the X and Y chromosomes and crossing over (recombination) between their pseudoautosomal regions appear to be necessary for the normal progression of male meiosis.<ref>{{cite journal|last1=Eichner|first1=E.M.|title=The mouse Y* chromosome involves a complex rearrangement including interstitial positioning of the Y-pseudoautosomal region|journal=Cytogenetics and Cell Genetics|date=February 1991|volume=57|issue=4|pages=221–230|doi=10.1159/000133152|pmid=1743079}}</ref> Thus, those cells in which X-Y recombination does not occur will fail to complete meiosis. Structural and/or genetic dissimilarity (due to hybridization or mutation) between the pseudoautosomal regions of the X and Y chromosomes can disrupt pairing and recombination, and consequently cause male infertility.
The SHOX gene in the PAR1 region is the gene most commonly associated with and well understood with regards to disorders in humans,.<ref name="pmid16650979">{{cite journal |vauthors=Blaschke RJ, Rappold G |title=The pseudoautosomal regions, SHOX and disease |journal=Curr. Opin. Genet. Dev. |volume=16 |issue=3 |pages=233–9 |date=June 2006 |pmid=16650979 |doi=10.1016/j.gde.2006.04.004 }}</ref>
Deletions have also been associated with Léri-Weill dyschondrosteosis<ref name="pmid16175500">{{cite journal |vauthors=Benito-Sanz S, Thomas NS, Huber C, etal |title=A novel class of Pseudoautosomal region 1 deletions downstream of SHOX is associated with Leri-Weill dyschondrosteosis |journal=Am. J. Hum. Genet. |volume=77 |issue=4 |pages=533–44 |date=October 2005 |pmid=16175500 |pmc=1275603 |doi=10.1086/449313 }}</ref> and Madelung's deformity.
==See also== * Interleukin-3 receptor * Interleukin-9 receptor
==References== {{reflist|30em}}
==External links== {{Commons category|Pseudoautosomal region}} * {{Gene|PABX}} * {{Gene|PABY}}
{{Chromosomes}}
Category:Molecular genetics Category:Cytogenetics