Mühlematter D, Castagné C, Bruzzese O, Clément F, Schmidt P M, Bellomo M J
Division Autonome de Génétique Médicale, Centre Hospitalier Universitaire Vaudois CHUV, Lausanne, Switzerland.
Cancer Genet Cytogenet. 1996 Jul 1;89(1):44-8. doi: 10.1016/0165-4608(95)00343-6.
Tetrasomy 8 constitutes a relatively rare recurring chromosome defect in myeloid disorders. The patient reported here, a 71-year-old man, presented with tetrasomy 8 as the sole chromosome abnormality associated with an acute nonlymphocytic leukemia of the M2 type. He failed to respond to chemotherapy and died one year after diagnosis. Following conventional cytogenetics and fluorescence in situ hybridization (FISH) with a centromeric probe specific for chromosome 8, tetrasomy 8 was detected in 61% of the metaphases analyzed and trisomy 8 in 39%. FISH analysis of interphase nuclei confirmed the existence of tetrasomic (35%) and trisomic cells (56%) and revealed a number of cells with two chromosomes 8 (8%). This normal population may represent lymphocytes or myeloid cells that escaped conventional analysis due to their inability to divide or to the small number of metaphases available. The relatively higher proportion of tetrasomic cells in metaphase compared with interphase may be attributed to a proliferative advantage of tetrasomic cells in vitro or to the longer duration of their cell cycle. The simultaneous presence of trisomic and tetrasomic cells confirms the hypothesis of a clonal relationship between trisomy 8 and tetrasomy 8. Our case brings further evidence to the specificity of tetrasomy 8 to myeloid disorders and to the association of this chromosome abnormality with a relatively poor prognosis. However, new patients must be studied to further delineate this cytogenetic entity.
8号染色体四体性是髓系疾病中一种相对罕见的复发性染色体缺陷。本文报道的患者为一名71岁男性，其8号染色体四体性是与M2型急性非淋巴细胞白血病相关的唯一染色体异常。他对化疗无反应，诊断后一年死亡。采用常规细胞遗传学方法以及使用针对8号染色体的着丝粒探针进行荧光原位杂交（FISH）分析，在分析的中期相中，61%检测到8号染色体四体性，39%检测到8号染色体三体性。间期核的FISH分析证实了四体细胞（35%）和三体细胞（56%）的存在，并发现一些细胞有两条8号染色体（8%）。这个正常细胞群体可能代表由于无法分裂或中期相数量少而未被常规分析检测到的淋巴细胞或髓系细胞。与间期相比，中期相中四体细胞比例相对较高，这可能归因于四体细胞在体外的增殖优势或其细胞周期持续时间较长。三体细胞和四体细胞同时存在证实了8号染色体三体性和8号染色体四体性之间存在克隆关系的假设。我们的病例进一步证明了8号染色体四体性对髓系疾病的特异性以及这种染色体异常与相对较差预后的关联。然而，必须对新患者进行研究以进一步明确这种细胞遗传学实体。
