联合应用多种分子遗传学技术阐述染色体芯片结果中潜在的结构异常

目的探讨拷贝数变异中潜在的结构异常。方法通过联合应用常规核型分析及FISH等分子生物学技术对4例存在拷贝数变异的智能障碍合并多发畸形的患儿进行鉴定,明确其染色体结构异常;进而对2个家系进行产前诊断及随访。结果 4例患儿经染色体芯片检测发现存在拷贝数变异,分别为16pter缺失/19qter重复、18pter缺失/18qter重复、13 qter缺失和3 p 13-14缺失。联合核型分析及FISH检测明确患儿潜在的结构异常,分别为1例染色体末端不平衡易位der(16)t(16p;19q)、1例倒位重复缺失invdup18p/del 18q、1例涉及随体易位(13qs)及1例父源性平衡插入重组导致3p间隙性缺失或重复。其中2例为家族性平衡重组导致,1例未确定但存在再发风险,1例为新发改变。其中2个家系于孕中期进行产前诊断,并随访证实与产前诊断结果一致。结论染色体芯片发现单纯拷贝数变异者可能存在潜在的染色体结构异常,联合应用多种技术可以明确潜在的结构异常,并提供准确的再发风险评估,从而指导疾病的产前诊断。     

Y染色体拷贝数变异致性发育异常的临床和遗传学特点

目的探讨Y染色体拷贝数变异致性发育异常(DSD)患儿的临床表型和遗传学特点。方法回顾性分析郑州大学第一附属医院2018年1月至2022年9月收治的3例Y染色体拷贝数变异致DSD患儿的临床资料, 应用染色体核型分析、全外显子测序(WES)、低深度全基因组拷贝数变异测序(CNV-seq), 荧光原位杂交(FISH)和性腺组织病理活检技术对患儿进行临床分析和遗传学检测。结果 3例患儿就诊年龄分别为12、9、9岁, 均表现为身材矮小和性腺发育不良, 社会性别均为女。均为正常女童外阴, 例1伴脊柱侧弯, 余未见明显异常。3例患儿均报告为46, XY核型, WES未发现相关基因变异。CNV-seq确定例1为47, XYY, +Y(2.12), 例2为46, XY, +Y(1.6), 即Y染色体拷贝数增加。FISH最终确定2例患儿Yq11.2附近断裂后发生重组, 为携带拟双着丝粒Y染色体idic(Y)的嵌合体DSD。例1核型重新诠释为mos 47, X, idic(Y)(q11.23)×2[10]/46, X, idic(Y)(q11.23)[50], 例2为45, XO[6]/46, X, idi...     

染色体微阵列分析技术应用于筛查胎儿先天性心脏病的研究进展

先天性心脏病（congenital heart disease,CHD）是一种常见的出生缺陷,是由环境和遗传因素共同引起,其中遗传因素发挥着主要作用。G显带核型检测、荧光原位杂交,及染色体微阵列分析（CMA）技术是目前常见的基因诊断技术,近年来,CMA技术已逐渐成为产前诊断胎儿CHD的一线方法。CMA的主要优点之一是它能够精确定义不平衡区域,可明确诊断微缺失或微重复综合征,同时也可检测到大量的临床意义不明的拷贝数变异。在检测产前样本中总拷贝数变异时,拷贝数变异检测具有高可靠性、准确性和再现性的特点。但在许多情况下,拷贝数变异对CHD患儿心脏发育的影响尚不清楚。该文将以染色体微阵列分析技术为重点,对其在胎儿CHD的诊断意义及预后指导作一综述。     

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。     

混合性性腺发育不良伴外生殖器畸形临床及分子遗传学研究

目的 分析混合性性腺发育不良（mixed gonadal dysgenesis,MGD）伴外生殖器畸形患儿的临床特征及其与分子遗传学的相关性。方法 收集2002年1月至2014年12月因外生殖器畸形就诊于上海交通大学医学院附属瑞金医院儿内科5例患儿病例资料,其染色体为45,X/46,XY嵌合体或包含45,X/46,XY的其他嵌合体。分析其临床特征并进行相关辅助检查,采用多重连接依赖式探针扩增技术（multiplex ligation-dependent probe amplification,MLPA）检测外周血DNA中Y染色体微缺失情况及性发育过程相关基因拷贝数变化。结果 5例MGD患儿临床表型不一,其中3例为男性抚养,2例女性抚养。4例存在不同片段及数量的Y染色体微缺失,5例均未检测到WNT4、NR5A1、SOX9、Cxorf21的拷贝数异常。 结论 MGD临床表型谱广泛,外生殖器畸形严重程度不一。临床表型和外周血染色体核型嵌合比例之间无明显关联。Y染色体微缺失在MGD中的发生率很高,微缺失的范围大小可能和外生殖器的男性化程度正相关。     

染色体微阵列分析在先天性多发性畸形临床诊断中的应用

目的探讨染色体微阵列分析(CMA)在先天性多发畸形新生儿遗传病因学诊断中的应用价值。方法对100例多发畸形新生儿进行染色体G-显带核型分析和CMA分析。结果 100例患儿的临床表现以心血管系统畸形合并其他系统畸形最为多见,占69%。G-显带核型分析显示,21例患儿存在染色体异常,占21%。其中,常染色体数目异常9例,性染色体数目异常2例,常染色体结构异常10例。染色体核型正常的79例患儿经CMA分析基因拷贝数变异(CNVs)后,发现7例存在CNVs,4例为致病性CNVs,2例为未见明确致病性报道CNVs,1例为临床意义不明CNVs。结论 CMA具有分辨率高、覆盖度广的优势,可以从亚微观结构发现染色体缺失和重复,从而对先天性多发性畸形新生儿进行遗传病因学诊断。     

45，X/46，X，+mar男性患儿临床及遗传学分析

目的分析45,X/46,X,+mar男性患儿的临床及遗传学特征。方法回顾分析2例确诊45,X/46,X,+mar男性患儿的临床资料,并复习相关文献。结果2例男性患儿,年龄分别为10岁7个月和3岁1个月,均有矮小表现,且伴有性腺发育落后。例1合并精索静脉曲张,头颅磁共振成像示部分空蝶鞍,外周血染色体核型分析为45,X[31]/46,X,+mar[69],二代测序检测提示Y染色体短臂SRY基因拷贝数重复,长臂USP9Y基因整体缺失。例2外周血染色体核型分析也为45,X[5]/46,X,+mar[75],全基因组CNV检测提示染色体核型为46,XY,Y染色体AZFb+AZFc区域完全缺失。结论矮小症患儿应密切关注其外生殖器的形态及功能,必要时进行遗传学分析。     

21三体综合征46例染色体核型分析

目的分析21三体综合征（DS）患儿的染色体核型，为降低DS的风险提供产前诊断依据。方法对智力低下206例儿童进行详细的遗传咨询：遗传病史（有遗传病史进行系谱分析）、DS临床体征、父母的染色体及生育年龄情况、父母接触有害物质情况。行外周血淋巴细胞培养，行常规G显带核型分析。对气促、发绀、心脏杂音、心电图和胸片等可疑有先天性心脏病者，应用彩色多普勒超声心动图（CDFM）检查；DS 1例患儿有脑性瘫痪症状，行脑电图、头颅CT检查；经确诊为DS的患者，患者父母做染色体核型分析。结果确诊DS患者46例，其中21三体型42例（占92％）；易位型21三体2例（占4％）；嵌合型21三体2例（占4％）。DS并先天性心脏病16例（占35％）；并脑性瘫痪1例（占2％）。DS患儿46例父母的染色体核型均正常。结论开展细胞遗传学诊断分析，可精确检出DS，对DS高危人群未来的生育后代情况及预防DS患儿的出生提供科学依据。     

新发8p 重复伴缺失综合征患儿细胞分子遗传学研究

目的探讨8号染色体短臂倒位重复伴末端缺失[inv dup del(8p)]综合征的临床特征及细胞分子遗传学特点。方法回顾分析1例inv dup del(8p)综合征患儿的临床资料以及细胞分子遗传学分析资料。结果 6月龄女性患儿,具有发育迟缓、特殊面容、先天性心脏病及喉软化症等临床表现。外周血淋巴细胞染色体核型分析显示,患儿为46,XX,der(8)inv dup(8)(p21),del(8)(p23),父母均无异常;高通量测序染色体组拷贝数分析(CNV)精确定位拷贝数异常改变的染色体片段区域,检出患儿在8p23.3-p23.1(160 001-7 120 000)区域缺失6.96 Mb片段,在8p23.1-p21.1(12 560 001-27 940 000)区域,重复15.38 Mb片段;荧光定量PCR验证CNV显示在重复和缺失片段之间有一个5.4 Mb的拷贝数正常片段。结合临床表现及各检测结果确诊患儿为inv dup del(8p)综合征。结论结合临床特征、外周血染色体核型分析、CNV及荧光定量PCR技术可有效确诊inv dup del(8p)综合征。     

56例生长障碍患儿单核苷酸多态性基因芯片检测结果分析

目的探讨生长障碍患儿的分子遗传学基础。方法 2013年1月至12月采集56例生长障碍患儿的外周血并提取DNA,进行单核苷酸多态性基因芯片(SNP-array)检测。结果 56例患儿中12例(21.4%)有致病性拷贝数异常,性染色体异常6例,常染色体异常6例;4例(7.1%)有常规染色体核型分析无法检出的致病性微缺失或重复片段,其大小2.5 Mb。结论 SNP-array技术可作为生长障碍患儿遗传学诊断的有效方法。     

Fronto-nasal dysplasia and atrio-ventricular canal in a fetus with trisomy 18 identified by absent nasal bones during first trimester screening scan

Failed ultrasonographic visualization of nasal bones is associated with an increased risk of fetal malformations. Maternal ethnicity and chromosomal abnormalities influence the incidence and visualization rate of nasal bones. A case of absent nasal bones with fronto-nasal dysplasia and septated cystic hygroma identified at 13(+5) weeks' gestation in a trisomy 18 fetus is reported. The crown-rump length was 82 mm and the absent nasal bones were associated with micrognathia and a flattened face. The risks for trisomy 21 and 18 were subsequently calculated. The couple refused chorionic villus sampling. At 19 weeks' gestation a follow-up scan revealed, apart from the resolution of septated cystic hygroma, hypertelorism, a large interventricular septum defect with an atrio-ventricular canal and an abnormal A wave Doppler pulsation at the level of the ductus venosus. Bilateral choroid plexus cysts were additional ultrasound findings. At that time, an uneventful cordocentesis was performed showing a 47,XY(+18) karyotype. Termination of pregnancy was achieved and pathologic examination confirmed the ultrasonographically detected fetal malformations. When screening the fetal face for the presence or absence of nasal bones during the first trimester pregnancy scan the following points must be taken into consideration: (i) the ethnicity of the mother; (ii) if the nasal bones are absent, measurement of nuchal translucency and risk calculations for trisomy 21 and trisomy 18 should be performed; (iii) if the calculated risks are high, karyotyping should be recommended; and (iv) determine whether the absent nasal bones are an isolated or an associated finding and, in the latter case, discriminate between minor or major fetal malformations.     

Skeletal abnormalities in fetuses with Down's syndrome: a radiographic post-mortem study

Objective. To evaluate skeletal abnormalities on post-mortem radiographs of fetuses with Down's syndrome. Materials and methods. Biometrical and morphological criteria, which are used for US prenatal detection of trisomy 21, were assessed. Limb long bones, biparietal diameter (BPD)/occipito-frontal diameter (OFD) ratio, ossification of nasal bones and appearance of the middle phalanx of the fifth digit (P2) in 60 fetuses with Down's syndrome were analysed and compared with 82 normal fetuses matched for gestational age (GA) from 15 to 40 weeks' gestation (WG). Results. We observed reduced growth velocity of limb long bones during the third trimester in both groups, but the reduction was more pronounced in the trisomic group. Brachycephaly was found as early as 15 WG in Down's syndrome and continued throughout gestation (sensitivity 0.28, specificity 1). Ossification of the nasal bones, which can be detected in normal fetuses from 14 WG, was absent in one quarter of trisomic fetuses, regardless of GA. The middle phalanx of the fifth digit was evaluated by comparison with the distal phalanx (P3) of the same digit. We found that P2 was not ossified in 11/31 trisomic fetuses before 23 WG, and was either not ossified or hypoplastic in 17/29 cases after 24 WG (sensitivity 0.56, specificity 1). Conclusions. Three key skeletal signs were present in trisomic fetuses: brachycephaly, absence of nasal bone ossification, and hypoplasia of the middle phalanx of the fifth digit. All these signs are appropriate to prenatal US screening. When present, they fully justify determination of the fetal karyotype by amniocentesis. Received: 19 May 1998 Accepted: 19 February 1999     

Contribution of fetal MRI to the diagnosis of inner ear abnormalities: report of two cases

We report two cases of fetal inner ear abnormalities diagnosed by MRI. Cerebral MRI was performed on two fetuses, at 32 and 30 weeks gestation, following US that demonstrated multiple malformations suggestive of CHARGE syndrome in one fetus and ventriculomegaly and poor visibility of the posterior fossa in the other. MRI revealed vestibular hypoplasia and agenesis of the semicircular canals in one fetus and cystic cochleas, partial vermian agenesis and an occipital meningocele in the second fetus. Both pregnancies were terminated and there was good correlation between fetal MRI, ex utero CT and fetopathological findings. The inner ears should be carefully examined when performing fetal cerebral MRI because abnormalities of the inner ear may be associated with cerebral anomalies.     

Fetal outcome of trisomy 18 diagnosed after 22 weeks of gestation: Experience of 123 cases at a single perinatal center

To investigate the pregnancy outcome of the fetuses with trisomy 18, we studied 123 cases of trisomy 18 who were born at our hospital from 1993 to 2009. Among them, 95.9% were diagnosed with trisomy 18 prenatally. Prenatal ultrasound findings showed fetal growth restriction in 77.2%, polyhydramnios in 63.4% and congenital heart defects in 95.1%. For 18 cases, cesarean section (C‐section) was chosen, and for 75 cases, transvaginal delivery was chosen. Premature delivery occurred in 35.5%. Stillbirths occurred in 50 cases (40.7%). Fetal demise before onset of labor occurred in 30 cases and fetal demise during labor occurred in 20 cases which was 26.7% of vaginal deliveries. Among the 73 live‐born infants, the survival rate for 24 h, 1 week, 1 month and 1 year were 63%, 43%, 33% and 3%. The median survival time was 3.5 days. There was no significant difference between the survival time of C‐section and that of vaginal delivery. However, for the births involving breech presentation, the survival time of C‐section was significantly longer than that of vaginal delivery. When the fetus is diagnosed with trisomy 18, the parents have to make many choices. These findings constitute critical information in prenatal counseling to the couples whose fetuses have been found to have trisomy 18, especially when they choose palliative approaches in the perinatal management.     

Prenatal detection of microtia by MRI in a fetus with trisomy 22

Trisomy 22 is a rare chromosomal abnormality infrequently detected prenatally. External ear abnormalities, in particular microtia, are often associated with trisomy 22, but prenatal detection of microtia has not been reported in association with trisomy 22. We report a fetus with trisomy 22, with fetal MRI findings of microtia, craniofacial dysmorphism, and polygyria. Fetal MRI is a useful tool for auricular assessment and might have utility in the prenatal detection of chromosomal abnormalities, especially among fetuses with structural anomalies.     

Prenatal diagnosis of alpha- and beta-thalassaemias in Singapore--current status.

Prenatal diagnosis was performed in 31 pregnancies where the fetuses were at risk for either homozygous alpha(0) - or beta-thalassaemia. First-trimester prenatal diagnosis by DNA analysis using chorionic villi was carried out for 17 pregnancies at risk for homozygous alpha (0)-thalassaemia. The alpha-globin genes in fetal DNA were detected by gene mapping using restriction endonuclease mapping and hybridization with cloned alpha-globin probe. Homozygous alpha (0)-thalassaemia was detected in four fetuses and the results were subsequently confirmed by electrophoresis of the cord blood where only Hb Barts was detected. Prenatal diagnosis for beta-thalassaemia was carried out by globin chain biosynthesis using fetal blood at 18-20 weeks' gestation. Using carboxymethyl (CM) sepharose chromatography, homozygous beta-thalassaemia was predicted in six pregnancies, and one fetus carried Hb E-beta thalassaemia. The seven pregnancies were terminated and globin chain analysis using cord blood confirmed the prenatal diagnoses. The remaining seven fetuses were diagnosed as either normal or beta-thalassaemia carriers. Using DNA analysis and globin chain biosynthesis for prenatal diagnosis of homozygous alpha(0)- and beta-thalassaemia, a 100% correlation was achieved with fetuses predicted to possess the homozygous condition.     

The ultrasonographic assessment of the fetal thorax and fetal breathing movements in the prediction of pulmonary hypoplasia

Comparison was made of fetal breathing movements (FBM) and thoracic measurements in the prenatal diagnosis of pulmonary hypoplasia. In 20 pregnancies with oligohydramnios due to premature and prolonged rupture of the membranes (PROM) the presence or absence of FBM was assessed, the internal thoracic and cardiac circumferences were measured and the internal thoracic and lung areas calculated. All 5 infants with absent FBM died from pulmonary hypoplasia in the neonatal period and all 15 with FBM present survived. The internal thoracic circumference of 3 of the fetuses that developed pulmonary hypoplasia and 1 of those that did not were below the 2.5th centile of a reference range constructed from 76 normal pregnancies. Similarly, the lung areas were below the 2.5th centile of our reference range in 3 fetuses who developed pulmonary hypoplasia and 2 of those that survived. The absence of FBM was found to be the most accurate predictor of pulmonary hypoplasia in pregnancies complicated by oligohydramnios due to PROM.     

Prenatal Diagnosis of Oculocutaneous Albinism Type I: Review and Personal Experience

Oculocutaneous albinism type I (OCA I) comprises autosomal recessive syndromes of hypopigmentation and low vision, caused by the lack of tyrosinase activity. Affected families seek genetic counseling and prenatal diagnosis as preventive measures. Until recently, prenatal diagnosis of OCA I was achieved by histologic and electron microscopic examination of fetal skin biopsies. Lately, a molecular genetic approach has become possible by the identification of the two mutated copies of the TYR gene, coding the tyrosinase, in which over 60 mutations have been identified. We report here our experience in prenatal diagnosis of OCA I using the two strategies. Thirty-four prenatal tests were performed in fetuses at risk for OCA I. In 31 cases the diagnosis was made in fetal scalp biopsies using the histological approach. The microscopic observations revealed normal melanogenesis in 26 biopsies. Five albino fetuses were diagnosed by the demonstration of arrest of melanogenesis in early stages I and II. In three pregnancies, molecular genetic tests were performed on DNA extracted from amniocytes, using direct mutation analysis (in one), and complemented by linkage analysis (in two). One albino and two normally pigmented fetuses were diagnosed. The prenatal molecular genetic test can be applied to families when at least one mutation is diagnosed in the albino patient. The histological approach is applicable in all families at risk for OCA I.     

The Impact of Fetal Echocardiography

Fetal echocardiography has impacted the fetus with congenital heart disease in many important ways. Advances in fetal echocardiography have allowed for more accurate and earlier detection of cardiac abnormalities. In turn, the prenatal diagnosis of cardiac abnormalities has improved the care and outcome of selected fetuses with severe cardiac malformations or arrhythmias. Fetal echocardiography has improved the understanding of the development and evolution of congenital heart disease in utero, and it may serve a role in identifying candidates for prenatal intervention. The prenatal diagnosis of congenital heart disease has allowed for better counseling and preparation of families regarding the anticipated prenatal development of the fetus as well as the expected postnatal management plans and prognosis. This article reviews the impact of fetal echocardiography in these and other areas.     

Prenatal diagnosis of Holt-Oram syndrome: Role of 3-D ultrasonography

Holt-Oram syndrome (HOS) is an autosomal dominant disorder consisting of a congenital heart defect in combination with upper limb abnormalities. This report presents the ultrasonographic follow-up of a fetus at risk for this syndrome. An abnormal four-chamber view of the heart and slight shortening of the forearm were found by prenatal ultrasound performed at 16 weeks of gestation. At 25 weeks of gestation, detailed sonographic examination clearly revealed abnormalities in the upper limbs and heart of the fetus. At 39 weeks of gestation, spontaneous labor and delivery produced a female infant weighting 2940 g. Postnatal examination of the infant confirmed the prenatal sonographic findings. 3-D ultrasound has an important role in prenatal diagnosis of HOS, which is essential for proper genetic counseling.