Onodera N, McCabe N R, Nachman J B, Johnson F L, Le Beau M M, Rowley J D, Rubin C M
Department of Pediatrics, University of Chicago, Illinois 60637.
Genes Chromosomes Cancer. 1992 Jun;4(4):331-6. doi: 10.1002/gcc.2870040410.
Acute lymphoblastic leukemia (ALL) of childhood is frequently characterized by a hyperdiploid karyotype. Typically, most of the affected chromosomes in the abnormal clone are present in three copies. We have studied two patients with hyperdiploid ALL whose leukemic cells were atypical in that all or most of the chromosomes were present in either two or four copies, raising a suspicion that the observed karyotype arose through duplication of chromosomes in a precursor cell with a near-haploid chromosome number. Analysis of restriction fragment length polymorphisms confirmed that both cases arose from a near-haploid cell; all informative disomic chromosomes tested had loss of heterozygosity. Furthermore, the hyperdiploid karyotypes did not arise via a perfect haploid cell with exactly 23 chromosomes, because tetrasomic chromosomes remained heterozygous. These two patients probably are classified best as near-haploid cases, which often are observed to have a co-existing hyperdiploid clone with a duplicated chromosome set. The distinction between typical hyperdiploidy and hyperdiploidy arising via a near-haploid cell may be clinically important, because the prognosis for patients with a hyperdiploid karyotype is favorable in comparison to that of patients with a near-haploid karyotype.
儿童急性淋巴细胞白血病（ALL）常表现为超二倍体核型。通常，异常克隆中大多数受累染色体以三个拷贝存在。我们研究了两名超二倍体ALL患者，其白血病细胞具有非典型性，即所有或大多数染色体以两个或四个拷贝存在，这引发了一种怀疑，即观察到的核型是通过具有近单倍体染色体数目的前体细胞中染色体的复制产生的。对限制性片段长度多态性的分析证实，这两个病例均起源于近单倍体细胞；所有检测的信息性二体染色体均出现杂合性缺失。此外，超二倍体核型并非通过恰好具有23条染色体的完美单倍体细胞产生，因为四体染色体仍为杂合状态。这两名患者可能最好归类为近单倍体病例，这类病例常观察到存在一个具有重复染色体组的共存超二倍体克隆。典型超二倍体与通过近单倍体细胞产生的超二倍体之间的区别可能具有临床重要性，因为与近单倍体核型患者相比，超二倍体核型患者的预后较好。
