This resource is authored by Katy Phelan, PhD., et al

Ring chromosome 22 is a rare genetic condition resulting when one chromosome 22 forms a circular, or ring, structure (sometimes called Ring 22). The ring forms after loss (deletion) of genetic material from both the short arm and long arm of chromosome 22. The size of the deletion is variable, ranging from less than 100kb to greater than 10Mb. The clinical features are also variable but typically include developmental delay, poor muscle tone (hypotonia), severe speech delay, and minor physical features such as large ears and bulbous nose.

The ring chromosome typically occurs de novo, meaning that it is a new event in the child. Chromosome studies and genetic counseling are indicated for parents of a child with a ring chromosome to determine if the ring was inherited and to provide important information about what the ring will mean for the development and medical care of their child. A critical consideration for individuals with ring 22 is the risk of developing neurofibromatosis type 2 (NF2), as discussed in the “Signs and Symptoms” and “Related Disorders”.