{{other uses|Tetrasomy (disambiguation)}} {{Infobox medical condition (new) | name = Tetrasomy | synonyms = | image = | caption = | pronounce = | field = Medical genetics | symptoms = | complications = | onset = | duration = Lifelong | types = | causes = | risks = | diagnosis = | differential = | prevention = | treatment = | medication = | prognosis = | frequency = | deaths = }} A '''tetrasomy''' is a form of aneuploidy with the presence of four copies, instead of the normal two, of a particular chromosome.
==Causes== ===Full=== Full tetrasomy of an individual occurs due to non-disjunction when the cells are dividing (meiosis I or II) to form egg and sperm cells (gametogenesis). This can result in extra chromosomes in a sperm or egg cell. After fertilization, the resulting fetus has 48 chromosomes instead of the typical 46.
===Autosomal tetrasomies===
* Cat eye syndrome where partial tetrasomy of chromosome 22 is present * Pallister-Killian syndrome (tetrasomy 12p) * Tetrasomy 9p * Tetrasomy 18p * Tetrasomy 21, a rare form of Down syndrome
===Sex-chromosome tetrasomies===
* Tetrasomy X * XXYY syndrome * XXXY syndrome
== External links == {{Medical resources | DiseasesDB = | ICD10 = {{ICD10|Q|97||q|97}} - {{ICD10|Q|98||q|98}} | ICD9 = | ICDO = | OMIM = | MedlinePlus = | eMedicineSubj = | eMedicineTopic = | MeshID = D000782 | Orphanet=3305 }} {{Chromosomal abnormalities}}
Category:Cytogenetics Category:Chromosomal abnormalities