ABSTRACT
During the past two decades, the close association between specific chro mosomal abnormalities and various hematologic neoplasms has been estab lished. The recent molecular cloning of most recurrent chromosome trans location breakpoints and the identification of the involved genes are helping to elucidate the mechanisms of leukemogenesis and aberrant regulation of leukemic cell growth. Understanding the role of the affected genes may provide insights into the altered biology of these cells and lead to better treatment ( 1 -5) . Perhaps more important, molecular diagnostic tests that are based on the sequence of chromosomal breakpoint regions are constantly being developed. In time, these new assays will augment the armamentarium that allows accurate identification of clonal rearrangements of genes and subclassification of diseases. Tables 1 and 2 present the most frequent karyotypic-morphologic and genetic changes associated with lymphoid neoplasias .
