Trisomy 22
| Classification according to ICD-10 | |
|---|---|
| Q92.0 | Complete trisomy, meiotic nondisjunction |
| Q92.1 | Complete trisomy, mosaic (mitotic nondisjunction) |
| Q92.2 | Partial trisomy, major form
A whole arm or more doubled |
| Q92.3 | Partial trisomy, minor form
Less than a whole arm doubled |
| Q92.4 | Chromosome duplications that are only visible in the prometa phase |
| Q92.5 | Chromosome duplications, with other complex rearrangements |
| ICD-10 online (WHO version 2019) | |
A trisomy 22 is a disability caused by a tripling ( trisomy ) of genetic material of chromosome 22 based on a genome mutation .
In people with trisomy 22, chromosome 22 or part of it is present three times (= trisome) instead of usually two times (= disome) in all or in part of the body cells. The following types are distinguished:
- Free trisomy 22 : Type in which chromosome 22 is completely trisome in all body cells . The karyotype of free trisomy 22 is: 47, XX + 22 or 47, XY + 22.
- Translocation trisomy 22 : Type in which chromosome 22 is completely trisome in all body cells, but one of chromosomes 22 has attached to another chromosome. A chromosome shift is called a translocation in genetics .
- Mosaic trisomy 22 : Type in which chromosome 22 is not present in triplicate (trisome) in all body cells, but at the same time a cell line with the usual disomic set of chromosomes exists. The presence of several karyotypes within an organism is called a mosaic in genetics . Most living children with trisomy 22 have the mosaic shape, since the characteristics of the syndrome are less pronounced depending on the proportion of disome cells and, among other things. a. less serious organic malformations result in a favorable prognosis and life expectancy. The karyotype of the mosaic trisomy 22 is: 46, XX / 47, XX + 22 and 46, XY / 47, XY + 22, respectively.
- Partial trisomy 22 : Type in which chromosomes 22 are present twice (disome) in all body cells, as usual, but part ( part ) of one of the two chromosomes 22 is doubled , which means that one of chromosomes 22 is slightly longer than the other. The hereditary information of this section is therefore available three times (trisom).
Live-born children with trisomy 22 have impairments of various types and severity, depending on the type of disease. Most of them have cognitive and physical disabilities. About half of all children with partial trisomy 22 have a heart defect .
The external appearance is characterized by an unusually wide skull with a high forehead, flat face, beak-shaped nose, low-set ears, a comparatively large eye relief ( hypertelorism ) and a protruding lower jaw.
For other syndromes triggered by trisomy see there.
