Tetrasomy
title: "Tetrasomy" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["cytogenetics", "chromosomal-abnormalities"] topic_path: "science/biology" source: "https://en.wikipedia.org/wiki/Tetrasomy" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::data[format=table title="Infobox medical condition (new)"]
| Field | Value |
|---|---|
| name | Tetrasomy |
| field | Medical genetics |
| duration | Lifelong |
| :: |
| 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
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