Trisomy 16
| Classification according to ICD-10 | |
|---|---|
| Q92.- | Other trisomies and partial trisomies of the autosomes Excl. : Trisomy 13, 18, 21 |
| 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 |
| Chromosome duplications, with other complex rearrangements | |
| ICD-10 online (WHO version 2019) | |
A trisomy 16 is a by tripling ( trisomy ) of genetic material of the 16th chromosome caused genome mutation . Most of it is fatal during pregnancy ; Trisomy 16 can be detected in an average of 32 out of 100 children with some form of trisomy who die during pregnancy due to spontaneous miscarriage . This form of trisomy is the most common chromosomal cause of spontaneous abortions.
A trisomy 16 is genetically characterized in that chromosome 16 or a part of it is present three times (= trisome ) instead of usually two times (= disome) in all or in part of the body cells. The likelihood of trisomy 16 in babies increases with the age of the child's mother.
There are four types of trisomy 16:
- Free trisomy 16 : Type in which chromosome 16 is completely trisome in all body cells . The karyotype of free trisomy 16 is: 47, XX + 16 or 47, XY + 16.
- Translocation trisomy 16 : Type in which chromosome 16 is completely trisome in all cells of the body, but one of chromosomes 16 has attached to another chromosome. A chromosome shift is called a translocation in genetics .
- Mosaic trisomy 16 : Type in which chromosome 16 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 . The karyotype of mosaic trisomy 16 is: 46, XX / 47, XX + 16 and 46, XY / 47, XY + 16, respectively.
- Partial trisomy 16 : Type in which chromosomes 16 are present twice (disome) in all body cells, as usual, but part ( part ) of one of the two chromosomes 16 is doubled , which means that one of chromosomes 16 is slightly longer than the other. The hereditary information in this section is therefore available three times (trisom).
forecast
While children with free trisomy 16 and translocation trisomy 16 are not viable, with the mosaic type and partial trisomy 16, depending on the proportion and impact of the trisome chromosome material, a longer survival is possible with adequate treatment of possibly existing organ malformations.
Symptoms
Due to the rare live birth of children with trisomy 16, mainly prenatal (prenatal) identifiable features are documented that occur more frequently in affected babies. These include: heart defects , increased neck transparency , singular umbilical artery , flexion contracture of the fingers (fingers crossed), omphalocele and slowed but symmetrical growth. After birth, a four-finger furrow can often be recognized in children who have already died . Live-born babies have generalized muscle hypotonia , which can lead to poor drinking.
Web links
- G Haverkämper, M Emeis, B Stiller, M Stumm, R Rossi: Complex heart defect in trisomy 16 mosaic . In: Z Obstetrics Neonatol . tape 209 , 2005, pp. P52 ( thieme-connect.com ).
