Chromosome 22 trisomy syndrome. Trisomy 22. Duplication 22.
Incidence
Very rare syndrome. Sporadic. Some cases are familial.
Clinical Characteristics
The presence of an additional (third) chromosome in an otherwise diploid chromosome 22. The syndrome is relatively rare in liveborn infants and is characterized by variable abnormalities including microcephaly, epicanthal folds, micrognathia, low-set malformed ears, preauricular pits, short webbed neck, congenital heart defect, hypoplastic nails, and clinodactyly. Advanced parental age was reported in some cases. Mosaic trisomy is marked by failure to thrive, mental retardation, blepharoptosis, dental anomaly, hearing loss, low posterior hairline, ovarian failure, syndactyly, hemiatrophy, and streaked pigmentation. Complete trisomy is associated with prematurity, early death, hypertelorism, flat nasal bridge, cleft palate, renal anomaly, anorectal deformities, and abnormal external genitalia. In older literature, chromosome 22 was sometimes identified with the Down syndrome, which now is known as chromosome 21 trisomy.
Precipitants
None
Provocation Tests
None
Diagnostic Procedures
Karyotype. There is additional (third) chromosome in an otherwise diploid chromosome 22. It can be complete or mosaic.