Trisomy 3
| 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) | |
The trisomy 3 is a by three times ( trisomic ) presence of genetic material of chromosome 3 caused disability based on a genome mutation . A distinction is made between the following forms:
- 1. Free trisomy 3
- Type in which chromosome 3 is completely triple in all body cells .
- 2. Translocation trisomy 3
- Type in which chromosome 3 is threefold in all body cells. However, one or part of the three chromosomes has attached to another chromosome. This "change of location" of a chromosome or a piece of chromosome is known as a translocation in genetics .
- 3. Mosaic trisomy 3
- Type in which chromosome 3 is not triple in all body cells, but at the same time a cell line with the usual diploid set of chromosomes can be found. In genetics, a mosaic is understood to mean the presence of several karyotypes within an organism.
- 4. Partial trisomy 3
- Type in which a chromosome section of the distal section of the long arm of one of the two chromosomes 3 is tripled. The chromosomes come though as usual twice in all body cells, but a part (is part ) tripled one of the two chromosomes 3, whereby one of the chromosomes is slightly longer than the other. The hereditary information in this section is therefore available three times.
Symptoms
Children with free trisomy 3 are not viable and usually die during pregnancy . Children with partial trisomy 3 and mosaic trisomy 3 can definitely be viable, although life expectancy depends on the type and severity of, in particular, organic malformations and their treatment. In children with a form of trisomy 3 who are born alive, different peculiarities can be determined which occur depending on the chromosome segment present in the trisome. The following special features in children with partial trisomy 3p or mosaic trisomy 3 have been described in different case studies:
- Comparatively little amniotic fluid prenatally ( oligohydramnios ) and dystrophy (insufficient supply of nutrients )
- Delayed development, failure to thrive (even before birth), hypotonia
- Malformation of the brain, associated with cognitive disabilities and sometimes epilepsy
- Brachycephaly , microcephaly with a triangular skull shape ( trigonocephaly ) and a short neck
- Cleft lip and palate , high palate
- Hypertelorism , upward sloping (laterally-cranially rising) eyelid axes , full eyelids , unusually long eyelashes , bushy eyebrows that have often grown together ( Synophrys )
- small, short nose with specially shaped nostrils and a broad nasal bridge
- specially shaped, comparatively small ears
- corners of the mouth pointing downwards, small chin
- pronounced, long philtrum between upper lip and nose
- comparatively far apart nipples
- excessive hair growth on the body ( hirsutism , hypertrichosis ), unusually low hairline over the forehead and on the back of the neck
- Clinodactyly , brachydactyly , camptodactyly , underdeveloped (hypoplastic) nails
- Malformation of the eyes (including unusually small eyeballs, glaucoma , coloboma / gap formation due to incomplete closure of the embryonic eye cup fold)
- Malformations of the limbs: short stature, short fingers, sometimes syndactylia of the toes, polydactyly of the fingers (duplication of the thumbs )
- Heart defects , rib and vertebral abnormalities, kidney malformations
- in girls: malformation of the uterus , connective tissue ovaries
- in boys: rather small penis, hypospadias , undescended testicles
