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

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.