Mosaic trisomy 22
is a chromosome disorder in which chromosome 22 is present three times, instead of the usual two times, in some cells of the body. The range and severity of the disorder can vary widely. Some of the features that have been associated with this condition include growth delays, cognitive deficiencies, unequal development of the two sides of the body (hemidystrophy), webbing of the neck, abnormal deviation of the elbows when extended (cubitus valgus), multiple pigmented moles or birthmarks, distinctive malformations of the head and face, and other physical abnormalities. A number of cases of children with mosaic trisomy 22 and normal growth and development have also been described. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.