9号环状染色体综合征的荧光原位杂交分析

目的 对1例9号环状染色体综合征患儿进行细胞分子遗传学分析,探索9号环状染色体与临床表型的关系.方法 采用染色体G显带核型分析和TelVision 9p探针和TelVision 9q探针进行双色荧光原位杂交,识别和定位1例9号环状染色体患儿.结果 患儿核型为45,X,-9/46,XX,r(9)(p24q34)/46,XX,r(9;9)(p24q34;p24q34)(4/92/4).双色荧光原位杂交显示9号环状染色体上没有杂交信号,提示9号环状染色体短臂末端缺失片段至少有115 kb,长臂末端缺失片段至少有95 kb.与其它报道的环状9号染色体综合征、9号染色体短臂和长臂部分单体综合征相比,本例患者兼有环状9号染色体综合征的临床特征以及9号染色体短臂和长臂部分单体综合征的一些特征.结论 由于缺失的断裂点之间亚显微结构的不同、环的不稳定性、基因与表型相互作用以及胎儿环境条件的不同等原因,具有相同断裂点的9号环状染色体综合征患者可以有不同的临床表型,单倍基因剂量不足对临床表型发挥了重大作用.     

一例环状X染色体嵌合体Turner综合征的双色荧光原位杂交

目的通过对1例环状X染色体嵌合体的细胞遗传学分析，探讨环状X染色体形成的原因，临床表现与染色体核型的关系。方法应用染色体G显带技术对环状染色体进行识别，并选用DXZ1和DYZ3探针，通过双色荧光原位杂交技术进一步确认环状染色体来源。结果患儿染色体核型为45，X[83]／46，X，r（X）（p22．1q22）[16]／47，X，2r（X；X）（p22．1q22；p22．1q22）[1]。双色荧光原位杂交示ish（DYZ3-）r（x）（DXZ1＋）。结论具X染色体大环的染色体核型非常罕见，Turner综合征患者的临床表型和染色体核型存在依赖性，对于青春前期身材矮小的女性患儿应高度警惕X染色体的异常。     

环状13号染色体的细胞遗传学分析

目的 对1例产前诊断嵌合型13号环状染色体病例进行遗传学分析,结合国内外报道文献探讨其发生机制及基因型-表型研究,为临床遗传咨询提供参考.方法 应用常规G显带染色体核型分析胎儿的染色体核型.结果 G显带胎儿核型为46,XX,r(13)[25]/45,XX,-13[24]/46,XX,-13,+mar[5]/47,XX,...     

21号环状染色体的细胞遗传学分析

目的通过对1例21号环状染色体嵌合体患者的细胞遗传学分析,探讨21号环状染色体的形成原因,临床表型与染色体区带及嵌合比例的关系。方法应用染色体常规标本、G显带、C显带技术对21号环状染色体进行识别与区带定位。结果患者核型为mos46,XX,r（21）（pllq22）[91]／45,XX,-21[5]／46,XX,dicr（21;21）（pllq22;p11q22）[4]。结论环状染色体断裂位点在21pll和q22,21号环状染色体综合征的临床表现与核型嵌合比例及21q末端缺失的多少相关,女性不孕可能与21q22片段的缺失相关。     

二例环状染色体综合征的遗传学分析

环状染色体综合征是一种较罕见的染色体病,最近我室发现2例顶端着丝粒染色体环状综合征,现报道如下.     

Turner综合征患者X环状染色体细胞遗传学效应分析

目的本文报道4例45,X/46,X,r（X）Turner氏综合征的临床表现及细胞遗传学检查情况,对环形成的机理及其与临床表现的关系进行了讨论。各种不同类型及数目的环,其形成主要决定于细胞分裂过程中姐妹染色单体是否发生交换,以及交换发生的次数。临床表现决定于45,X细胞系占的比例,以及r（X）两端丢失片断的大小。     

分子细胞遗传学技术诊断一例3号环状染色体综合征

目的 对1例发育迟缓伴先天性心脏病的患儿进行分子细胞遗传学分析,寻找其病因。 方法 对患儿及其父母进行常规染色体G显带核型分析和染色体微阵列分析。 结果 染色体G显带核型分析结果显示患儿为3号环状染色体综合征,其父母核型正常;染色体微阵列分析结果显示患儿存在染色体3q26.3-25.3片段缺失,该区域涉及45个基因的大片段缺失,未发现其他区段存在致病性的基因变异,患儿父母染色体微阵列分析未见异常。 结论 3号环状染色体综合征的临床表现主要取决于缺失片段包含的基因。染色体微阵列分析技术可为临床诊断提供准确的基因变异信息,但对环状染色体相关疾病的诊断仍需结合染色体核型分析结果。     

环状染色体患儿12例的临床表型及遗传学分析

目的 探讨环状染色体在儿童生长发育期的发生率,分析其临床表型和遗传学特征。 方法 选取2015年1月至2021年8月因生长发育异常就诊的儿童7 574例,采集其外周血样进行G显带染色体核型分析。 结果 在7 574例患儿中,共检出12例环状染色体,检出率为0.16%,具体包括1例r(6)、2例r(9)、2例r(13)、1例r(14)、2例r(15)、1例r(21)以及3例r(X)。12例患儿均存在不同程度的表型异常,包括生长发育迟缓、智力低下、肢体畸形、先天性心脏病等。在具有相同断裂位点的2例r(9)患儿和2例r(15)患儿中,各有1例仅表现为生长发育迟缓,其余2例则合并r(9)有特殊面容、复杂先天性心脏病等。携带r(X)的患儿具有Turner综合征的部分表现。 结论 环状染色体是导致儿童生长发育及智力异常的重要原因,其临床表型复杂多样,临床医师应仔细采集这类患儿的病史,并尽早完善染色体检查以明确诊断。     

嵌合型4号环状染色体患儿1例的遗传学分析

目的 探讨1例嵌合型4号环状染色体患儿核型的成因、临床表型及发病机制。 方法 选取2020年2月15日于滕州市妇幼保健院就诊的1例嵌合型4号环状染色体患儿为研究对象。收集患儿的临床资料,对其进行外周血染色体G显带核型分析、染色体微阵列分析(CMA)、荧光原位杂交(FISH)检测,并对文献进行回顾。 结果 患儿为足月小样低体重儿,具有特殊面容、动脉导管未闭、室间隔缺损。外周血染色体核型为mos 46,XY,r(4)(p16.3q35.2)[259]/45,XY,-4[25]/47,XY,r(4)(p16.3q35.2),+r(4)(p16.3q35.2)[8]/46,XY,der(4)del(4)(p16.3)inv(4)(p16.3q31.1)[6]/46,XY,dic？r(4;4)(p16.3q35.2;p16.3q35.2)[4]/48,XY,r(4)(p16.3q35.2),+r(4)(p16.3q35.2)×2[3]/46,XY,r(4)(p1？q2？)[2];CMA检测结果为arr[GRCh37]4p16.3(68 345-2 981 614)×1;FISH检测结果为45,XY,-4[12]/45,XY,-4×2,+mar1.ish r1(4)(WHS-,D4Z1+)[1]/46,XY,-4,+mar1.ishr1(4)(WHS-,D4Z1+)[73]/46,XY,-4,+mar2.ishr2(4)(WHS-,D4Z1++)[1]/47,XY,-4,+mar1×2.ishr1(4)(WHS-,D4Z1+)×2[4]/46,XY,del(4)(p16.3)．ish del(4)(p16.3)(WHS-,D4Z1+)[9]。 结论 患儿的4号环状染色体为新发变异,在胚胎发育过程中产生了多种细胞系,形成同源嵌合体。4号环状染色体综合征临床表型多变,与其本身的不稳定性、是否存在嵌合体核型、是否伴有缺失/重复及其范围等有关。     

一例13号环状染色体核型分析

一例１３号环状染色体核型分析肖勇白秀英王维人王秀岩张显峰吕学冼环状１３号染色体综合征是一种罕见的染色体综合征，患者一般具有虹膜或视网膜缺损，白内障或视网膜母细胞瘤［１］。视网膜母细胞基因现已定位到１３ｑ１４上，在实体瘤中常见的染色体改变是１３单体或涉...     

Molecular analysis of chromosome 21 in a patient with a phenotype of down syndrome and apparently normal karyotype

Down syndrome (DS) is caused in most cases by the presence of an extra chromosome 21. It has been shown that the DS phenotype is produced by duplication of only a small part of the long arm of chromosome 21, the 21q22 region, including and distal to locus D21S55. We present molecular investigations on a woman with clinically typical DS but apparently normal chromosomes. Her parents were consanguineous and she had a sister with a DS phenotype, who died at the age of 15 days. Repeated cytogenetic investigations (G-banding and high resolution banding) on the patient and her parents showed apparently normal chromosomes. Autoradiographs of quantitative Southern blots of DNAs from the patient, her parents, trisomy 21 patients, and normal controls were analyzed after hybridization with unique DNA sequences regionally mapped on chromosome 21. Sequences D21S59, D21S1, D21S11, D21S8, D21S17, D21S55, ERG, D21S15, D21S112, and COL6A1 were all found in two copies. Fluorescent in situ hybridization with a chromosome 21-specific genomic library showed no abnormalities and only two copies of chromosome 21 were detected. Nineteen markers from the critical region studied with polymerase chain reaction amplification of di- and tetranucleotide repeats did not indicate any partial trisomy 21. From this study we conclude that the patient does not have any partial submicroscopic trisomy for any segment of chromosome 21. It seems reasonable to assume that she suffers from an autosomal recessive disorder which is phenotypically indistinguishable from DS. © 1996 Wiley-Liss, Inc.     

Familial transmission of a ring chromosome 21

A ring chromosome 21 was found in a phenotypically normal mother and her son. The clinical findings in the son were bilateral retention of the testes and a slightly delayed puberty onset. Consequences of a ring formation of a chromosome 21 in phenotypically normal patients are presented and discussed, and the previously reported cases of familially transmitted G-group ring chromosomes are reviewed.     

Characterization of a ring chromosome 21 by FISH-technique

Ring chromosomes 21 that contain two copies of the Down syndrome critical region (DCR1), thereby contributing to trisomic dosage, have not been fully characterized by routine cytogenetic methods in the past. We therefore employed the fluorescence in situ hybridization (FISH) technique, using a battery of chromosome 21 probes and conclude that the ring resulted from a centromere to centromere and long arm to long arm fusion that contains alpha-satellite DNA and two copies of the D21S65 locus, but lacks beta-satellite DNA and telomeric DNA. Consequently, we suggest that the origin of the ring may be due to the misdivision of the centromere following the duplication of the long arm, forming a monocentric isochromosome followed by breakage in a region distal to the D21S65 locus and proximal to the telomeric sequences followed by reunion of the broken ends resulting in a monocentric ring. Different ring configurations or fragments were not detected, suggesting that the ring chromosome was highly stable. Apparently, the presence of two copies of Down syndrome loci within the ring chromosome, along with one copy on the normal homologue, caused the clinical consequences of Down syndrome.     

Supernumerary ring chromosome 20 characterized by fluorescence in situ hybridization

We report on a boy with mild dysmorphic features and developmental delay, in whom karyotyping showed an additional minute ring chromosome in 60% of metaphases. Fluorescence in situ hybridization (FISH) with a centromere specific probe demonstrated that the ring chromosome contained the centromeric region of chromosome 20. The ring was highlighted completely using a chromosome 20 painting probe. A cosmid probe for 20p12-13 gave a positive signal and hybridization with an all-telomere probe showed one signal, suggesting a breakpoint in the 20p telomere. The results suggested that only a small part of 20q was involved in this ring. The ring was also detected in 18% of nuclei of a buccal smear. The phenotypic similarities of symptoms in the proband to patients with a (partial) trisomy 20p and the dissimilarities to symptoms in patients with (partial) trisomy 20q were in agreement with the FISH results.     

CB-FISH法检测人体内嵌合的21号染色体非整倍体

目的　探讨 2 1三体患者体内二倍体细胞增多的机理。方法　用松胞素 - B诱导的双核细胞荧光原位杂交技术 ,对人体内 2 1号染色体非整倍体和培养细胞中 2 1号染色体分离异常的发生率进行检测。结果　 2 1三体患者体内 ,二倍体细胞率 (16 .90‰± 10 .70‰ )远高于 2 1四体细胞率 (0 .42‰± 0 .6 4‰ ) (P=0 .0 0 0 )。在培养的正常人和 2 1三体患者细胞中 ,2 1号染色体不分离率 (3.6 9‰± 2 .5 0‰和 8.2 2‰±5 .5 4‰ )显著高于丢失率 (0 .10‰± 0 .30‰和 0 .43‰± 0 .49‰ ) (P=0 .0 0 0 )。结论　 2 1三体患者体内较高比例的二倍体细胞源于因三体细胞中 2 1号染色体分离异常而形成的二倍体细胞的逐渐积累     

Turner综合征患儿标记染色体的来源研究

目的 了解Turner综合征患儿标记染色体的来源，以指导遗传咨询及治疗。方法 在染色体核型分析的基础上，对32例Turner综合征患者进行回顾性分析。对3例含有标记染色体的患儿进一步用荧光原位杂交技术研究标记染色体的来源。结果 3例含有标记染色体的Turner综合征患儿中，确定1例患儿的标记染色体来源于Y染色体，含有性别决定基因；1例来源于X染色体；另外1例未能确定其来源，该标记染色体可能来源于性染色体的其他片段或其他端着丝粒染色体。结论 Turner综合征患者的标记染色体大多来源于性染色体（X染色体、Y染色体），也可能来源于其他端着丝粒染色体。有必要同时应用X染色体和Y染色体特异性探针对Turner综合征患者进行标记染色体的荧光原位杂交分析，以明确标记染色体的来源。     

Supernumerary ring chromosome 17 identified by fluorescent in situ hybridization

We present a patient with multiple anomalies and severe developmental delay. A small supernumerary ring chromosome was found in 40% of her lymphocyte cells at birth. The origin of the marker chromosome could not be determined by GTG banding, but fluorescent in situ hybridization (FISH) later identified the marker as deriving from chromosome 17. Am. J. Med. Genet. 69:35–355, 1997. © Wiley-Liss, Inc.     

Marker chromosome 21 identified by microdissection and FISH

A child without Down syndrome but with developmental delay, short stature, and autistic behavior was found to be mosaic 46,XX/47,XX,+mar(21) de novo. The marker was a small ring or dot-like chromosome. Microdissection of the marker was performed. The dissected fragments were biotinylated with sequence-independent PCR as a probe pool for fluorescence in situ hybridization (FISH). FISH results suggested an acrocentric origin of the marker. Subsequent FISH with α-satellite DNA probes for acrocentric chromosomes, and chromosome-specific 21 and 22 painting probes confirmed its origin from chromosome 21. © 1995 Wiley-Liss, Inc.     

Cytogenetic and molecular analysis of a ring (21) in a patient with partial trisomy 21 and megakaryocytic leukemia

We describe a patient with an asymmetric double ring 21 in mosaic form, 45,XX,-21/46, XX,-21,+r(21), who has limited manifestations of Down syndrome and who developed acute myelofibrosis and megakaryocytic leukemia (AMKL), FAB M7, a hematologic disorder particularly common in Down syndrome patients. In situ hybridization studies, gene dosage, and DNA polymorphism analysis showed that the ring chromosome carries a duplicated region which extends from D21S406 on the centromeric side and includes marker D21S3 on the telomeric side. FISH studies indicate two sizes of ring 21 in the patient. The origin of the supernumerary chromosome 21 in the proband was paternal; furthermore, the r(21) probably was formed postzygotically. Included in the duplicated segment are the candidate genes for leukemia AML-1, ETS, and ERG. The potential significance of disomic homozygosity of loci on 21q in M7 megakaryocytic leukemia is discussed. © 1995 Wiley-Liss, Inc.