Tetrasomy
| Tetrasomy | |
|---|---|
| Specialty | Medical genetics |
Atetrasomyis a form ofaneuploidywith the presence of four copies, instead of the normal two, of a particularchromosome.
Causes
[edit]Full
[edit]Full tetrasomy of an individual occurs due tonon-disjunctionwhen thecells are dividing(meiosisI or II) to form egg and sperm cells (gametogenesis). This can result in extrachromosomesin a sperm or egg cell. After fertilization, the resulting fetus has 48chromosomesinstead of the typical 46.
Autosomal tetrasomies
[edit]- Cat eye syndromewhere partial tetrasomy of chromosome 22 is present
- Pallister-Killian syndrome(tetrasomy 12p)
- Tetrasomy 9p
- Tetrasomy 18p
- Tetrasomy 21,a rare form ofDown syndrome