This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Ring chromosome 9 is a very rare chromosome abnormality in which the ends of chromosome 9 join together to form a ring shape. The resulting ring may be missing genes, or it may contain extra copies of genes. Therefore, the severity and symptoms associated with ring chromosome 9 vary from person to person. Signs and symptoms that may be present in a person with ring chromosome 9 include slow growth and short stature, learning disabilities, small head size, distinctive facial features, low muscle tone (hypotonia), skeletal abnormalities, and/or other birth defects involving various parts of the body. However, people with ring chromosome 9 can be generally healthy and have no major birth defects.
Ring chromosome 9 typically is not inherited and occurs sporadically, during the formation of egg or sperm cells or shortly after the egg and sperm join together. Occasionally, one of the parents has a chromosome abnormality involving chromosome 9. Chromosome testing of both parents can help determine whether the ring chromosome was inherited and whether future children have an increased chance to have a chromosome abnormality. Treatment for ring chromosome 9 depends on the signs and symptoms present in each person.
For more information, visit GARD.