Complete Trisomy 22
Complete trisomy 22 occurs when an extra (third) copy of chromosome 22 is present in every cell of the body, where there should normally only be two copies. A normal human karyotype will read 46, XX for female, or 46, XY for male, however, people with complete (or full) trisomy 22 will have a karyotype that reads 47, XX or XY +22.
Reported liveborn cases of complete (or full) trisomy 22 are very rare, but the trisomy itself is not so rare, being found in 2-5% of miscarriages, second only to trisomy 16. Affected individuals have a shortened life span and it is rare to find many articles in the literature highlighting living cases with this condition. Most reported cases which survive to term, live less than three years, with more than half of all babies born with this diagnosis living less than a week. This is based only on published reports.
Early reports of full trisomy 22 which discuss extended survival rates are thought to represent cases of unbalanced translocation 11/22 (Emanuel Syndrome) or mosaic trisomy 22. Our group is aware of a few reports of people with full trisomy 22 living longer than can be identified in medical journals.
There has been a shift in offering surgical intervention for children born with this condition, offering opportunities for extended survival rates (Phung, et al 2023). Due to the limited information on trisomy 22, it may be helpful for parents to look to the work of SOFT – Support Organization for Trisomy, and children born with trisomies 13 and 18. A statement by the SOFT Board of Directors released December 14th, 2023 discusses terminology used to describe these trisomies.
CLINICAL FEATURES MAY INCLUDE:
- brain abnormalities (such as microcephaly, hydrocephalus and others)
- ear differences
- webbed neck
- cardiac abnormalities
- lung abnormalities
- kidney problems (missing, extra, or underdeveloped kidneys)
- growth retardation
- cleft palate/lip
- small jaw (micrognathia)
- diaphragmatic hernias
- flat nasal bridge
- skin differences (pits, tags, excess neck skin)
- hypospadias
- anal stenosis/atresia
- differences in genitalia
- limb and finger/toe differences (clubbed feet, webbing of fingers/toes)
- cyanosis
- preauricular pits/tags
- preauricular sinus
- imperforate anus/rectal abnormalities
- eye differences (colobomas, strabismus, others)
- vascular malformations
- gastrointestinal malformations
- seizures
- hypotonia (weak muscle tone)
- significant developmental delays
There is a related condition called mosaic trisomy 22. This is where people have an extra chromosome 22 in only some cells of their body. This impacts them less than full trisomy 22 and their outcome can be less severe. (See Mosaic Trisomy 22)
Families can benefit from joining C22C’s Facebook Group to connect with others.
Search PUBMED for articles on Trisomy 22