Viguié F, Prigent Y, Ramond S, Baumelou E, Cadiou M, Dreyfus F, Zittoun R
Laboratoire de Biologie de la Fertilité et de Cytogénétique, Hôpital Hotel-Dieu, Paris, France.
Leukemia. 1995 Jul;9(7):1154-8.
Monosomy 7 was detected in bone marrow cells from three patients, one with myeloid leukemia, and two others with myelodysplastic syndrome following previous chemotherapy. Fluorescence in situ hybridization (FISH), carried out with an alphoid DNA probe specific for chromosome 7 centromere, showed that a small marker chromosome present in the tumor cells' karyotype of the three patients, was derived from the missing chromosome 7. In two cases, the marker was a ring chromosome, whereas in the third case it was a tiny dot-like chromosome, unnoticed at first examination on R-banded metaphases. In the three cases, the marker was lost in a proportion of tumor cells. FISH experiments suggested that the marker centromere had undergone structural alterations, with a fluorescence pattern distinct from a normal one. On the whole, these data suggest that: firstly, leukemia-associated monosomy 7 results, in a proportion of cases, from a structural event rather than from simple loss of a whole chromosome 7; secondly, interpretation of interphase FISH must be cautious in monosomy 7 evaluation; and thirdly structural alteration of the chromosome 7 derivative alphoid DNA could explain its propensity to segregate unequally and to be lost at mitosis.
在三名患者的骨髓细胞中检测到7号染色体单体，其中一名患有髓系白血病，另外两名在先前化疗后患有骨髓增生异常综合征。用针对7号染色体着丝粒的α卫星DNA探针进行荧光原位杂交（FISH），结果显示这三名患者肿瘤细胞核型中存在的一条小标记染色体源自缺失的7号染色体。在两例中，标记为环状染色体，而在第三例中它是一个微小的点状染色体，在最初对R带中期进行检查时未被注意到。在这三例中，标记在一部分肿瘤细胞中丢失。FISH实验表明标记着丝粒发生了结构改变，其荧光模式与正常模式不同。总体而言，这些数据表明：首先，在一部分病例中，与白血病相关的7号染色体单体是由结构事件导致的，而非简单地整条7号染色体丢失；其次，在7号染色体单体评估中，对间期FISH的解读必须谨慎；第三，7号染色体衍生的α卫星DNA的结构改变可以解释其在有丝分裂时倾向于不均等分离并丢失的现象。
