ABNORMALITIES OF THE SHORT ARM OF CHROMOSOME-12 IN T-CELL PROLYMPHOCYTIC LEUKEMIA

Abnormalities of the short arm of chromosome 12 are nonrandom events i n T cell prolymphocytic leukemia (T-PLL). Fluorescence in situ hybridi zation (FISH) studies were performed in three patients with T-PLL and one patient with T cell peripheral lymphoma and rearrangement of 12p. Whereas the rearrangements of 12p were different in the four patients, a breakpoint centromeric to the ETV6 gene was present in the three T- PLL patients. In addition, loss of heterozygosity for a chromosomal se gment telomeric to ETV6 with loss of the RAD52 locus was also shown by FISH studies. In contrast, the breakpoint was telomeric to ETV6 in th e patient with peripheral lymphoma.