1532例拟行辅助生殖技术夫妇细胞遗传学分析

目的对准备实施辅助生殖技术的夫妇行染色体检查,探讨该项检查的临床意义。方法对1532例拟行辅助生殖技术者外周血淋巴细胞行染色体常规G显带核型分析,必要时辅做高分辨G带、C带或N带。结果 1532例患者中发现染色体变异者108例(7.05%),染色体异常畸变25例(1.63%),染色体多态性变异83例(5.42%)。结论拟行辅助生殖技术夫妇实行染色体筛查是非常必要的,是提高辅助生殖技术的成功率,降低病残儿发生率的重要保障。     

A new chromosome banding technique,spectral color banding (SCAN), for full characterization of chromosomal abnormalities

We have developed spectral color banding (SCAN) as a new chromosome banding technique based on spectral analysis of differentially labeled chromosome band-specific painting probes. In this study, we succeeded in displaying a multicolor banding pattern for chromosome 3, which was almost identical to the pattern obtained with the corresponding G-banding. We applied this method to metaphase cells from different normal male donors with various levels of G-banding resolution, ranging from 250 to 850 bands per haploid set. The same multicolor banding pattern was observed in all samples regardless of the length of the chromosomes or the quality of the G-banding. We then used SCAN in a diffuse large B-cell lymphoma case for a complete analysis of the intrachromosomal change for chromosome 3, which could not be fully characterized by G-banding or even by spectral karyotyping (SKY). SCAN could detect the duplicated segment and identify the origin of the chromosome band on the basis of the specific spectral color of each band. This study demonstrates that SCAN is a useful tool for full characterization of chromosomal abnormalities not identified by SKY.     

用高分辨G带和人工细菌染色体荧光原位杂交技术分析中国儿童孤独症患者的染色体改变

目的 检测中国儿童孤独症患者的特征性染色体改变。方法 应用高分辨G带和人工细菌染色体(bacterial artificial chromosome，BAC)荧光原位杂交(flourescence in situ hybridization，FISH)分析68例中国儿童孤独症患者的染色体改变。结果 用G带分析观察到有染色体改变的4例患者，分别为1例t(4；6)(q23-24；p21)、1例21p 和2例9号染色体臂间倒位。BAC FISH进一步证实易位病例，而且更精确[t(4；6)(q25-26；p21-1)]；涉及7号、15号、2号染色体的BAC FISH均未观察到文献中报道的染色体改变；而9号染色体的臂间倒位和21p 因无BAC克隆而无法证实。结论 用G带和BAC FISH发现少数中国孤独症患者有染色体改变，但远没有文献中报道的10％～48％那么高。BAC FISH有助于精确地确定染色体易位断裂点。     

Replication Banding Patterns in Human Chromosomes Detected Using 5-ethynyl-2'-deoxyuridine Incorporation

A novel technique using the incorporation of 5-ethynyl-2''-deoxyuridine (EdU) into replicating DNA is described for the analysis of replicating banding patterns of human metaphase chromosomes. Human lymphocytes were synchronized with excess thymidine and treated with EdU during the late S phase of the cell cycle. The incorporated EdU was then detected in metaphase chromosomes using Alexa Fluor® 488 azides, through the 1,3-dipolar cycloaddition reaction of organic azides with the terminal acetylene group of EdU. Chromosomes with incorporated EdU showed a banding pattern similar to G-banding of normal human chromosomes. Imaging by atomic force microscopy (AFM) in liquid conditions showed that the structure of the chromosomes was well preserved even after EdU treatment. Comparison between fluorescence microscopy and AFM images of the same chromosome 1 indicated the presence of ridges and grooves in the chromatid arm, features that have been previously reported in relation to G-banding. These results suggest an intimate relationship between EdU-induced replication bands and G- or R-bands in human chromosomes. This technique is thus useful for analyzing the structure of chromosomes in relation to their banding patterns following DNA replication in the S phase.     

Angelman综合征的诊断及其产前诊断

目的 对临床疑似Angelman综合征(Angelman syndrom,AS)的患者进行诊断并对已确诊的患儿家庭行产前诊断.方法 用高分辨染色体和荧光原位杂交(fluorescence in situ hybridization,FISH)技术对患者进行检测.结果 诊断出两例AS患者和一名正常胎儿.结论 结合临床症状、高分辨核型分析、FISH可确诊Ⅰ型AS患者,为临床提供准确的遗传咨询和产前咨询,并可对有AS生育史的家庭行产前诊断.     

Atomic force microscopy of plant chromosomes

Atomic force microscopy has been used to image plant chromosomes from standard preparations without staining or coating. This has enabled the collection of high-resolution three-dimensional data on surface structure. The technique has been further applied to the imaging of C-banded chromosomes revealing structural changes resulting from the banding treatment. The bands were observed as localized areas of high relief.     

Isodicentric Philadelphia chromosomes in imatinib mesylate (Gleevec)-resistant patients

Amplification/duplication of the BCR-ABL gene has been found to be one of the key factors leading to drug resistance to imatinib mesylate (IM). In the present study, we used G-banding to identify the presence of de novo identical isodicentric chromosomes in IM-resistant patients. Fluorescence in situ hybridization (FISH) analysis on interphase nuclei confirmed the heterogeneity and amplification of the fused BCR-ABL gene. FISH analysis superimposed on G-banding confirmed the presence of isodicentric Philadelphia chromosomes. The impact of the isodicentric Philadelphia chromosomes on genomic instability, heterogeneity, and amplification of the Philadelphia chromosomes in IM-resistant patients is discussed.     

Three-dimensional structure of G-banded human metaphase chromosomes observed by atomic force microscopy

The structure of G-bands in human metaphase chromosomes was analyzed by comparison between light microscopic and atomic force microscopic (AFM) images of the same chromosomes. G-bands of the chromosomes were made by trypsin treatment followed by staining with a Giemsa solution. The banded chromosomes examined by light microscopy were dried either in air or in a critical point-drier, and observed by non-contact mode AFM. Air-dried chromosomes after G-band staining showed alternating ridges and grooves on their surface, which corresponded to light-microscopically determined G-positive and G-negative bands, respectively. At high magnification, the G-positive ridges were composed of densely packed chromatin fibers, while the fibers were loose in the G-negative grooves. Fibers bridging the gap between sister chromatids of a mitotic pair were often found, especially in the G-positive portions. These findings suggest that the G-banding pattern reflects the high-order structure of human metaphase chromosomes.