2例15q11-q13微重复胎儿病例的遗传学分析

目的 探讨产前诊断中联合应用染色体拷贝数变异检测（CNV-seq）、甲基化MLPA和染色体显带技术对15q11-q13微重复在遗传学分析的临床价值。方法 对2例15q11.2-q13.2微重复病例采用CNV-seq、G显带、C显带和MS-MLPA技术进行羊水标本检测，异常结果行家系验证和溯源分析。结果 胎儿A:15q11.2-q12和15q12-q13.1分别重复4.96Mb和0.84Mb，其羊水细胞核型为47,XX,+psuidic(15)(q13)，父母染色体核型分别为46,XY和47,XX,+psu idic(15)(q13)。胎儿B:15q11.2-q13.2和15q13.2-q13.3分别重复7.64 Mb和1.46 Mb；其羊水细胞核型为47,XX,+mar，父母染色体核型正常；MS-MLPA溯源分析提示胎儿B为父源性重复。结论 通过染色体显带和变异溯源等方法明确了2例患儿拷贝数异常来源，为该疾病产前诊断提供了可行联合方案，并为研究15q11-q13区域拷贝数变异积累了数据。     

1例罕见母源性11q及22q部分三体胎儿的产前诊断及遗传学分析

目的 对1例血清学筛查21三体高风险伴有侧脑室增宽的胎儿进行遗传学诊断。方法 联合应用常规G显带核型分析技术及CNV-seq测序技术对胎儿进行遗传学检测，并对双亲进行外周血染色体核型分析以明确胎儿染色体异常的来源。结果 胎儿染色体初步为47,XX,+mar。CNV-seq结果提示胎儿11q23.3-11q25存在18.25Mb重复，22q11.21-22q11.21存在1.35Mb重复。胎儿父亲染色体正常，母亲染色体为46,XX,t(11;22)(q23;q11.2)。胎儿核型结果最终确定为47,XX,+der(22)t(11;22)(q23;q11.2)。结论 胎儿携带有母源性11q部分三体和22q部分三体，可能导致严重的临床表型；明确胎儿的遗传学病因，指导家庭再次生育。     

SNP芯片技术产前鉴别额外小标记染色体

目的 用SNP芯片技术对1例产前发现的疑难额外小标记染色体(small supernumerary marker chromosome,sSMC)进行鉴定,明确其遗传物质的来源并推测其发生机制.方法 对1例染色体核型分析提示携带来源不明sSMC的胎儿进行SNP芯片全基因组扫描检测,结果用荧光原位杂交技术(fluorescence in situ hybridization,FISH)验证.结果 胎儿染色体核型示46,X,+mar,芯片结果确定sSMC为Yp11.2-11.3重复、Yq11.2区域缺失,FISH结果证明sSMC来源于Y染色体.结论 明确胎儿核型为46,X,idic(Y)(pter→ p11.2∶∶11.2→pter).Yq11.2区的缺失与男性无精症相关.芯片技术可一次性排除23对染色体大于1 Mb的微缺失和重复,明确遗传学机制,适用于疑难病例的鉴别和微缺失重复综合征的产前诊断.     

微阵列比较基因组杂交技术在染色体异常细胞遗传学分析中的应用

目的分析染色体G显带核型异常患者基因拷贝数变异(CNVs)情况,探讨微阵列比较基因组杂交(array CGH)技术在染色体异常细胞遗传学分析中的作用。方法收集受试者外周血标本,array CGH技术分析染色体易位、标记染色体以及性染色体异常患者CNVs情况及其临床意义。结果 array CGH分析发现染色体核型为45,XY,t(18;21)(18p11;21p11),15ps+的易位患者染色体18p11.3存在缺失,17q21.31存在扩增,18号染色体与21号染色体为非平衡易位,未检测到染色体15ps+相关CNVs;核型为47,XX,15ps-,+mar患者存在Y染色体相关CNVs,其标记染色体可能来源于Y染色体;核型为45,X/46,XY的性染色体异常患者染色体15q11.2存在缺失、15q13.3和22q11.23存在扩增,未检测到性染色体数目异常相关CNVs。结论 array CGH技术在临床细胞遗传学分析中具有重要的价值,该技术应用于CNVs分析有利于筛查病理性CNVs,明确染色体易位类型,辅助了解标记染色体的来源,但可能不适用于嵌合体以及染色体随体异常的检测。     

9p重复伴8p末端缺失胎儿的遗传学分析并文献复习

目的对1例产前异常胎儿及其双亲行细胞遗传学及分子遗传学研究,以明确胎儿异常遗传物质的来源及其发生机制。探讨染色体微阵列分析(Chromosomal Microarray Analysis,CMA)在临床产前诊断中的临床价值。方法对患儿脐血及其双亲外周血进行常规G显带分析,进一步应用CMA对患儿进行全基因组拷贝数分析。结果 G显带核型分析提示胎儿脐血染色体核型结果为46,XX,der(8)(?::p23→qter),其母亲外周血核型结果为46,XX,t(8,9)(p23,p22),父亲核型未见异常。胎儿衍生8号染色体来源于携带平衡易位染色体的母亲。CMA检测提示胎儿存在9p21.3-p24.3区域22.666Mb的重复片段及8p23.2-p23.3末端4.413Mb的缺失片段。胎儿核型最终修正确定为46,XX,der(8)t(8,9)(p23.2,p21.3)mat。结论胎儿染色体9p重复伴8p末端缺失可能造成出生后的严重异常表型,本文对该患胎进行了产前诊断及遗传学分析,为临床产前诊断和遗传咨询提供了有力依据。     

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,...     

三例畸变Y染色体的重组形式及定位分析

目的 对3例畸变Y染色体进行定位分析并确定其重组形式.方法 采用染色体G显带、多重连接依赖探针扩增(multiplex ligation dependent probe amplification,MLPA)、荧光原位杂交(fluorescence in situ hybridization,FISH)、Y染色体多个序列标签位点(sequence tagged site,STS)及Illumina人类全基因组单核苷酸多态性芯片扫描(single nucleotide polymorphisms array,SNP-array)等多种技术.结果 3例患者染色体G显带核型均为46,X,+ mar.MLPA检测发现例1 SRY、ZFY、UTY基因重复;例2 SRY、ZFY基因重复、UTY基因缺失;例3X染色体短臂/Y染色体短臂(X/Yp)、X染色体长臂/Y染色体长臂(X/Yq)亚端粒区域基因拷贝数减少.Y染色体STS分析提示:例1的SRY及Y染色体AZFa区sY84、sY86、AZFb区sY1227存在,但sY1228及AZFc区多个STS缺失,断裂点位于AZFb区sY1227和sY1228之间;例2的SRY及着丝粒区域sY1200存在,其余STS均缺失;例3的SRY及AZF多个STS均存在.SNP-array扫描提示,例1 Yp11.31-p11.2区重复,Yq11.22-q11.23区缺失,缺失片段约为5.18 Mb;例2 Yp11.31-p11.2区重复,重复片段为3.724 Mb,Yq11.21-q11.23区域缺失,缺失约14.644Mb;例3 X/Yp亚端粒区域(PAR) p22.33单拷贝缺失,X/Yq亚端粒区域(PAR) q28单拷贝缺失.FISH分析提示,例1和例2细胞中期原位杂交核型均为46,X,+ mar.ish(Y)(SRY++,DYZ3++,DYZ1-).综合分析:例1和例2的标记染色体均为短臂等臂双着丝粒Y染色体.分子核型:例1为46,X,idic (Y)(q11.23);例2为46,X,idic(Y) (q10);例3为标记染色体为环状Y,核型为46,X,r(Y)(p1 1q12).结论 Y染色体畸变形式多样,选用MLPA、Y染色体STS、FISH、SNP-array等多项技术联合诊断是确定其断裂点及重组形式的重要手段.     

应用单核苷酸多态芯片技术产前诊断四例胎儿新发染色体变异

目的 探讨单核苷酸多态性芯片(single nucleotide polymorphisms array,SNP-array)技术在新发染色体变异产前诊断中的应用价值.方法 选取产前诊断G显带染色体核型为新发平衡易位或微小额外标记染色体的4名孕妇,知情同意抽取胎儿脐带血DNA,按照标准的微阵列操作手册进行杂交、洗涤及全基因组扫描,扫描数据通过相应的计算机软件进行分析.结果 例1未发现致病性拷贝数改变;例2嵌合的微小额外标记染色体来源于4号染色体,包含约9Mb的重复;例3除了遗传了来源于母亲的两条平衡易位染色体,还出现了两条新发的易位染色体,但SNP-array未发现致病性拷贝数改变;例4的G显带显示的两条"平衡"易位染色体实为不平衡畸变:1号染色体25Mb的重复和9号染色体17Mb的缺失.例1和例3出生后随访智力体格发育均未见异常.结论 SNP-array能够在DNA水平上甄别胎儿新发"平衡"易位或微小额外标记染色体的致病性,在产前诊断中不失为传统染色体核型分析的重要补充.     

一例idic(15)来源的嵌合型标记染色体的遗传学分析

目的:应用细胞遗传学和分子生物学检测方法明确1例嵌合型标记染色体患者的核型及其来源。方法:抽取患者的外周血样,进行染色体核型分析、基因芯片检测和荧光原位杂交检测。结果:染色体分析结果显示患者核型为mos 47,XX,+mar [45]/48,XX, +2mar[3]/ 46,XX[52];基因芯片检测结果为arr[hg...     

应用微阵列比较基因组杂交技术对胎儿复杂染色体易位的产前诊断

目的对产前羊水细胞培养染色体核型分析,检测出染色体易位的胎儿应查父母双方染色体,并用基于芯片的微阵列比较基因组杂交(array comparative genomic hybridization,a CGH)技术检测,以明确其易位染色体的来源及胎儿染色体有无微重复或微缺失,探讨微阵列比较基因组杂交(a CGH)技术在检测胎儿染色体异常中的临床价值。方法通过胎儿羊水细胞培养,染色体G显带核型分析,诊断出胎儿染色体异常,核型为46,X,t(X;13;9)(q13;q14;p22),t(3;6)(p13;q23)。对此例标本进行a CGH分析,通过多位点高分辨率扫描确定胎儿染色体有无微重复或微缺失。结果a CGH扫描检测出胎儿染色体在Xq13.1-q13.2(71,699,190-71,820,393)区带存在121kb的缺失,在13q14.2-q21.1(48,706,590-57,520,639)区带存在8.8Mb的缺失。结论利用a CGH技术可以方便快速地鉴定和分析染色体的微重复或微缺失,结合传统的核型分析技术,可以为判断重复或缺失染色体片段的遗传学效应和产前诊断提供帮助。     

Partial duplication 16p resulting from a 3:1 segregation of a maternal reciprocal translocation

We report on a male infant with a duplication 9p (pter → _q13) and duplication 16p (p13 → pter) resulting from a 3:1 meiotic disjunction of a maternal reciprocal translocation. In this case, the mode of segregation fits to the Pachytene-Diagram Model of Jalbert el al [1980]. The infant showed clinical features that have been described both in dup(16p) and in dup(9p). To our knowledge, this is the first time that this unbalanced karyotype has been reported.     

Two inv dup(15) chromosomes in a woman with repeated abortions

A 40‐year‐old, phenotypically normal woman, with a history of two repeated abortions and no child, had two additional, small, bisatellited, and apparently metacentric chromosomes. Various banding and microsatellite analyses indicated that the additional chromosomes were inv dup(15)(q11q11) without the Prader‐Willi/Angelman syndromes critical region, and therefore without phenotypic effects. Her father had a single, identical additional inv dup(15) chromosome. Her husband was chromosomally normal, but sperm analysis indicated a reduced motility and a reduced frequency of morphologically normal sperm. In view of these findings, it was deduced that the inv dup(15) chromosome in the father was transmitted in duplicate to the woman. Individuals with two additional inv dup(15) chromosomes in the literature were reviewed, and possible correlation of the two additional inv dup(15) chromosomes in the woman and her repeated abortions was discussed. © 2001 Wiley‐Liss, Inc.     

Familial t(11;13)(q21;q14) and the duplication 11q, 13q phenotype

Cases of duplication of distal 11q or proximal 13q have been reported independently. A specific translocation resulting in duplication of distal 11q, [der(22)t(11;22)(q23;q11)], has been documented in over 40 cases. We report on a male fetus with chromosomal excess of both distal 11q and proximal 13q resulting from a familial translocation. This case supports the causal association of duplication 11q with neural tube defects. © 1993 Wiley-Liss, Inc.     

De novo inverted interstitial (“mirror”) duplication of chromosome 8(q13→q24.1) in a liveborn male

We report on a newborn boy with a de novo inverted interstitial duplication of chromosome 8(q13→q24.1). This form of cytogenetic abnormality, in which a mirror image interstitial duplication has occurred, is exceedingly rare. Review of the literature and mechanisms to explain the origin of this type of chromosome aberration are presented. A review of the findings from individuals with partial dup(8q) demonstrate remarkable similarity to the infant we describe.     

Characterization of an inversion duplication of the short arm of chromosome 8 by fluorescent in situ hybridization

A de novo chromosome aberration in a woman with severe mental retardation and minor anomalies has been characterized cytogenetically. The patient's karyotype was described as 46, XX, inv dup (8)(p12 → p23.1). Previous Southern blot dosage studies with the marker locus D8S7 demonstrated that the patient was monosomic for this locus, suggesting that the rearrangement generated a duplication-deficiency chromosome. We have reinvestigated this patient using fluorescent in situ hybridization with chromosome 8 cosmids and an Alu-PCR product specific for 8p. These studies have confirmed directly that the duplicated chromosome also has undergone deletion. © 1992 Wiley-Liss, Inc.     

Prenatal diagnosis of a dup(3p) with holoprosencephaly

The prenatal diagnosis of dup(3p) was made in a female conceptus, the father being a known carrier of a balanced translocation t(3;10)(p21;q26). Interruption of pregnancy at 19 weeks showed a fetus with a holoprosencephaly field defect. Two other cases of dup(3p) have been observed in the same family. The malfor-mations were different in each of the 3 patients, suggesting a considerable degree of variability of dup(3p).     

U-type exchange in a paracentric inversion as a possible mechanism of origin of an inverted tandem duplication of chromosome 8

A mentally retarded male with dysmorphic features was found to have a de novo 46,XY,inv dup(8) (p.23.1 → 12). Confirmation of the segments duplicated in the rearrangement was achieved by biochemical analysis of glutathione reductase, which maps to 8p21.1, and DNA studies using the chromosome specific probe y-19-1D (D85131), which maps to 8p21. Assay of cathepsin B, which has been localised to 8p22, did not differ from controls with normal chromosomal constitution. DNA studies using the Defensin 1 gene probe, which maps to 8p23, showed a previously undetected deletion of that segment. We propose that the inverted tandem duplication/deletion arose as a single U-type exchange within an inversion loop. © 1994 Wiley-Liss, Inc.     

Supernumerary inv dup(15) in a patient with Angelman syndrome and a deletion of 15q11–q13

We have studied a patient with Angelman syndrome (AS) and a 47,XY,+inv dup(15) (pter→q11::q11→pter) karyotype. Molecular cytogenetic studies demonstrated that one of the apparently normal 15s was deleted at loci D15S9, GABRB3, and D15S12. There were no additional copies of these loci on the inv dup (15). The inv dup (15) contained only the pericentromeric sequence D15Z1. Quantitative DNA analysis confirmed these findings and documented a standard large deletion of sequences from 15q11-q13, as usually seen in patients with AS. DNA methylation testing at D15S63 showed a deletion of the maternally derived chromosome. AS in this patient can be explained by the absence of DNA sequences from chromosome 15q11-q13 on one of the apparently cytogenetically normal 15s, and not by the presence of an inv dup (15). This is the fourth patient with an inv dup (15) and AS or Prader Willi syndrome, who has been studied at the molecular level. In all cases an additional alteration of chromosome 15 was identified, which was hypothesized to be the cause of the disease. Patients with inv dup (15)s may be at increased risk for other chromosome abnormalities involving 15q11-q13. © 1995 Wiley-Liss, Inc.