Also found in: Acronyms.
an obsolete term describing an abnormal small acrocentric chromosome (no. 21 or 22) with complete or almost complete deletion of the short arm; found in cultured leukocytes in some cases of chronic lymphocytic leukemia, also in some unaffected relatives of patients.
Christchurch chromosome (Ch1)
Etymology: Christchurch, city in New Zealand
an abnormally small, acrocentric chromosome (either chromosome 21 or chromosome 22), in which the short arm is missing or partially deleted. The aberration is associated with chronic lymphocytic leukemia but has also been found in patients with various other defects. See also Philadelphia chromosome.