Pallister-Killian综合征1例临床及细胞分子遗传学分析

目的探讨Pallister-Killian综合征(PKS)的细胞分子遗传学特点。方法采集患儿外周血标本进行G显带染色体核型分析,单核苷酸多态性-微阵列芯片(SNP array)技术鉴定异常片段来源,运用荧光原位杂交(FISH)技术加以确认。结果女性患儿,8月龄,因精神运动发育迟缓就诊。出生后有喂养困难、肌张力低下、面容异常、后发际线低、足部畸形、双耳听力未过关等临床表现。外周血染色体G显带核型为mos 47,XX,+mar[18]/46,XX[82];芯片分析结果发现患儿12号染色体短臂嵌合重复,提示为12 p四体嵌合体;FISH检测显示有48%的细胞有4个12 p信号。结论根据临床表现,常规外周血染色体核型分析结合SNP-array及FISH检测诊断PKS。     

新生儿细胞遗传学检测357例结果分析

目的分析怀疑染色体异常新生儿的细胞遗传学检测结果,为优生优育提供科学依据。方法选择2010年4月至2011年10月在浙江大学医学院附属儿童医院进行细胞遗传学检查的新生儿,分析不同送检原因异常核型检出率及异常核型分布情况。细胞遗传学检查方法：常规外周血淋巴细胞培养,制备染色体G显带标本,分析核型。结果研究期间共送检怀疑染色体异常新生儿标本357例,染色体异常检出率24．93％（89／357）,涉及异常核型25种。检出率排名前三位的送检原因为可疑先天愚型、先天性心脏病及泌尿生殖系统畸形。检出21三体综合征58例,占染色体异常的65．17％。结论我院新生儿染色体核型异常检出率高,检出率差异与送检原因有关。21三体综合征是新生儿时期最常见的染色体异常。     

22q11.2微缺失综合征的分子诊断及缺失范围检测

目的 分别采用多重连接探针扩增技术(MLPA)与荧光原位杂交技术(FISH)对22q1 1.2微缺失综合征外周血标本患者基因缺失/重复突变的类型及变异范围进行检测,分析在22q11.2微缺失综合征诊断中二者联合应用的诊断价值.方法 采集1例仅心脏异常患儿及其父母外周血,取200 μL外周血提取DNA后采用MLPA技术对患儿及其父母的染色体22q11.2缺失的范围进行检测,取外周血1 mL进行培养,采用DiGeorge/VCFS N25(D22S75)的FISH探针对培养后的中期淋巴细胞进行杂交.结果 患儿淋巴细胞分裂中期细胞应用FISH技术检测结果为22号染色体上的DiGeorge/VCFS N25(D22S75)区杂合性缺失;MLPA验证结果显示患儿与22q11.2微缺失综合征相关的6个探针对应的片段大小位置在3100的电泳图上荧光峰值相比健康对照明显出现减半,其父母亲均在正常范围.患儿的临床表现仅有先天性心脏病,无其他异常,与其基因缺失片段长度(2.0 Mb)极不相称.结论 联合应用FISH和MLPA检测22q11.2微缺失综合征,可以明显提高诊断的准确性.22q11.2微缺失综合征的临床表现与基因缺失片段的长度无相关性.     

15q11.2-13.2微重复四倍体综合征1例并文献复习

目的 采用分子遗传学技术分析1例常规染色体核型拟诊为21/22三体的发育迟缓伴孤独症患儿,明确遗传学诊断。方法 收集患儿及其父母的外周血标本,常规提取基因组DNA,应用高分辨染色体核型分析（400-550带）检测患儿及其父母的染色体数目及结构,微阵列比较基因组杂交技术(array-CGH)筛查患儿的全基因组拷贝数变异,以荧光原位杂交技术（FISH）对异常的基因拷贝进行染色体精确定位和定量。结果 女,2岁,发育迟缓伴孤独症样表现。外侧眼角下垂、内眦赘皮。常规染色体核型检查（320带）分别为47,XX,+22和47,XX,+21。高分辨染色体核型分析显示,该患儿携带额外标记染色体（SMC）,核型为47,XX,+mar dn,尚不能确定是否为21/22三体携带者,患儿父亲高分辨率核型染色体分析提示为46,XY,母亲为46,XX,提示患儿携带SMC为新生突变。array-CGH检测显示15q11.2-13.2区域微重复（chr15:22684529-30730543,8.0 Mb,hg19）。FISH验证该SMC来源于15号染色体,由15q11.2-13.2区域二倍体及双着丝粒组成。患儿最终诊断为15q11.2-13.2微重复四倍体综合征。复习文献报道的15q11.2-13.2拷贝数增加病例的临床表型,微重复四倍体综合征的主要表型有智力低下/发育迟缓（100％）、肌张力低下（92.9％）、孤独症/孤独症样表现（71.4％）和癫痫（61.5％）等。结论 15q11.2-13.2微重复四倍体综合征是患儿发生精神发育迟滞伴孤独症的遗传学基础,array-CGH能够快速、准确地检测基因组的微小失衡。     

4例Williams-Beuren综合征家系遗传学诊断与产前诊断

Williams-Beuren综合征是一类常见的染色体微缺失综合征,早期诊断及干预对患儿及其家庭十分重要。本研究应用染色体核型分析技术(G显带),多重连接依赖探针扩增技术(MLPA)及微阵列比较基因组杂交技术(array-CGH)对4个家系中1例超声异常的胎儿及3例发育异常患儿行染色体核型和基因组DNA分析,为这4个家庭的再生育提供指导,为产前诊断提供依据。研究结果发现1例产前超声异常孕妇羊水及3例发育异常患儿外周血MLPA分析提示染色体7q11.23区域ELN基因探针信号降低,array-CGH检测提示染色体7q11.23区域杂合缺失。4个家系中母亲再次妊娠时取羊水细胞标本行上述检测均未发现异常。研究结果提示MLPA技术及array-CGH技术能够快速、准确地诊断Williams-Beuren综合征,为临床提供更好的遗传咨询服务。     

伴GATA1变异的非唐氏综合征急性巨核细胞白血病2例并文献复习

目的探讨GATA1基因变异致急性巨核细胞白血病(AMKL)的临床特征。方法分析2例GATA1基因变异致AMKL的非唐氏综合征患儿的临床资料,并复习相关文献。结果例1为2岁女性AMKL患儿,无特殊面容及发育迟缓;病初骨髓染色体核型示50,XX,+8,+10,+21,+21[7]/46,XX[13];基因检测示GATA1基因变异c.52dupT;经诱导化疗骨髓缓解后复查外周血染色体示46,XX;目前无病生存。例2为1岁男性AMKL患儿,无特殊面容;病初骨髓染色体核型示47,XY,+21[10]/46,XY[10];基因检测示GATA1变异;经化疗骨髓缓解后复查染色体示46,XY;目前持续缓解中。结论提示在非唐氏综合征儿童罹患AMKL时需重视GATA1基因变异的检测。     

12p三体新生儿1例临床及细胞分子遗传学分析

目的探讨12p三体新生儿的临床及细胞分子遗传学特点。方法回顾1例经外周血行淋巴细胞常规G显带染色体核型分析,高通量测序染色体组拷贝数分析(CNV)并经淋巴细胞间期荧光原位杂交(FISH)技术确认的12p三体新生儿的临床资料。结果患儿外周血染色体核型为47,XX,+mar,父母染色体核型均正常;CNV检出患儿12p13.33-p11.1(160 001～34 860 000)区域重复,片段大小为34.7 Mb;外周血淋巴细胞间期FISH显示患儿所有间期细胞核12号染色体短臂均存在3个信号,无嵌合体存在。确诊为12p三体。结论结合临床特征、外周血染色体核型分析、CNV及FISH技术可有效确诊12p三体。     

21三体综合征的诊断与干预研究

目的在细胞、细胞分子和分子水平对2l三体综合征(Downsyndrome，DS)进行诊断和干预。方法采用染色体显带、荧光原位杂交(FISH)、多聚酶链反应(PCR)技术，从外周血淋巴细胞、羊水细胞进行DS的诊断、产前诊断和干预。结果在遗传咨询确诊的446例患者中，21三体型、嵌合型、易位型分别占85．43％、6．05％、8．52％。对252例适应症对象进行改良羊水细胞培养产前诊断，取得满意的成功率，并检出DS胎儿3例。10例DS患儿外周血FISH分析，含3个杂交点细胞占90％，含2个杂交点者为10％。20例DS患儿外周血PCR分析，19例(占95％)在3个位点显示三条带。FISH和PCR的阳性结果与细胞遗传学的检测相一致。结论开展以传统细胞遗传学诊断与产前诊断，结合FISH和PCR技术共用，可最大限度地检出DS。     

2064例细胞遗传学分析临床与优生意义

为了解国内主要异常染色体核型的分布情况，给优生干预提供科学的依据，对2064例患者进行常规接种、培养并制备外周血淋巴细胞染色体G显带标本，必要时进行C带和高分辨G显带分析。结果显示，2064例患者中，染色体异常457例，异常检出率为22．1％，涉及异常核型80余种。染色体异常中常染色体异常263例，性染色体异常194例；染色体数目异常315例，结构异常116例，性反转26例。提示染色体核型分析是诊断染色体病、检出携带者以及进行产前诊断的主要方法；21-三体综合征和Turner综合征是临床最常见的染色体异常，其染色体核型复杂多样。     

5q14.3微缺失综合征导致婴儿痉挛症一家系的临床及遗传学研究

目的 分析婴儿痉挛症患儿的临床特征,并对患儿及其父母进行遗传学检测.方法 分析2014年3月接诊的1例婴儿痉挛症患儿面部特征、体格和智力发育状况.实验室检查采用常规G显带分析患儿及父母外周血染色体核型,单核苷酸多态性(SNP)基因芯片技术检测染色体微小改变,荧光原位杂交技术(FISH)验证结果,并对其父母染色体中期分裂象进行FISH检测.结果 患儿女,7岁,语言、运动、语言发育严重迟滞,生后4个月出现癫痫发作,临床诊断为“婴儿痉挛症”.体检见消瘦,面容特殊,存在刻板样不自主动作.头颅CT平扫提示“硬膜下积液”.脑电图检查提示:痫样放电频繁;高度失律.患儿及其父母常规染色体核型分析(400条带)均显示为正常核型.SNP微阵列技术检测显示该患儿染色体5q14.3区段微缺失,缺失片段为2.03 Mb,分子核型为arr5q14.3(87 538 430 ～ 89 565 757)× 1,该区段包含MEF2C基因.选择区域特异性RP11-293 L20探针,应用FISH技术对芯片结果进行验证,确认患儿5q14.3区域存在杂合缺失.父母染色体核型正常,无5q14.3区域缺失,无插入突变.结论 患儿染色体5q14.3区段发生缺失为婴儿痉挛症的病因.患儿为新发生的5q14.3微缺失综合征,父母再次生育时,建议选择SNP芯片技术进行产前诊断.     

Phenotypic heterogeneity and parental origin of extra chromosome 21 in Down syndrome

We compared the frequency of phenotypic features of 40 children with Down syndrome between individuals with a maternally or paternally derived extra chromosome 21, using quantitative FISH for comparing heteromorphisms of the nucleolar organizing region. Parental origin was determined in 90% of families. Hypotonia and craniofacial abnormalities were present in 90% or more individuals, irrespective of parental origin of chromosome 21. Congenital heart defects were more frequent in cases with a maternally derived extra chromosome 21. Imprinted gene(s) may contribute to the development of congenital heart defects in Down syndrome.     

Monozygotic twin discordant for Down syndrome: mos 47,XX,+21/46,XX and 46,XX

Monozygotic twins, developed from a single zygote, are almost identical in clinical phenotype and concordant karyotypes. Monozygotic twins with discordant karyotypes are thought to be quite rare. Here, we report monochorionic-diamniotic twins discordant for Down syndrome. On findings of prenatal ultrasonography, nuchal translucency thickness was different between twins, and suggested that one of the twins was at high risk for having chromosomal abnormalities including Down syndrome. The twins were monochorionic-diamniotic; therefore, chorionic villi sampling of the common placenta was performed. The karyotype of the chorionic villi cells was 46,XX, and pregnancy was maintained. After delivery, dysmorphic clinical features suggesting Down syndrome were found in one of the twins, while the other twin showed a morphologically normal appearance. Karyotypes of peripheral blood leukocytes were repeatedly normal in the dysmorphic twin; however, the karyotype of skin fibroblasts from the dysmorphic twin indicated Down syndrome mosaicism; 47,XX,+21[99]/46,XX[2]. The karyotype of skin fibroblasts from the morphologically normal twin was 46,XX. Monozygosity of the twins was confirmed by a short tandem repeat analysis using 16 polymorphic markers. A mitotic nondisjunction followed by the twinning would explain the discordant karyotypes between monozygotic twins.     

Acquired X-chromosome aneuploidy in children with acute lymphoblastic leukemia

BACKGROUND: A cytogenetic study of 75 consecutive children with ALL revealed a normal karyotype, a low hyperdiploid karyotype (including 47-50 chromosomes), and a high hyperdiploid karyotype (including > 50 chromosomes) in 10, 12, and 33 patients, respectively. An acquired extra X-chromosome was detected at diagnosis by conventional cytogenetics in 29 (88%) of 33 children with a high hyperdiploid karyotype and in 4 (33%) of 12 children with a low hyperdiploid karyotype. X-chromosome aneuploidy was retrospectively studied by fluorescence in situ hybridization (FISH) in eight and 20 patients with a normal and a hyperdiploid karyotype, respectively. PROCEDURE: A classical cytogenetic study was performed according to standard methods. FISH with the centromeric probe specific to X-chromosome was used to study interphase cells of bone marrow or blood samples. RESULTS: An extra X-chromosome was found by FISH in all 13 patients with a high hyperdiploid or tetraploid, in 6 of 7 patients with a low hyperdiploid, and in none with a normal karyotype. Two children with a normal karyotype displayed monosomy X. Altogether, 57.3% of newly diagnosed children displayed X-chromosome aneuploidy. CONCLUSIONS: Out study indicates that X-chromosome aneuploidy may be the most common chromosome abnormality in childhood ALL. It can be detected in nearly all children with a high hyperdiploid karyotype and up to one-half of the patients with a low hyperdiploid karyotype. FISH with an X-chromosome centromeric probe is a rapid and simple tool to detect an abnormal clone at diagnosis in the majority of children with ALL and is useful in confirming remission in these patients.     

Antitissue transglutaminase and antithyroid autoantibodies in children with Down syndrome and celiac disease

OBJECTIVES: We measured circulating autoantibodies and evaluated the potential of circulating antitissue transglutaminase (tTG) antibodies to determine the presence of celiac disease (CD) in children with Down syndrome. METHODS: An ELISA based on recombinant human tTG was used to measure the levels of immunoglobulin A and immunoglobulin G antibodies in serum samples from 72 children with Down syndrome, 52 children with biopsy-verified CD, 21 disease controls with a normal small intestinal mucosa and 23 healthy controls. Of the 72 Down syndrome children, 11 under-went a small intestinal biopsy. RESULTS: Four of 72 children with Down syndrome were diagnosed as having CD and three of them had serum levels of immunoglobulin A tTG antibodies greater than 6 U/mL (668, 147 and 7 U/mL). One Down syndrome child with biopsyproven CD had normal levels of immunoglobulin A tTG. Two Down syndrome children had increased levels of immunoglobulin A tTG (13 and 7 U/mL) but none of these children had an intestinal biopsy performed. Of the 52 CD subjects (median 664 U/mL) one was negative for immunoglobulin A tTG (5 U/mL) and all healthy controls (median 1.2 U/mL) and disease controls (median 0.9 U/mL) had immunoglobulin A tTG antibody levels less than 6 U/mL. Two of four Down syndrome children with CD and 36 of 52 celiac children had increased serum levels of immunoglobulin G tTG antibodies. There was no correlation between the serum levels of tTG and antithyroid autoantibodies. CONCLUSIONS: Although the diagnosis of CD depends on histologic evaluation of intestinal biopsies, detection of anti-tTG antibodies provides a useful complementary diagnostic method for CD in children with Down syndrome.     

Karyotype evolution in a patient with down syndrome and acute leukemia following a congenital leukemoid reaction

We report the serial cytogenetic study of a patient with Down syndrome who experienced a congenital leukemoid reaction, underwent a spontaneous remission within four months, and subsequently developed acute myeloid leukemia at 16 months. A blood chromosome study to rule out Down syndrome performed at age 24 days, during the leukemoid reaction, revealed a 47,XX,+21 karyotype. The diagnosis of acute leukemia was made at 16 months, at which time a chromosome study, on bone marrow, was performed. This analysis revealed a clonal karyotype of 47,XX,+21,-22,+der (22)t(1;22)(q21;q13) in all but one cell studied. The single apparently nonclonal cell showed a karyotype of 49,XX,+12,-13,-19, +der(19)t(19;?)(q11;?)x2,+21,+22. A third chromosome study at 19 months indicated the original leukemic clone with t(1;22) (q21;q13) had been replaced by the clone represented by the single cell with 49 chromosomes seen in the previous chromosome study. This case of an infant with Down syndrome and acute leukemia illustrated rapid evolution and a transitory nature to clonal chromosome aberrations while retaining AML morphology and course. © 1994 Wiley-Liss, Inc.     

Limitations of G-banding Karyotype Analysis with Peripheral Lymphocytes in Diagnosing Mixed Gonadal Dysgenesis

Mixed gonadal dysgenesis (MGD) is an abnormal sexual differentiation syndrome usually presenting with ambiguous genitalia. Karyotype analysis is one of the essential components in the diagnosis of MGD and is conventionally done with peripheral lymphocytes by the G-banding technique. It is speculated that this conventional karyotype analysis has limitations since there are often difference in gonadal tissue analysis. Here we present four cases of MGD, in which karyotype analysis were performed by peripheral lymphocytes fluorescence in situ hybridization (FISH), gonad fibroblasts FISH and gonad fibroblasts G-banding technique, in addition to the conventional peripheral lymphocytes G-banding technique. In Case 1, the percentage of the 45,X cell line in lymphocytes decreased after birth and detection of mosaicism could only be done by karyotype of gonads at 7 mo of age. In Case 2, FISH analysis with peripheral lymphocytes was more useful for detecting low frequency mosaicism. In all cases, phenotype of gonads and external genitalia were more consistent with karyotype of gonads than that of the peripheral lymphocytes G-banding technique. In conclusion, conventional G-banding karyotype analysis with peripheral lymphocytes has limitations in the diagnosis and evaluation of MGD. Karyotype analysis by FISH or by using gonads is useful for diagnosing MGD and understanding of the phenotype of gonadal tissue.     

Behavior in children with Down syndrome

Objective  To highlight the differences in behaviors in children with diagnosis of down syndrome. Method  Eight children with Down syndrome who displayed autistic features were compared with eight Down syndrome children without autistic features. These children were randomly selected and were matched for age and level of retardation. Standardized Psychological tests were administered to tap the behavioral differences. Mann-Whitney U test was used for significance of difference between both the groups. Results  Down syndrome children without Autism Spectrum Disorder had better communication and socialization skills than children with Down syndrome with Autism Spectrum Disorder. Down syndrome children with Autism Spectrum Disorder displayed more restricted repetitive and stereotyped patterns of behaviors, interests and activities. Conclusion  Our findings indicate that Autism Spectrum Disorder manifests as a distinct behavioral phenomenon in Down syndrome. Hence it is important for professionals to consider the possibility of a dual diagnosis which will entitle the child to a more specialized and effective educational and intervention services.