Martineau M, Clark R, Farrell D M, Hawkins J M, Moorman A V, Secker-Walker L M
Haematology Department, Royal Free Hospital School of Medicine, London, United Kingdom.
Genes Chromosomes Cancer. 1996 Sep;17(1):21-30. doi: 10.1002/(SICI)1098-2264(199609)17:1<21::AID-GCC4>3.0.CO;2-4.
The incidence, type, and clonality of isochromosomes at diagnosis were investigated in acute lymphoblastic leukaemia (ALL). An isochromosome was detected in 50/1,035 (4.8%) of successfully karyotyped patients, 41/919 children (4.5%) and 9/116 adults (7.8%), who were diagnosed within a 5 year period. Isochromosomes of 21q with breakpoints in the short arm at p11 or in the long arm at q10 or q22 were identified in 15 patients (1.4%) associated with B-lineage immunophenotype, a white blood cell count (WBC) of < 10 x 10(9)/litre, and pseudo- or low hyperdiploidy. Isochromosomes of 17q and 7q occurred in 13 (1.3%) and 9 (0.9%) patients, respectively, and were associated with high hyperdiploidy. Isochromosomes of 9q and 6p occurred in 6 (0.6%) and 5 (0.5%) patients, respectively, whereas i(Xp), i(lq), and i(8q) occurred in I patient each. The isochromosome occurred as the sole abnormality in 4 patients [3 with i(21q) and I with i(7q)] and in the stemline, but with other chromosomal changes, in 35 patients. It was confined to a clonally evolved sideline in II patients. Isochromosomes occurred with established abnormalities in 7 patients: with t(1;19)-i(7q)/i(9q)/i(7q) and i(9q) each in I patient; with t(4;11)-i(7q)/i(17q) in 1 and 2 patients, respectively; and with t(9;22)-i(9q) in I patient. This study indicates that isochromosome formation can be an early chromosomal change and suggests that i(21q) occurs more frequently at diagnosis than has been previously suspected.
在急性淋巴细胞白血病（ALL）中，对诊断时等臂染色体的发生率、类型和克隆性进行了研究。在5年期间确诊的1035例成功进行核型分析的患者中，有50例（4.8%）检测到等臂染色体，其中41例（4.5%）为儿童（共919例），9例（7.8%）为成人（共116例）。15例患者（1.4%）中鉴定出21号染色体等臂体，其断点位于短臂的p11或长臂的q10或q22，这些患者具有B系免疫表型、白细胞计数（WBC）<10×10⁹/L以及假二倍体或低超二倍体。17号染色体等臂体和7号染色体等臂体分别出现在13例（1.3%）和9例（0.9%）患者中，与高超二倍体相关。9号染色体等臂体和6号染色体等臂体分别出现在6例（0.6%）和5例（0.5%）患者中，而i(Xp)、i(1q)和i(8q)各出现在1例患者中。等臂染色体作为唯一异常出现在4例患者中[3例为i(21q)，1例为i(7q)]，在35例患者中位于主干系，但伴有其他染色体改变。在11例患者中局限于克隆进化的旁系。等臂染色体与已确定的异常同时出现在7例患者中：分别有1例患者同时出现t(1;19)-i(7q)/i(9q)/i(7q)和i(9q)；分别有1例和2例患者同时出现t(4;11)-i(7q)/i(17q)；有1例患者同时出现t(9;22)-i(9q)。本研究表明等臂染色体形成可能是一种早期染色体改变，并提示i(21q)在诊断时的出现频率比先前怀疑的更高。
