A family survey was conducted among 909 patients with leukaemia of all types, with the purpose of establishing the incidence of further cases of leukaemia among relatives. Among a total of 41,807 relatives 8,349 were deceased, and the cause of death was objectively confirmed in 5,011. 72 patients had one or more relatives with leukaemia. First degree relatives with leukaemia were much more frequent in families of patients with chronic lymphocytic than in those! of patients with chronic granulocytic leukaemia. The incidence of leukaemia among first degree relatives was established to be 2.8-3.0 times, among more distant relatives about 2.3 times, and overall about 2.5 times that expected. This excess is of the order of that observed in relatives of patients with certain solid tumors. Genetic factors may have accounted for much of the excess incidence in chronic lymphocytic and acute leukaemia, but there was little evidence for a genetic background in chronic granulocytic leukaemia. With the possible exception of one family with muitiple cases, a simple Mendelian mechanism did not appear to be involved in the leukaemia families investigated. It appeared more likely that a polygenic mechanism led to a heightened susceptibility to the disease in these families.

No abstract

707 conl)lying with the above definition, with the exception of a Ilumber in which tiit' thrombocythemia appeared to be a mere transient i ase in tile course of otiler well substantiated (liSeaSeS. A history of hemorrhage was essential for inclusioii. Either thrombocytosis or thrombosis without hemorrhage VdS illsufficient; for example, cases 1 and 2 reported by Fanger et al.'1' were included, while case 3 was excluded because the patient had not i)led. A diagnosis of "essential" or "idiopathic" thrombocythemia was not acceptable for inclusion, unless hemorrhage was also reported. Cases excluded for this reason comprise tilose of Arlotti and et al.54 (case 3) ,N' 1ortensen, Reid,#{176}'Revol#{176} (cases 1 and 2) ,Rowl ands and Vaizey"4 (case 2) ,Schi ipbach and I-lerrmann#{176}

No abstract

Thirteen cases of leukemia, 12 of them acute, occurred in 3 generations of a family comprising 293 members. Individual cases could not be linked to the possession of any of a range of genetic markers. Cytogenetic studies showed no constitutional chromosome abnormalities. Preliminary results of virologic studies suggested the presence of oncornaviruses in at least 1 leukemic individual in this family. This aggregation of leukemia cases likely resulted from a genetic, probably polygenic, predisposition, in association with the activity of leukemogenic factors whose nature remains to be clearly defined.