Oner G, Jauch A, Eggermann T, Hardwick R, Kirsch S, Schiebel K, Rappold G, Robson L, Smith A
Cytogenetics Department, Royal Alexandra Hospital for Children, Westmead, Australia.
Am J Med Genet. 2000 May 15;92(2):101-6.
Structural abnormalities of chromosome 18p mainly consist of isochromosomes of the short arm, which result in tetrasomy 18p. Trisomy 18p is much rarer, and less well characterized. We report on a 12-year-old girl with minor facial anomalies, delayed development, abnormal hands, atopic dermatitis, and hearing loss. She was mosaic for two abnormal cell lines in peripheral blood. In 90% of cells, a dicentric chromosome with duplication of the whole short arm of chromosome 18 resulted in trisomy 18p; 10% of cells had monosomy 18p, arising from a t(14;18)(p11;q11). FISH mapping, with multiple region specific and locus specific probes from the short and long arm of chromosome 18, showed that the structure of the dicentric chromosome 18 was 18pter-->18q23::18q11-->18pter. DNA polymorphisms for chromosome 18 showed that the abnormalities of chromosome 18 were paternal in origin. Combining all results, we could link the trisomy 18p and monosomy 18p to a common origin via a complex series of events in an early mitosis.
18号染色体短臂的结构异常主要由短臂等臂染色体组成，导致18号染色体短臂四体。18号染色体短臂三体则更为罕见，且特征描述较少。我们报告了一名12岁女孩，她有轻微面部异常、发育迟缓、手部异常、特应性皮炎和听力损失。她外周血中存在两种异常细胞系的嵌合体。在90%的细胞中，一条具有18号染色体整个短臂重复的双着丝粒染色体导致了18号染色体短臂三体；10%的细胞具有18号染色体短臂单体，源于t(14;18)(p11;q11)。使用来自18号染色体短臂和长臂的多个区域特异性和位点特异性探针进行荧光原位杂交图谱分析显示，双着丝粒18号染色体的结构为18pter→18q23::18q11→18pter。18号染色体的DNA多态性表明，18号染色体的异常源自父方。综合所有结果，我们可以通过早期有丝分裂中一系列复杂事件将18号染色体短臂三体和18号染色体短臂单体联系到一个共同起源。
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