Two Cases of Translocation t(3;6)(p14;p22): A Non Random Chromosomal Abnormality?

It is generally accepted that the short arm of chromosome 6 is a likely site to be involved in chromosomal rearrangements of MDS/ANLL following radio/chemotherapy. We report here two cases of t(3;6)(p14;p22). One patient is a 55 years old male with a previous history of occupational exposure who developed, an acute megakaryoblastic leukemia after a preleukemic phase. Chromosome analysis showed a t(3;6)(p14;p22), associated with del (5)(q14q31), -7, with variations and a trend to hypoploidy. The second patient is a 33 years old man, with chronic myeloid leukemia treated with Hydroxyurea (HU), HU + $aL-IFN and $aL-IFN alone. The first cytogenetic study before treatment, showed a t(9;22)(q34;q11). In the following months the patient had simultaneously t(9;22)(q34;q11) + t(3;6)(p14;p22) in a minority and thereafter in all the mitoses, with progressive deterioration, megakaryocyte abnormalities, but no blast crisis. Our patients are compared with the only 5 other published cases with t(3;6)(p14;p22), who shared some common features, namely a past history of chemo/radiotherapy or exposure to chemical mutagens and an association with other, so-called "secondary" chromosome aberrations, on segments 3p, 5q, 7q, 12p and 17p. We suggest that this uncommon translocation t(3;6) is nonrandom. It is worth noting that band 6p21 is the site of pim 1 oncogen, and that a fragile site is located on band 3p14.