122例智力低下患儿染色体核型分析

目的探讨智力低下患儿染色体变化的有关特点和意义。方法染色体制备采用淋巴细胞培养或骨髓细胞短期培养法,应用G、C等显带技术,对122例患儿进行细胞遗传学分析。结果122例智力低下患儿,检出异常核型57例,异常率为46.72%。其中染色体数目异常50例,以21三体综合征为主(84.21%);染色体结构异常2例;复合异常5例。结论智力低下的病因复杂,遗传物质的改变是其中一个重要因素,开展染色体分析对于减少遗传病患儿出生,提高人口素质以及明确其病因和积极治疗都具有重要意义。     

郑州地区666例智力障碍儿童异常染色体核型分析

目的探讨666例智力障碍儿童异常染色体的核型分析。方法常规外周血淋巴细胞染色体检查。结果与结论1014例中共发现染色体正常（320—550条带阶段未见染色体异常）的350例,染色体异常666例,占全部受检病例的65．7％（666／1014）,其中各种类型的21三体综合征（Down’s）644例,占染色体异常核型的96．7％（644／666）,其中有1例47,XY,＋21,t（2;5）为世界首报核型。其余异常核型分别涉及到2、3、5、7、8、9、10、12、13、14、15、16、18、22号染色体共20例。表明引起儿童智力障碍染色体异常是重要原因,而Down’s综合征又是染色体异常中最主要的原因．达96．7％。     

兰州地区158例智力低下遗传咨询儿童染色体核型分析

目的探讨染色体异常在智力低下、发育落后、生长缓慢和发育异常的患儿中的临床意义。方法取患者外周血进行淋巴细胞培养,常规制片,G显带进行染色体核型分析。结果在158例先天性智力低下儿童中,发现染色体异常56例,异常检出率为35.443%;其中常染色体异常41例,占异常数的73.214%,性染色体异常核型4例,占异常数7.143%,染色体多态性11例,占异常数19.643%。结论先天性智力低下与染色体异常密切相关,对遗传咨询的患儿应进行染色体检查,及早明确病因,以免盲目诊治。     

宜昌地区158例遗传咨询患儿染色体异常核型分析

对临床诊断有精神运动发育迟缓、脑瘫、先天畸形、特殊面容、智力低下、身材矮小、外生殖器异常等858例患儿进行了外周血淋巴细胞染色体G显带检查,检出染色体异常核型158例。检出率为18.41%。其中常染色体数目异常110例,常染色体结构异常19例,性染色体数目异常18例,性染色体结构异常11例。检出异常核型尤以21三体为主。提示染色体异常与儿童智力低下及发育异常有密切关系,21三体综合征Down’s syndrome仍是最常见染色体病,有效控制及预防染色体病的发生对提高人口素质十分必要。     

271例儿童染色体异常核型分析及其与疾病关系

对临床诊断有精神运动发育迟缓、脑瘫、先天畸形、特殊面容、智力低下、身材矮小.、外生殖器异常等1125例患儿进行了外周血淋巴细胞染色体G显带检查,检出染色体异常核型271例.检出率为24.1%.其中常染色体数目异常197例,常染色体结构异常42例,性染色体数目异常17例,性染色体结构异常15例.检出异常核型尤以21三体为主.提示染色体异常与儿童智力低下及发育异常有密切关系,21三体综合征(Down's syndrome)仍是最常见染色体病,有效控制及预防染色体病的发生对提高人口素质十分必要.     

吉林地区80例遗传咨询儿童外周血异常染色体分析

本文采用外周血进行淋巴细胞培养，常规制片，Ｇ显带的方法发两全我异常染色体核型，其中２１三体综合征先天愚型）７５例，占异常染色体核型９３．７５％，分为２１三体型６８例，占９０．６７％，易位型４例，占５．３３％，嵌合型３例，占４％。本组各型比例与国内报道略有差异，可能与地区差异的局限性有关。先天性卵巢发育不全综合征３例，占３．７５％，染色体平衡易位１例，占１．２５％，３号染色体臂间倒位１例，占１．２５     

玉林地区智力低下儿童与染色体异常核型关系的探讨

目的为了解智力低下的儿童与染色体异常核型关系。方法对320例智力低下儿童采用外周血细胞培养法,G显带检测染色体核型。结果320例智力低下的儿童,发现染色体异常核型222例,异常检出率69．38％,其中,21-三体综合征215例（包括标准型21-三体综合征203例,易位型21-三体综合征9例,嵌合体型21-三体综合征3例）,检出率67．19％;平衡易位2例,检出率0．62％;其它结构异常5例,检出率1．25％。结论智力低下的儿童与染色体核型异常有密切关系,染色体异常核型以21-三体综合征为主。     

60例智力低下患儿的染色体核型分析

目的探讨智力低下(MR)患儿的细胞遗传学特点及意义。方法采用72h培养法制备外周血染色体,G显带技术进行染色体核型分析并照相。结果本研究60例MR患儿中检出异常染色体核型34例,检出率(56.7%)。结论说明染色体异常是导致MR的一个重要原因之一,对MR患儿进行染色体检查是非常必要的。     

广州地区198例先天智能发育不全儿童细胞遗传学研究

为了探索小儿先天智能发育不全与染色体异常之间的关系,我们对198例先天智能发育不全患儿的外周血淋巴细胞进行了细胞遗传学分析,发现69例异常核型,占受检人数的34.85％,其中21三体占异常核的86.96%,说明染色体异常是小儿先天智能发育不全的重要遗传因素。     

染色体异常核型14例

1对象与方法。1984年3月至2004年8月2562例在我室遗传咨询门诊就诊的患者，取外周血。淋巴细胞培养，常规制片．进行染色体核型检查．后经中国医学遗传中心鉴定而最后确诊14例异常核型国内外资料未见报道。其中男性6例，女性8例。平衡易位11例，二倍体与四倍体嵌合体1例，臂间倒位1例，平衡易位伴数目异常1例。患者或父母分别有自然流产或生育畸形、智力低下患儿史。其核型及临床表现见表1。     

Chromosomal copy number changes in patients with non-syndromic X linked mental retardation detected by array CGH

Several studies have shown that array based comparative genomic hybridisation (CGH) is a powerful tool for the detection of copy number changes in the genome of individuals with a congenital disorder. In this study, 40 patients with non‐specific X linked mental retardation were analysed with full coverage, X chromosomal, bacterial artificial chromosome arrays. Copy number changes were validated by multiplex ligation dependent probe amplification as a fast method to detect duplications and deletions in patient and control DNA. This approach has the capacity to detect copy number changes as small as 100 kb. We identified three causative duplications: one family with a 7 Mb duplication in Xp22.2 and two families with a 500 kb duplication in Xq28 encompassing the MECP2 gene. In addition, we detected four regions with copy number changes that were frequently identified in our group of patients and therefore most likely represent genomic polymorphisms. These results confirm the power of array CGH as a diagnostic tool, but also emphasise the necessity to perform proper validation experiments by an independent technique.     

1680例智力低下儿童的遗传咨询研究

1991年10月至1997年6月通过遗传咨询观察了智力低下（MR）儿童1680例,其中男性占53．3％,女性占46．7％;伴癫痫者占11．2％,伴脑瘫者占21％,第一胎占82．6％,轻度MR占73．8％,中度MR占22．9％,重度MR占3．3％,染色体核型异常检出率为14．6％．其中常染色体异常占73．1％,性染色体异常占26．9％,在病因探讨中,属于出生前因素占41．2％．出生时因素占26．5％,出生后因素占2．7％,原因不明占29．6％。     

智力低下儿童手部皮纹分析

为了探讨智力低下儿童的皮纹特征,我们将临床确诊为智力低下的69例患儿的手部皮纹进行了采集、分析。进一步证实了智力低下儿童手部皮纹确有一定的特征,主要表现为：总指嵴数（TFRC）、atd角、a-b嵴数、指端简单弓形纹、指端桡侧箕形纹、通贯掌褶纹的出现率增加,男性智力低下儿童大鱼际真实花纹出现率降低。结果表明,智力低下儿童手部皮纹的变化是客观存在的,它将为临床诊断智力低下提供客观依据。     

新疆地区132例低智儿童的染色体核型分析

目的对132例智力低下儿童进行染色体核型分析,探讨导致儿童智力损伤的可能因素。方法采用G-带分析和荧光原位杂交（FISH）技术,对132例智力低下的儿童进行染色体核型分析,结合儿童的相关临床特征,探讨导致儿童智力低下的常见因素。结果在132例核型分析样本中,检出核型异常患儿39例,包括21-三体综合征26例、22-三体综合征1例、X-脆性染色体3例、Klinefelter综合征3例、Turner综合征4例、4号环状染色体综合征和罗氏易位伴衍生染色体各1例。结论染色体异常是导致新疆儿童先天性智力低下的重要遗传学因素。     

133例智力低下患儿细胞遗传学研究

目的探讨智力低下患儿与染色体异常的关系。方法常规外周血染色体核型分析。结果 133例患儿中共检出染色体异常74例,异常检出率55.6%。其中常染色体数目异常62例,结构异常9例;性染色体数目异常2例,结构异常1例,结论染色体异常是导致儿童智力低下的重要原因,对此类患儿进行染色体核型分析很有必要。     

Application of metaphase HR-CGH and targeted Chromosomal Microarray Analyses to genomic characterization of 116 patients with mental retardation and dysmorphic features

Recent advances in molecular cytogenetics enable identification of small chromosomal aberrations that are undetectable by routine chromosome banding in 5-20% of patients with mental retardation/developmental delay (MR/DD) and dysmorphism. The aim of this study was to compare the clinical usefulness of two molecular cytogenetic techniques, metaphase high-resolution comparative genomic hybridization (HR-CGH) and targeted array CGH, also known as Chromosomal Microarray Analysis (CMA). A total of 116 patients with unexplained mild to severe MR and other features suggestive of a chromosomal abnormality with apparently normal or balanced karyotypes were analyzed using HR-CGH (43 patients) and/or CMA (91 patients). Metaphase HR-CGH detected seven interstitial deletions (16.3%). Rare deletions of chromosomes 16 (16p11.2p12.1) and 8 (8q21.11q21.2) were identified. Targeted CMA revealed copy-number changes in 19 of 91 patients (20.8%), among which 11 (11.8%) were clinically relevant, 6 (6.5%) were interpreted as polymorphic variants and 2 (2.1%) were of uncertain significance. The changes varied in size from 0.5 to 12.9 Mb. In summary, our results show that metaphase HR-CGH and array CGH techniques have become important components in cytogenetic diagnostics, particularly for detecting cryptic constitutional chromosome imbalances in patients with MR, in whom the underlying genetic defect is unknown. Additionally, application of both methods together increased the detection rates of genomic imbalances in the tested groups.     

Subtelomeric rearrangements detected in patients with idiopathic mental retardation

A screening for submicroscopic rearrangements was performed in 111 patients with idiopathic mental retardation (MR) using fluorescence in situ hybridization (FISH) probes from the subtelomeric regions of all chromosome arms. Ten cryptic rearrangements were found (9%): five de novo deletions; one unbalanced de novo translocation; three unbalanced inherited translocations; and one unbalanced recombinant chromosome, inherited from a parent with a pericentric inversion. In addition, 50 of the patients were screened for interstitial rearrangements with spectral karyotyping (SKY), but no aberrations were found. However, SKY detected the subtelomeric rearrangement in three of the four unbalanced translocations. Dysmorphic features were present in all patients with detected subtelomeric rearrangements.     

MECP2 mutation analysis in patients with mental retardation

Mutations in the methyl-CpG-binding protein 2 (MECP2) gene are known to underlie Rett' syndrome, the most common cause of mental retardation (MR) in girls. Since the original report, phenotypes resulting from MECP2 mutations have been shown to extend, for example, to several Rett variants, autism, atypical Angelman syndrome, and nonspecific MR. It was earlier proposed that MECP2 mutations might account for approximately 2% of the male cases with nonspecific MR. Thereby, the frequency of MECP2 mutations in the mentally retarded population would be comparable to that of Fragile-X syndrome. The aim of this study was to analyze well-characterized cases with MR and to clarify the role of the MECP2 gene in the etiology of MR and atypical Angelman syndrome. The coding sequence of the MECP2 gene was analyzed in a sample of 118 patients (103 males, 15 females) by direct sequencing. Two coding sequence variants, 602C > T (A201V) and 1189G > A (E397K), were identified. In addition, we identified four variants in the intronic or 3'UTR regions. None of these variants is likely to be causal. We conclude that the evidence across all the mutation screening studies implies that MECP2 mutations do not represent a major cause of nonspecific MR.     

High seroprevalence of Helicobacter pylori infection in non-institutionalised children with mental retardation

Eighty-four children with mental retardation (34 boys, 50 girls; age range 2-18 years, median 6 years) and 84 age- and gender-matched outpatient controls were studied. All children were living at home, had never stayed in an institution, and came from the same urban area. Seropositivity for Helicobacter pylori was found in 42 (50%) of 84 mentally retarded children and 16 (19%) of 84 controls (p < 0.01). Socio-economic factors did not differ between the two groups. The findings indicated that a higher prevalence of H. pylori infection occurs in children with mental retardation, regardless of whether they are institutionalised.