Linkage analysis for ATM in familial B cell chronic lymphocytic leukaemia

B cell chronic lymphocytic leukaemia (CLL) shows evidence of familial aggre gation, but the inherited basis is poorly understood. Mutations in the ATM gene have been demonstrated in CLL. This, coupled with a possibly increased risk of leukaemia in relatives of patients with Ataxia Telangiectasia, led us to question whether the ATM gene is involved in familial cases of CLL. To examine this proposition we typed five markers on chromosome 11q in 24 C LL families. No evidence for linkage between CLL and ATM in the 24 families studied and the best estimates of the proportion of sibling pairs that sha re no, one or both haplotypes at ATM were not different from their null exp ectations. This would imply that ATM is unlikely to make a significant cont ribution to the three-fold increase in risk of CLL seen in relatives of pat ients.