Modi Deepak, Berde Prajakta, Bhartiya Deepa
Cell Biology Department, Research Society, Bai Jerba Wadia Hospital for Children, Acharya Donde Marg, Parel, Mumbai 400 012, India.
Reprod Biomed Online. 2003 Jun;6(4):499-503. doi: 10.1016/s1472-6483(10)62174-8.
Recent data suggest that chromosome mosaicism is a possible mechanism for intrauterine and postnatal survival in cases of trisomy 18 and Turner syndrome (45X). The aim of this study was to evaluate if chromosomal mosaicism is a possible mechanism of survival in Down syndrome (DS) (trisomy 21) individuals. Mosaicism was studied by interphase fluorescence in-situ hybridization (FISH), using a specific probe for chromosome 21 (21q22.13-21q22.2) in 78 cases suspected of DS. To rule out tissue specific mosaicism, buccal cells or amniocytes were analysed in addition to blood in 20 DS cases. Thirty-three per cent of the cases studied by FISH in only peripheral blood were mosaics. In 20 cases of trisomy 21, two tissues were studied and mosaicism was not detected in either of the two tissues in 15 cases. The remaining five cases were mosaics in both the tissues analysed. Clinical comparisons in 17 DS mosaics showed a direct relationship between the percentage of trisomic cells and the degree of phenotypic manifestations. These results suggest that mechanism(s) other than mosaicism may exist for the intrauterine and postnatal survival of DS cases.
近期数据表明，染色体嵌合现象可能是18三体综合征和特纳综合征（45,X）病例中宫内及出生后存活的一种机制。本研究的目的是评估染色体嵌合现象是否为唐氏综合征（DS，21三体）个体存活的一种可能机制。采用间期荧光原位杂交（FISH）技术，使用针对21号染色体（21q22.13 - 21q22.2）的特异性探针，对78例疑似DS病例进行嵌合现象研究。为排除组织特异性嵌合现象，除了对20例DS病例的血液进行分析外，还对其颊黏膜细胞或羊水细胞进行了分析。仅对外周血进行FISH研究的病例中，33%为嵌合体。在20例21三体病例中，对两种组织进行了研究，15例在两种组织中均未检测到嵌合现象。其余5例在分析的两种组织中均为嵌合体。对17例DS嵌合体进行的临床比较显示，三体细胞百分比与表型表现程度之间存在直接关系。这些结果表明，DS病例宫内及出生后存活可能存在嵌合现象以外的其他机制。
