Familial chronic lymphocytic leukemia in two siblings with ATM/13q14 deletion and a similar pattern of clonal evolution

Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in Western countries and accounts for 34% of adult leukemias in the United States1. Although the etiology of CLL remains unknown, there is increasing evidence for the pathogenetic role of inherited factors.2 The familial subtype of the disease is distinguished from sporadic CLL by the presence of at least one affected relative, with the same or a different chronic lymphoproliferation. According to the usual approach, these families have been analyzed to detect linkage, based on the hypothesis of coinheritance of genetic markers. However, due to the small pedigree sizes, these studies have proved inconclusive in determining any specific gene or non-coding region related to the pathophysiology of CLL.3, 4 Moreover, several reports on such cases reveal a significant biologic heterogeneity of familial CLL and indicate that there is no consistent pattern of pathogenesis that would suggest a simple mode of transmission. In this report, we present two siblings diagnosed with CLL, with common chromosomal aberrations and an almost identical pattern of clonal evolution, which is unusual among all published familial cases.