Third Case of Chronic Lymphocytic Leukaemia in a Carrier of the Inherited Ch1 Chromosome

Abstract
Chronic lymphocytic leukaemia has developed in three siblings who are all carriers of the abnormal Ch1 chromosome. 3H-thymidine autoradiography showed Ch1 to be a G2 autosome, from which the short arm is absent, and not G1, which is trisomic in Down's syndrome and which is believed to form the abnormal Ph1 chromosome. Ch1 is not of general significance in the aetiology of chronic lymphocytic leukaemia, but it must be considered as a possible predisposing factor to leukaemia in the present family.