Submicroscopic deletions at 7q region are associated with recurrent chromosome abnormalities in acute leukemia.

Loss of heterozygosity (LOH) on the long arm of chromosome 7 (7q) has been frequently reported in several types of human cancer including hematologic malignancies. Moreover, monosomy of chromosome 7 and 7q deletions have been associated in acute myeloid leukemia (AML) with aggressive disease and poor prognosis.Using a panel of 11 polymorphic microsatellite markers at bands 7q21-q36, we investigated fifty patients (acute myeloid leukemia [AML], n=33 and acute lymphoid leukemia [ALL], n=17) for LOH, a hallmark of possible involvement of tumor suppressor genes. In parallel, the same acute leukemia (AL) cases were studied by conventional cytogenetics.A total of 48 spots of allelic loss were observed in 16 (32%) out of 50 patients (AML, n=11 and ALL, n=5). Among LOH+ve cases 3 showed chromosome 7 monosomies, whereas no cytogenetically detectable abnormalities were observed in chromosome 7 in the remaining 13.Comparison with karyotypic results indicated that presence of LOH at 7q21-q36 was significantly associated with other chromosomal aberrations. In fact, an altered karyotype was detectable in 87% of LOH+ve and in 52% of LOH(-ve) AL cases (p=0.024). In addition, LOH at 7q was prevalently associated with unfavorable cytogenetic lesions (p=0.013). Our study represents the first report of a significant association between LOH and recurrent chromosomal abnormalities in AL patients suggesting that the 7q21-q36, region may be an unstable area prone to chromosome breakage in patients with an abnormal karyotype.