Editing Autosome (section)

{{short description|Any chromosome other than a sex chromosome}}
{{About|a type of chromosome|the ancestral discovery method using autosomal DNA|Genealogical DNA test#Geographic origin tests}}

An '''autosome''' is any [[chromosome]] that is not a [[sex chromosome]].<ref>{{Cite book | last1=Griffiths | first1=Anthony J. F. | title=An Introduction to genetic analysis | year=1999 | publisher=W.H. Freeman | location=New York  | isbn=978-0-7167-3771-1 | url=https://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=autosome&rid=iga.section.222}}</ref> The members of an autosome pair in a [[diploid]] cell have the same [[Morphology (biology)|morphology]], unlike those in [[allosome|allosomal]] ([[sex chromosome]]) pairs, which may have different structures. The [[DNA]] in autosomes is collectively known as '''atDNA''' or '''auDNA'''.<ref>{{cite web|url=http://www.isogg.org/wiki/Autosomal_DNA|title=Autosomal DNA - ISOGG Wiki|website=www.isogg.org|access-date=28 April 2018|url-status=live|archive-url=https://web.archive.org/web/20170821085342/https://isogg.org/wiki/Autosomal_DNA|archive-date=21 August 2017}}</ref>

For example, [[human]]s have [[Human genome|a diploid genome]] that usually contains 22 pairs of autosomes and one [[allosome]] pair (46 chromosomes total). The autosome pairs are labeled with numbers (1–22 in humans) roughly in order of their sizes in base pairs, while allosomes are labelled with their letters.<ref>{{cite web|url=http://ghr.nlm.nih.gov/glossary=autosome|title=Autosome Definition(s)|website=Genetics Home Reference|access-date=28 April 2018|url-status=dead|archive-url=https://web.archive.org/web/20160102070828/http://ghr.nlm.nih.gov/glossary=autosome|archive-date=2 January 2016}}</ref> By contrast, the allosome pair consists of two [[X chromosome]]s in females or one X and one [[Y chromosome]] in males. Unusual combinations [[XYY syndrome|XYY]], [[Klinefelter syndrome|XXY]], [[Triple X syndrome|XXX]], [[XXXX syndrome|XXXX]], [[XXXXX syndrome|XXXXX]] or [[XXYY syndrome|XXYY]], among other irregular combinations, are known to occur and usually cause developmental abnormalities.

Autosomes still contain sexual determination [[genes]] even though they are not sex chromosomes. For example, the [[SRY]] gene on the Y chromosome encodes the transcription factor [[Testis determining factor|TDF]] and is vital for male sex determination during development. TDF functions by activating the [[SOX9]] gene on [[Chromosome 17 (human)|chromosome 17]], so mutations of the [[SOX9]] gene can cause humans with an ordinary Y chromosome to develop as females.<ref name="pmid7990924">{{cite journal | vauthors = Foster JW, Dominguez-Steglich MA, Guioli S, Kwok C, Weller PA, Stevanović M, Weissenbach J, Mansour S, Young ID, Goodfellow PN | title = Complicate dysplasia and autosomal sex reversal caused by mutations in an SRY-related gene | journal = Nature | volume = 372 | issue = 6506 | pages = 525–30 | date = December 1994 | pmid = 7990924 | doi = 10.1038/372525a0 | bibcode = 1994Natur.372..525F | s2cid = 1472426 }}</ref>

All human autosomes have been identified and mapped by extracting the chromosomes from a cell arrested in [[metaphase]] or [[prometaphase]] and then staining them with a type of dye (most commonly, [[Giemsa stain|Giemsa]]).<ref>{{Cite web |title=Chromosome mapping Facts, information, pictures |series=Encyclopedia.com articles about Chromosome mapping |url=http://www.encyclopedia.com/topic/Chromosome_mapping.aspx |website=encyclopedia.com |access-date=2015-12-04 |url-status=live |archive-url=https://web.archive.org/web/20151210220706/http://www.encyclopedia.com/topic/Chromosome_mapping.aspx |archive-date=2015-12-10 |df=dmy-all}}</ref> These chromosomes are typically viewed as [[karyogram]]s for easy comparison. Clinical geneticists can compare the karyogram of an individual to a reference karyogram to discover the cytogenetic basis of certain [[phenotype]]s. For example, the karyogram of someone with [[Patau syndrome|Patau Syndrome]] would show that they possess three copies of [[Chromosome 13 (human)|chromosome 13]]. Karyograms and staining techniques can only detect large-scale disruptions to chromosomes—chromosomal aberrations smaller than a few million base pairs generally cannot be seen on a karyogram.<ref>{{cite book |vauthors=Nussbaum RL, McInnes RR, Willard HF, Hamosh A, Thompson MW |year=2007 |title=Thompson & Thompson Genetics in Medicine |url=https://archive.org/details/thompsonthompson00nuss |url-access=limited |edition=7th |page=[https://archive.org/details/thompsonthompson00nuss/page/n68 69] |location=Philadelphia, PA |publisher=Saunders/Elsevier|isbn=9781416030805 }}</ref>

{| class="wikitable" style="width: 75%; margin: 1em auto 1em auto;"
|-
! colspan="2"|[[Karyotype]] of human chromosomes
|-
|align="center"|Female (XX)
|align="center"|Male (XY)
|-
|[[Image:PLoSBiol3.5.Fig7ChromosomesAluFish.jpg|420px|center]]
|[[File:Human male karyotype.gif|331px|center]]
|-
| colspan="2"|There are two copies of each '''autosome''' (chromosomes 1–22) in both females and males. The '''sex chromosomes''' are different: There are two copies of the X-chromosome in females, but males have a single X-chromosome and a Y-chromosome.
|}