FISH技术在一例45,X/46,X,i（Xq）Turner综合征中的研究

目的应用荧光原位杂交技术（fluorescence in situ hybridization,FISH）分析一例45,X/46,X,i（Xq）嵌合体,并探讨其形成机理,临床表型与染色体核型的关系。方法通过染色体常规G显带技术,并联合FISH技术,选用X染色体着丝粒特异DNA探针（CSPX）和X染色体长臂全涂抹探针（Xq）,进一步确认异常染色体的来源。结果 G显带分析该患者染色体核型为45,X/46,X,i（Xq）,FISH技术证实了该异常染色体为Xq等臂染色体。结论 X短臂单体长臂三体型Turner综合征患者的临床表型与其染色体核型相关;在常规G显带的基础上,应用FISH技术可准确识别异常染色体,对明确诊断及后续治疗有指导意义。     

用双色荧光原位杂交检测人精子染色体非整倍体率

目的检测人精子染色体非整倍体率。方法采用双色荧光原位杂交（ＦＩＳＨ）方法,取少量精标本经洗后制片,用二硫苏糖醇（ＤＴＴ）和二碘水杨酸锂（ＬＩＳ）处理,使精子头部染色质去凝集。然后,与生物素标记的α卫星Ｘ染色体特异ＤＮＡ探针（ＤＸＺ１）和地高辛标记的α卫星Ｙ染色体特异ＤＮＡ探针（ＤＹＺ３）进行原位杂交。用ＣＹ３－链亲和素、山羊抗链亲和素检测Ｘ染色体探针杂交信号;用鼠抗地高辛抗体、与荧光素结合的兔抗鼠抗体检测Ｙ染色体探针杂交信号。结果在Ｎｉｋｏｎ荧光显微镜下可以清楚看到精子头部的杂交信号,头部有１个红色荧光杂交信号的精子为Ｘ染色体精子（Ｘ精子）,有１个绿色荧光杂交信号的精子为Ｙ染色体精子（Ｙ精子）。精子头部有２个荧光杂交信号的精子为染色体数目异常精子。若用１条常染色体探针和１条性染色体探针进行ＦＩＳＨ,可以区别头部有２个相同颜色荧光杂交信号的精子属非整倍体精子或二倍体精子。结论双色荧光原位杂交（ＦＩＳＨ）方法,可以用于测定接触致突变剂和非整倍体诱导剂后,人精子染色体非整倍体率的变化。     

Asynchronous chromosome pairing in male meiosis of the rat (Rattus norvegicus)

Premeiotic and meiotic chromosome distribution was studied in rat testes suspensions by a triple-color fluorescent staining protocol which allows simultaneous visual inspection of two chromosomal targets highlighted by FISH together with immunostained SCP3 synaptonemal complex (SC) proteins which are marked by a third, composite color. Triple labeling with rat chromosome (RNO) 4q and 19p specific probes and SCP3 staining disclosed that homologs are separated in premeiotic and leptotene nuclei. Pairing of homologous chromosome regions commenced during early zygotene, with pairing of the small metacentric chromosomes 19 preceding that of the distal region of the long arm of RNO4. Our results show that homolog association occurs during zygotene of rat spermatogenesis, with small and large chromosomes showing a considerable asynchrony. Comparison with pairing progression in meiosis of other mammals suggests that asynchronous chromosome pairing reflects size differences within a complement. This revised version was published online in July 2006 with corrections to the Cover Date.     

Chromosome 21 abnormalities with AML1 amplification in acute lymphoblastic leukemia

Fluorescence in situ hybridization (FISH) studies were performed in three cases of acute lymphoblastic leukemia (ALL) with marker chromosomes to analyze the contribution of chromosome 21 in these markers. FISH with a chromosome 21 painting probe confirmed that chromosome 21 was involved in all three cases. FISH with YAC probes showed that the number of extra copies varied according to their location on chromosome 21. Attention was focused on the AML1 gene, which was present as five copies in most of the cells exhibiting the marker chromosomes. As controls, 11 cases of childhood ALL were studied with PAC probes covering AML1. The results agreed with the banded karyotypes in 10 patients. FISH uncovered a clone with four copies of AML1 which were only observed by FISH analysis of interphase nuclei in one patient. No point mutation was detected in exons 3-5, encoding the runt domain of AML1, in the three cases, suggesting an oncogenic role of wild-type AML1 amplification.     

RAPID DETECTION OF KARYOTYPE CHANGES IN INTERPHASE BONE MARROW CELLS BY OLIGONUCLEOTIDE PRIMED IN SITU HYBRIDIZATION (PRINS)

Fluorescence in situ hybridization (FISH) using DNA probes of several hundred or thousand base pairs in length enables the visualization of chromosomal aberrations in interphase nuclei. A new method for in situ labelling of chromosomes is the oligonucleotide primed in situ labelling (PRINS) technique. So far, this has mainly been used to demonstrate subtle changes in metaphase spreads. The aim of the present study was to investigate the suitability of PRINS for detecting chromosome gains or losses in interphase nuclei. This technique was compared with FISH analysis by examining the bone marrow cells of ten patients in whom the karyotypes were known from conventional chromosome banding. Corresponding results by both PRINS and FISH were obtained for chromosomes 1, 3, 7, 8, and Y in five patients with normal chromosome patterns, as well as in five patients with clonal karyotype changes, e.g., monosomy 7, trisomy 8, or loss of the Y chromosome. Being faster and approximately ten times less expensive, PRINS can replace FISH for detecting numerical karyotype changes. © 1997 by John Wiley & Sons, Ltd.     

The Art and Applications of Fluorescence In Situ Hybridization in Endocrine Pathology

Fluorescence in situ hybridization (FISH) or molecular cytogenetics is currently recognized as a reliable, sensitive, and reproducible technique for identifying the copy number and structure of chromosomes. FISH combines molecular genetics with classic cytogenetics and allows simultaneous morphologic evaluation on a single slide. Centromeric DNA probes are used to detect specific chromosomes and telomeric probes to demonstrate all chromosomes. Sequence-specific probes can localize in situ a single gene copy on a specific chromosome locus. FISH allows cytogenetic investigation of metaphase spreads and interphase nuclei. Several protocols have been proposed to analyze preparations from fresh samples or archival material. Comparative genomic hybridization (CGH) is a novel cytogenetic technique, which combines FISH with automatic digital image analysis. Comparative analysis of the hybridization products of tumor DNA and reference DNA with normal metaphase chromosomes, each labeled with color different fluorochrome, can retrieve chromosomal imbalances of the entire genome in a single experiment. FISH and CGH are powerful morphologic tools in understanding physiologic mechanisms and in resolving problems of the pathogenesis of several diseases. These techniques shed light on the cytogenetic background in many endocrinological disorders, providing a better understanding of the activities and alterations of endocrine cell function.     

Determination of allelic deletion of multiple endocrine neoplasm type 1 (MEN1) gene in acute myeloid leukemia (AML) by application of FISH-TSA technique

We have used the single and dual color fluorescence in situ hybridization (FISH) technique combined with a new detection system, tyramide signal amplification (TSA), by using the multiple endocrine neoplasm type 1 (MEN1) gene and chromosome 11 specific alpha satellite DNA probes for the study of the allelic deletion of the MEN1 gene. The MEN1 gene is a new tumor suppressor gene and has been recently cloned on chromosome 11q13. FISH combined with the TSA detection system was performed on bone marrow interphase nuclei of 22 patients with acute myeloid leukemia (AML). The FISH-TSA analysis revealed the mono allelic deletion of the MEN1 gene in 4 out of 22 patients (18.18%), 2 of 9 AML-M2 patients (22.2%), 1 of 6 AML-M4 patients (16.6%), and 1 of 4 AML-M5 patients (25.0%). Our study indicates that allelic deletion of the MEN1 gene is not a major cause or a primary event in tumorigenesis of AML, although the long arm (q13 region) of chromosome 11 involves a chromosomal rearrangement in AML.     

Effect of cytochalasin B on the induction of chromosome missegregation by colchicine at low concentrations in human lymphocytes.

The aim of the present work was to investigate the possible interference of cytochalasin B (cyt B) with low concentration treatment with colchicine in the induction of chromosome/chromatid loss and micronuclei in human lymphocytes mitotically activated in vitro. Thus, cells from a single female donor were treated with colchicine (10 or 25 nM, from 24 h after PHA addition to fixation at 66 h) either in the presence or absence of cyt B. Single lagging chromosomes/chromatids were scored in bipolar ana-telophases and greater damage (disrupted and c-anaphases) was scored in cells at anaphase. Micronuclei were scored in the first 4000 nuclei observed in both cyt B-treated (in mononucleate and binucleate cells) and untreated cultures. With the same criterion, FISH analysis was performed on 2000 nuclei where chromosome 7 and 11 centromeric DNA probes were used in pairs. Our results showed that: (i) the frequency of laggards and of micronuclei increased with colchicine concentration but in the presence of cyt B there was a lower frequency of both (with a mean reduction of approximately 49%); (ii) FISH analysis showed a colchicine concentration-dependent increase in nuclei with three spots for chromosome 7; (iii) a colchicine concentration-dependent increase in tetraploid cells was observed. This increase was particularly remarkable (5-fold) in cells grown in the presence of cyt B compared with cyt B-untreated cells. The observed 'cyt B effects' can be explained if it is assumed that in cytokinesis-blocked cells there is a shorter distance between the poles. As a consequence: (i) laggards would be engulfed in the nearest daughter nucleus with a consequent lower induction of micronuclei; (ii) segregating sister chromatids in heavily impaired anaphases would not travel a sufficient distance to give rise to two daughter nuclei, leading to an increased frequency of polyploid nuclei.     

Chromosomal aberrations in neuroblastoma cell lines identified by cross species color banding and chromosome painting

We have studied cytogenetic rearrangements in karyotypes of five neuroblastoma cell lines [SK-N-AS, SK-N-SH, SH-SY5Y, SK-N-MC, SMS-KCNR] by G-banding, cross species color banding (RxFISH), and fluorescence in situ hybridization (FISH) with chromosome painting probes. Each neuroblastoma cell line had unique modal karyotypic characteristics and showed a variable number of numerical and structural clonal cytogenetic aberrations. The number of rearranged chromosomes in SK-N-AS, SK-N-SH, SH-SY5Y, SK-N-MC, and SMS-KCNR was 11, 3, 7, 14 (tetraploid, 20-21), and 6, respectively. The origins of abnormal chromosomes were effectively analyzed by RxFISH and FISH with multiple chromosome painting probes. The chromosomal origin of the homogeneously staining region in SH-SY5Y was identified as coamplification of chromosome bands 2p13 and 2p24 by chromosome microdissection and FISH. The non-random rearrangements of chromosomes were determined on 1p34 approximately p36, 6q16 approximately q21, 8q24, 9q34, 11q13 approximately q23, 16q23 approximately q24, 17q21, and 22q31. These results may provide useful information for further molecular characterization of neuroblastoma.     

The use of fluorescent in-situ hybridization (FISH) for the analysis of in-vitro fertilization embryos: a diagnostic tool for the infertile couple

We use triple colour fluorescent in-situ hybridization (FISH)to sex human embryos for preimplantation diagnosis of X-linkeddisease, to analyse chromosome numbers in embryos donated forresearch purposes and as a diagnostic tool for patients undergoinginfertility treatment, especially in cases where abnormal embryodevelopment occurs. We have reported on the use of FISH in acase where all embryos showed accelerated cleavage. Here wereport on the use of triple colour FISH in a case where fiveout of seven oocytes were multi-nucleated when examined forpronuclei. The embryos were spread whole using HCI/Tween 20and triple colour FISH performed with probes for chromosomesX, Y and 1 in a 2 h procedure. Two embryos were normal for theprobes used, and three showed abnormalities, including one 4-cellembryo where all nuclei were X, X, X, Y, 1, 1, 1, 1. FISH indicatedthat fertilization had occurred, but that the majority of embryoswere abnormal confirming that such embryos should not be consideredfor transfer. In these cases, or where there is recurrent in-vitrofertilization failure or spontaneous abortions, embryos in futurecycles can be examined using FISH to ascertain the level ofchromosome abnormality which may aid future infertility treatment.     

Cytogenetic changes in hepatocarcinomas from rats treated with chronic exposure to diethylnitrosamine.

Cytogenetic analysis of rat hepatocarcinomas obtained after diethylnitrosamine (DEN) exposure showed a wide variety of numerical and structural chromosomal changes: 53 of 86 hepatocellular carcinomas showed at least one recurrent chromosomal aberration. Some of these recurrent changes occurred in several tumors. Chromosomes 1, 3, 11, and 12 were abnormal in more than 30% of the carcinomas; chromosomes 2, 4, 5, and 10 were abnormal in 10%. Moreover, chromosomes 1 and 10 were generally lost or deleted and chromosome 3, 4, and 11 were very often gained. The most frequent anomaly was loss of chromosome 1 which was observed in 35% of the tetraploid cell populations. The occurrence in several tumors of recurrent chromosomal rearrangements as well as various repeated aneuploidies strongly suggests that these anomalies are implicated in the process of rat hepatocarcinogenesis induced by DEN treatment.     

Unexpected retention and concomitant loss of subtelomeric regions in balanced chromosome anomalies by FISH

Florescence in situ hybridization (FISH) using subtelomeric probes has been useful in detecting cryptic telomeric chromosomal rearrangements. We report, for the first time, that cytogenetically visible chromosome rearrangements can occur between the subtelomeric and telomeric region in clinically normal individuals with balanced chromosome anomalies in which one of the breakpoints involves a terminal band region. Using FISH with subtelomeric probes, we observed in three cases with a balanced reciprocal translocations the retention and subsequent loss of subtelomeric regions. In one case with a paracentric inversion, there was a proximal relocation of a subtelomeric region. Because subtelomeric regions serve important roles in chromosome pairing, this retention and concomitant loss or relocation of a subtelomeric region could possibly further disrupt the complex meiotic configurations of these balanced chromosome rearrangements. This may then have an effect on gamete production, placing these individuals at a higher risk for miscarriages and/or abnormal outcomes for individuals with similar chromosome aberrations.     

Demonstration of the translocation der(16)t(1;16)(q12;q11.2) in interphase nuclei of ewing tumors

The der(16)t(1;16) has been detected cytogenetically in a number of malignancies including Ewing tumors (ETs). To enable fast and reliable analysis of der(16) chromosomes, we established an interphase cytogenetic approach. By using two DNA probes hybridizing to the heterochromatic portions on the long arms of chromosomes 1 and 16, this technique allows the detection of this chromosomal aberration in nonproliferating cells. Formation of the der(16) leads to partial excess of 1 q material and partial loss of the long arm of chromosome 16. Double-target fluorescence in situ hybridization (FISH) experiments were performed on cytospin slides of 13 ETs, near-triploid tumor cells and normal cells to assess whether the FISH technique used permits the discrimination of nuclei harboring this aberration from nuclei without a der(16) chromosome. In five ETs, we found evidence for the presence of one or two der(16)t(1;16) chromosomes both by FISH and by conventional cytogenetics. Tumor cells displayed two signals for intact chromosomes 1, one or two additional fused signals for the der(16) chromosomes, and one signal for the intact chromosome 16. In one case without fused signals, the presence of a der(16) was demonstrated by hybridizing a painting probe for chromosome 16 simultaneously with the paracentromeric probe for chromosome 1. Our results suggest that double-target FISH on interphase nuclei offers an ideal tool for analyzing tumors prospectively and retrospectively to assess the biological role and the possible prognostic impact of the der(16) in ETs and in other solid tumors. Genes Chromosom Cancer 17:141–150 (1996) © 1996 Wiley-Liss, Inc.     

Meier‐Gorlin syndrome (ear–patella–short stature syndrome) in an Italian patient: Clinical evaluation and analysis of possible candidate genes

Florescence in situ hybridization (FISH) using subtelomeric probes has been useful in detecting cryptic telomeric chromosomal rearrangements. We report, for the first time, that cytogenetically visible chromosome rearrangements can occur between the subtelomeric and telomeric region in clinically normal individuals with balanced chromosome anomalies in which one of the breakpoints involves a terminal band region. Using FISH with subtelomeric probes, we observed in three cases with a balanced reciprocal translocations the retention and subsequent loss of subtelomeric regions. In one case with a paracentric inversion, there was a proximal relocation of a subtelomeric region. Because subtelomeric regions serve important roles in chromosome pairing, this retention and concomitant loss or relocation of a subtelomeric region could possibly further disrupt the complex meiotic configurations of these balanced chromosome rearrangements. This may then have an effect on gamete production, placing these individuals at a higher risk for miscarriages and/or abnormal outcomes for individuals with similar chromosome aberrations. © 2002 Wiley‐Liss, Inc.     

Isolation of DNA probes specific for rat chromosomal regions 19p, 19q and 4q and their application for the analysis of diethylstilbestrol-induced aneuploidy in binucleated rat fibroblasts

DNA probes specific for rat chromosomes 19p, 19q and 4q were isolated, characterized and used for the detection and analysis of diethylstilbestrol(DES)-induced aneuploidy. By denaturing and partially reassociating total genomic DNA a new rat repetitive DNA family was isolated, which was located on chromosome 19p21. Sequencing of a number of subclones from cos76-1 and other clones of this so-called 76-family revealed that the repeat units are interrupted with large areas of other (unique) DNA. Consequently, after fluorescence in situ hybridization (FISH) the signals in interphase nuclei are large and spread out. The other two probes, cos25 (chromosome 4q) and cos42-47 (chromosome 19q), were isolated by screening cosmid libraries with probes isolated previously in our laboratory. The repeat unit of cos25 is a 2174 bp long EcoRI unit that contains three Sau3A sites and is tandemly organized. Sequencing of subclones of cos42-47 revealed that this probe was in fact the 5S RNA gene, located on 19q12. In order to determine if these probes were suitable probes for aneuploidy detection, two series of dual colour FISH with the combinations cos25/cos76-1 (4q/19p) and cos42-47/cos76-1 (19q/19p) were carried out on slides from an in vitro micronucleus assay with DES. With all three probes used, an increase in binucleated cells with non-disjunction or chromosome loss was observed in the DES-treated cultures. Scoring of additional micronucleated cells on slides hybridized with the cos25/cos76-1 (4q/19p) probes revealed that the hybridization signal of probe cos25 (4q) was over-represented in the micronuclei of the control cultures. The simultaneous use of the 19q and 19p probes is a particularly valuable tool for the detection of aneuploidy, since it allows distinction between aneugenic and clastogenic events in binucleated cells. Results of this analysis showed that apart from aneuploidy, DES also induced structural chromosome aberrations, although to a lesser extent.     

A new method to extract nuclei from paraffin-embedded tissue to study lymphomas using interphase fluorescence in situ hybridization

Fluorescence in situ hybridization (FISH) is difficult to accomplish using thin-sections of paraffin-embedded lymphoid tissue because of the high cellularity and truncated cells that interfere with accurate scoring of individual nuclei. We modified and tested a new technique to isolate individual nuclei from tissue cores of paraffin-embedded tissue processed with xylene, proteinase K, citric acid, and pepsin. The efficacy of this method to study paraffin-embedded tissue was investigated in six normal lymph nodes or tonsils and 32 malignant lymphomas including five mantle cell, five follicular, five Burkitt, five extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue, five anaplastic large-cell, and seven diffuse large B-cell. Fusion of CCND1 and IgH, BCL2 and IgH, c-myc and IgH, and MALT1 and API2 were detected using probes with a dual-fusion FISH strategy. Anomalies involving ALK and BCL6 were detected using break-apart FISH probes. FISH studies were successful for each of the 38 specimens. Chromosome anomalies were detected in each malignant specimen, but not in the normal lymphoid tissue. The correct chromosome anomaly was detected in 22 of 22 specimens with genetic abnormalities that were established by other genetic techniques. This FISH technique is useful to detect chromosome anomalies with high sensitivity and specificity in paraffin-embedded tissue and may provide important diagnostic and prognostic genetic information.     

一个涉及1号和7号染色体插入易位家系的鉴定

目的 确定一个有反复流产史且常规G显带发现有7q末端缺失病例的核型,探讨染色体末端区域插入易位的形成机理。方法 应用显微切割制备的7号特异性全染色体探针和7q亚端粒（7q36→qter)探针,与病例的中期分裂相进行荧光原位杂交（fluorescence in situ hybridization,FISH)。结果 发现了该病例为常规G显带难以妈现的1号和7号染色体之间的插入易位,7q36→qter区域没有插入到1号染色体中,其异常核型来源于其母亲。结论 为染色体末端区域的插入易位仍然为一个三断裂重排。细胞遗传学上见到的末端缺失为中间缺失提供了实验证据,FISH与显微切割技术相结合。是检出染色体微小结构异常的一个强有力的工具。     

An assessment of chromosomal alterations detected by fluorescence in situ hybridization and p16 expression in sporadic and primary sclerosing cholangitis-associated cholangiocarcinomas

The objective of this study was to assess and compare the chromosome abnormalities present in sporadic and primary sclerosing cholangitis (PSC)-associated cholangiocarcinomas (CCAs) and biliary dysplasias. Histologic sections from 22 patients with CCA (16 sporadic and 6 PSC associated), 5 of whom had associated dysplasia, and 2 PSC patients with biliary dysplasia alone were assessed for chromosomal alterations with fluorescence in situ hybridization (FISH). FISH involved the use of a multiprobe set consisting of centromere-specific probes for chromosomes 3, 7, and 17 and a locus-specific probe for 9p21. The number of signals for each of these probes was enumerated in 50 nonoverlapping interphase nuclei, and the percentage of nuclei containing 0, 1, 2, and 3 or more signals was recorded for each probe. p16 expression was assessed using immunohistochemistry. Gain of at least 1 chromosome was identified in 19 of 22 (86%) invasive tumors and in 4 of 7 (57%) biliary dysplasias. Gain of 2 or more chromosomes (polysomy) was observed in 17 of 22 (77%) invasive tumors and in 3 of 7 (43%) biliary dysplasias. Homozygous loss of 9p21 was identified in 11 of 22 (50%) invasive tumors and in 3 of 7 (43%) biliary dysplasias. The patterns of chromosomal abnormalities detected by FISH in PSC-associated and sporadic CCAs were similar. Nine of 13 (69%) invasive tumors and 2 of 5 (40%) biliary dysplasias with complete loss of p16 expression by immunohistochemistry showed allelic loss of 9p21 by FISH. Polysomy and homozygous 9p21 deletion are common in both sporadic and PSC-associated CCAs and are frequently detectable in PSC-associated biliary dysplasia.     

Interphase cytogenetics of gastric carcinoma: Fluorescence in situ hybridization (FISH) applied to cells obtained from formalin-fixed paraffin-embedded tissues

The interphase cytogenetics in formalin-fixed and paraffin-embedded gastric cancer tissues were examined by fluorescence in sku hybridization (FISH) with α-satellite DNA probes. Two gastric carcinoma cell lines, TMK-1 and MKN-28, were first analyzed cytogenetically. Of 25 TMK-1 cell karyotypes, chromosome 7 showed trisomy and chromosome 17 showed disomy in 18 cells. Most MKN-28 cells showed disomy of both chromosomes 7 and 17. Suspensions of singly isolated TMK-1 and MKN-7 cells were obtained from the cultured cells, and from paraffinembedded tissue specimens fixed with formalin for 0, 1, 3 and 5 days obtained from xenotrans-planted tumors in nude mice. The numbers of chromosomes 7 and 17 analyzed with the karyotypic preparations coincided well with those determined by FISH, even in the paraffin-embedded specimens. The number of tumor cells showing no signals, however, increased in the specimens after 5 days formalin fixation. In 10 surgically removed gastric carcinomas, the predominant signal number for chromosomes 7 and 17 in the cells of paraffinembedded tissues was two (disomy), except in one papillary carcinoma, which was trisomic for chromosome 7. Large subpopulations (more than 20%) showing trisomy were found in four cases for chromosome 7 and in five cases for chromosome 17. A higher frequency of trisomy was found in well differentiated than in poorly differentiated carcinomas. These findings suggest that the FISH technique is a useful tool for detecting chromosomal aberrations in gastric adenocarcinoma cells, even in paraffinembedded specimens, as long as the tissues are fixed with formalin for an appropriate time.     

一种能精确检测人间期细胞核中21号染色体拷贝数的DNA探针

目的制备能精确检测人类间期细胞核中２１号染色体拷贝数的ＦＩＳＨ探针。方法利用万能引物ＰＣＲ法,从定位于人２１ｑ１１的ＹＡＣ克隆８８１Ｄ２分离制备ＤＮＡ探针,并用于与８例正常人和５例２１三体患者的外周血淋巴细胞中期相和间期核,及经细胞松弛素Ｂ（ｃｙｔｏｃｈａｌａｓｉｎＢ）诱导的双核细胞进行ＦＩＳＨ分析。结果该探针具有以下特点：（１）长度集中于３５０～７５０ｂｐ;（２）其靶序列位于２１号染色体长臂上且紧靠着丝粒;（３）特异性强;（４）杂交信号明亮,容易辨认;（５）对中期相及间期细胞核中２１号染色体的检出率分别高达９９．６０％和９８．４０％。结论制备的ＤＮＡ探针能精确检测人类间期细胞核中２１号染色体的拷贝数,且适用于细胞分裂时２１号染色体分离情况的研究