一种筛查中国人遗传性耳聋和氨基糖苷耳毒性易感人群的分子遗传学方法

Objective: To develop a molecular screening test for genetic defects on hearing loss related genes has significant impacts on early identification of hereditary hearing loss and genetic susceptibility to aminoglycoside ototoxicity. Early identification of pre-lingual hearing loss is very important for patient's language development, academic achievement, and social skill. Two common mutations, the 235delC in GJB2 gene and the mutation A1555G in mitochondrial DNA, are included in the newly developed screening panel for Chinese population. Methods: A molecular genetic assay, based on fluorescent labeled multiplex PCR and automatic DNA fragment analyzing techniques, was developed to detect both mutations simultaneously. Results: This assay was able to detect both mutations from patient's samples, and pooled DNA tests, as well as suitable to detect mutation from the DNA extracted from dried blood spot and buccal swab. Conclusion: This assay could be a useful tool for newborn screening and carrier screening for the hereditary hearing loss for the Chinese population.

SMN基因缺失多重连接探针扩增法检测和识别脊柱肌肉萎缩症的纯合型或杂合型SMN基因缺失

Objective: Spinal muscular atrophy(SMA), an autosomal recessive neuromuscular degeneration of the anterior horn cells of the spinal cord and brain stem, results in one of the most common diseases with muscle fatigue and atrophy. Most SMA cases including all the types are due to the homozygous deletion of at least exon 7 within the survival motor neuron 1 (SMN-1) gene. Although a "golden standard" assay (PCR with mismatch primer followed by enzyme digestion) is very reliable for the identification of homozygous SMN-1 deletion, the carrier detection of heterozygous SMN-1 deletion remains a challenge. Methods: Some PCR-based gene dosage assays or multiplex PCR allow for the determination of the copy number of SMN-1 gene to identify heterozygous deletion, but these procedures are often time consuming and available on a limited clinical basis. Recently developed MLPA (multiplex ligation-dependent probe amplification) is an efficient procedure that can accurately analyze relative quantification to establish the copy number of the SMN gene. We performed a validation for simultaneous detection of homozygous SMN-1 deletions of SMA patients and heterozygous SMN-1 deletions of SMA carriers in a simple assay using a MLPA-SMA assay specific reagent. Results: Six out of 20 patients with SMA were found to have homozygous SMN-1 deletion, confirmed by the PCR/digestion assay. All 4 parents of the children with SMA had heterozygous SMN-1 deletion, confirmed by an independent relative quantitative analysis. Conclusion: MLPA provides a simple, rapid and accurate method of simultaneously detecting homozygous deletions and heterozygous deletions in a single assay for both SMN-1 and SMN-2 genes.

湖南省106 224例新生儿先天性甲状腺功能减低症筛查

目的:早期诊断先天性甲状腺功能减退症(congenital hypothyroidism,CH)患儿,预防智力低下儿的发生.方法:采用时间分辨荧光免疫法测定促甲状腺素(thyroid-stimulating hormone,TSH)浓度,如果TSH筛查呈阳性,则使用化学发光免疫法(chemiluminescent immunoassay,CLIA)测定血清TSH、游离三碘甲状腺原氨酸(free triiodothyronine,FT3)、游离四碘甲状腺原氨酸(free thyroxin,FT4),并结合临床确诊.结果:湖南省1997年4月至2003年12月106 224份标本中共检出CH患儿68例,检出率1/1 562,明显高于全国平均水平(1/3 009).结论:(1)新生儿筛查是早期诊治CH患儿,预防CH发生智力低下的关键;(2)湖南为CH高发地区;(3)检出率与科学技术的发展呈相关性,累加检出率能更真实地反映发病率;(4)选择适当切值有助于防止漏筛.

应用多重连接探针扩增法简便高效检测Prader-Willi综合征的基因缺失

Objective: Prader-Willi syndrome (PWS) is characterized by severe hypotonia and feeding difficulties in early infancy, followed by excessive eating and gradual development of morbid obesity in later infancy or early childhood. Patients with PWS are often too young to manifest sufficient features or have atypical findings, making genetic testing important to confirm the diagnosis of PWS. Approximately 99% of patients with PWS have a diagnostic abnormality in the parent-specific methylation imprint within the Prader-Willi critical region (PWCR) at chromosome 15q11.2-q12. Of them, 70% have a paternal deletion; 25% have a maternal uniparental disomy (UPD); and <5% have a mutation in the imprinting center. Methods: Current techniques can identify a diagnostic abnormality, such as paternal deletion or maternal UPD for most of patients with PWS, but they are labor-intensive and cost-expensive. Multiplex ligation-dependent probe amplification (MLPA) is a novel, simple, and cost-effective technique for analysis of relative quantification in a single assay, which has recently been applied for the detection of genomic deletions, duplications, and amplifications in a variety of genes. Results: Six out of 20 patients referred for genetic diagnosis of PWS were found to have a deletion by MLPA, confirmed by FISH and DNA methylation analysis with 100% concordance. Conclusion: MLPA's high sensitivity and specificity for deletion detection is the same as FISH or Southern blot based analysis. Additional collaborative effort for developing and validating the complete MLPA-PWS assay, for not only detecting deletion but also identifying methylation abnormality, is on going.

血清生化标记物结合胎儿颈部半透明膜厚度产前筛查胎儿染色体异常

目的:探讨孕早期胎儿染色体异常的产前筛查方案.方法: 采用时间分辨荧光免疫法(TRFIA)对孕11～14周的2 739例孕妇血清中的人绒毛促性腺激素β亚单位(β-hCG)、妊娠相关血浆蛋白A(PAPP-A)进行检测,同时利用腹式或阴道B型超声波测量胎儿颈部半透明膜(NT)厚度,筛查出22例染色体异常胎儿(通过羊水细胞染色体核型分析明确诊断),比较分析22例染色体异常胎儿与870例对照组三种标记物水平.结果: 病例组NT和β-hCG值明显较对照组高,PAPP-A值明显比对照组低,差异有统计学意义,三项指标联合筛查,胎儿染色体异常检出率为91.67%,假阳性率为11.16%. 结论: 孕早期NT+β-hCG+PAPP-A三联筛查方案对孕早期产前筛查胎儿染色体异常有较好的实用价值.

新生儿EPHX1和GSTT1基因多态性与低出生体重的关系

目的:探讨微粒体环氧化物水解酶基因(microsomal epoxide hydrolase gene,EPHX1)139位点多态性和谷胱甘肽转硫酶theta1基因(the glutathione S-transferase theta1 gene,GSTT1)多态性对新生儿低出生体重的影响.方法:采用病例对照调查方法,使用统一设计的调查问卷,由经过培训的调查员于1998年至1999年在安徽省安庆市各县级医院对入院分娩孕妇及其单胎、活产的低出生体重儿和正常出生体重的对照新生儿进行调查,共得到246个母亲-新生儿对,其中低出生体重组73对, 正常出生体重对照组173对,用PCR-RFLP方法确定基因型.结果:EPHX1 His139His纯合子基因型与His139Arg杂合子基因/Arg139Arg纯合子基因型比较, GSTT1缺失基因型与存在基因型比较,多因素Logistic回归模型在经混杂因素(母亲年龄、文化程度、生育史、新生儿性别、孕周)调整前后,均未见导致低出生体重的危险性有显著性增加.进一步分析EPHX1139位点多态性和GSTT1位点多态性之间对低出生体重的影响,结果显示GSTT1缺失基因型和EPHX1His139His纯合子基因型之间有明显联合作用,导致低出生体重的危险因素增加(OR＝3.46, P=0.035).结论:基因EPHX1 139位点多态性和GSTT1位点多态性对低出生体重的影响有明显联合作用.

同步多色荧光原位杂交技术的建立及临床应用

目的:建立同步多色荧光原位杂交技术在外周血、羊水及单个胚胎细胞及骨髓细胞等样本中的实验方法,探索其在细胞遗传学、产前诊断、胚胎种植前诊断以及在血液病中的应用. 方法: 取外周血淋巴细胞、羊水细胞和不适于胚胎移植及冷藏的受精胚胎细胞、骨髓细胞分别制片,用相应的荧光标记的探针进行原位杂交,荧光显微镜取图分析. 结果:建立获得稳定可行的各类标本的实验方法. 结论:应用多色荧光原位杂交技术可对染色体进行快速准确的诊断,并可应用于产前诊断和胚胎种植前诊断及血液病的诊断.

先天性心脏病核心家庭血清同型半胱氨酸水平及相关基因多态性研究

目的:了解MTHFR C677T、MS A2756G、MTHFD G1958A和CBS 844 ins68bp位点在中国北方正常人群中的基因型分布,并评价单一或复合位点基因变异与叶酸、维生素B12、同型半胱氨酸(Hcy)水平及先天性心胖病(CHD)的关系.方法:选择辽宁省192例CHD患者及其父母作为病例组,同一地区年龄、性别匹配的124名正常人及其父母作为对照组,采用PCR-RFLP方法检测其基因型,放射免疫法和荧光偏振免疫法测定血清叶酸、维生素B12和Hcy水平,比较两组差异.结果:中国北方正常人群中,这四个位点的突变等位基因频率分别为MTHFR 51.18%, MS 7.58%, MTHFD 24.32%, CBS插入频率 2.36%;CBS 844 ins68bp位点杂合型频率病例组明显高于对照组(子代为12.57% 和 2.97%, 父亲为10.88% 和 3.09%,母亲为11.54% 和 1.02%),子代的OR值为4.70 (95% CI 1.34～25.15),父亲的OR值为3.83 (95% CI 1.05～20.98),母亲的OR值为12.65 (95% CI 1.92～532.47),其他三个位点两组差异无统计学意义;MTHFR、CBS和MTHFD三个位点联合基因变异的母亲、MTHFR 和 CBS两个位点联合基因变异的母亲(OR=8.44,95%CI:1.23～362.26)、MTHFD 和 CBS两个位点联合基因变异的母亲在病例组中所占的比例明显高于对照组;病例组父亲和母亲的血清叶酸水平明显高于对照组;病例组母亲的血清Hcy水平高于对照组,但差异无统计学意义;MTHFR 和 MTHFD两个位点为纯合型者的血清叶酸和维生素B12水平轻微下降,而血清Hcy水平轻微上升;联合基因变异使血清叶酸、维生素B12和Hcy水平出现下降趋势.结论:这四个位点的基因多态性存在着种族和地区差异,CBS 844 ins68bp位点突变可能是CHD发生的一个危险因素,亲代(尤其是母亲)的插入突变可使其后代发生CHD的危险性升高.

PAX6基因突变能够引起人脑结构异常

目的:研究PAX6基因突变与脑结构异常的关系.方法:应用核磁共振成像技术,对一个由PAX6 c1080C→T突变引起无虹膜的家系中18名患者和6名正常人进行脑结构扫描.结果:该家系大部分PAX6基因突变患者表现出不同程度的脑质退化变性、胼胝体变薄萎缩和嗅球萎缩等脑结构的异常,其中有一例病人还表现出Chiari 畸形的影像学特征.结论:进一步证实了PAX6基因突变能够引起人脑结构异常.

细胞标志蛋白CK7,Vim和P53在子宫内膜癌不同亚型发生机制中的作用

目的:检测细胞标志蛋白及P53在子宫内膜癌细胞的表达,探讨它们参与不同亚型子宫内膜癌发病的可能机制,分析其与肿瘤生物学行为的关系.方法:采用免疫组织化学法检测131例子宫内膜癌患者不同亚型、不同临床分期及不同分化程度的子宫内膜细胞中CK7,Vim及P53的表达.结果:CK7及Vim的表达分别与P53的表达存在正相关性.内膜样腺癌细胞中CK7表达高于其他类型,而Vim及P53的表达降低.Vim的表达与临床分期呈正相关;Vim及P53的表达阳性率随细胞分化级别上升而增加,具有相关性.结论:CK7、Vim、P53的编码基因可能通过转录水平的相互调控机制参与不同亚型子宫内膜癌发生及发展过程,CK7,Vim及P53可作为判断肿瘤的预后及选择治疗方案有用的参考指标.

北京1200例汉族人群中长链脂肪酸氧化酶G1528C基因突变筛查

目的: 研究北京地区1 200例汉族人群线粒体脂肪酸氧化代谢中的三功能蛋白酶(mitochondrial trifunctional protein,MTP)α亚单位的长链三羟基酰基辅酶A脱氢酶(long chain 3-hydroxyacyl-CoA dehydrogenase,LCHAD)G1528C基因的突变频率.方法: 应用聚合酶链反应-限制性片段长度多态性(polymerase chain reaction-restricted fragment length polymorphism, PCR-RFLP)技术分析1 200例汉族正常产妇脐血MTP的α亚单位G1528C基因突变携带情况.实验以西方人种的G1528C杂合子标本为阳性对照,同时设立阴性和空白对照作为实验技术质控标准.结果: 1 200例汉族产妇脐血标本G1528C 基因经PCR-RFLP突变筛查检测后,未见有与阳性对照标本相对分子质量相同的条带出现.结论: 中国人群与白种人之间可能存在着种族差异,西方人种中常见的MTPα亚单位的G1528C基因突变可能不是中国人种中常见的突变位点.

单细胞二重巢式PCR扩增影响因素初探

目的: 对影响单细胞二重巢式PCR扩增的因素进行初步探讨.方法:针对β-珠蛋白基因CD41-42、IVS-Ⅱ654突变位点区域采用二重巢式PCR,分别以不同的引物浓度组合、不同的Taq DNA聚合酶、不同的中和缓冲液、PCR反应前采用或不采用98 ℃预变性扩增单个淋巴细胞和/或单卵裂球,了解这些因素对PCR扩增效率的影响.结果: 不同的引物浓度组中,终浓度为0.25 μmol/L R1+F1引物对与 0.3 μmol/L R2+F2引物对配对扩增效率高;不同的Taq DNA聚合酶中TaKaRa EX Taq的扩增效率高;中和缓冲液-1(200 mmol/L Tricine)的扩增效率显著高于中和缓冲液-2(900 mmol/L Tris·HCl, pH 8.3/300 mmol/L KCl/200 mmol/L HCl)的扩增效率(P<0.05);单细胞PCR反应前采用98 ℃预变性与不采用98 ℃预变性的扩增效率间差异无统计学意义.结论:不同引物浓度组合、不同的Taq DNA聚合酶、不同的中和缓冲液对单细胞的二重巢式PCR的扩增效率存在明显差异,而PCR反应前采用98 ℃预变性不能提高PCR扩增效率.

儿童青少年双生子胰岛素敏感性的遗传度估计及影响因素分析

目的:分析影响儿童青少年的胰岛素敏感性的遗传和环境因素,并探讨其中体质指数(body mass index, BMI)、年龄和性别的作用.方法:选择5～18岁同性别双生子296对,平均年龄(12.4±3.5)岁,其中同卵双生子(MZ)223对,异卵双生子(DZ)73对.在DNA卵性鉴定基础上,应用Mx软件模型拟合分别计算BMI调整前后稳态模型胰岛素抵抗指数(homeostasis model assessment insulin resistance index, HOMA IR)和β细胞功能指数(HOMA β-cell function index,HBCI)的遗传度,并检验年龄和性别对于模型的作用.结果:HOMA IR与年龄、性别和BMI相关,HBCI与年龄相关,遗传分析HOMA IR、HBCI的模型为ACE,BMI调整前后HOMA IR男女生遗传度不同,HBCI无明显变化.调整后HOMA IR、HBCI遗传度分别为0.25、0.24.结论:儿童青少年人群中HOMA IR、HBCI受遗传和环境因素共同作用,环境因素的影响似乎更大;BMI是影响机体胰岛素敏感性的重要因素;年龄和性别对遗传度的影响可能不大.

中国汉族人群腓骨肌萎缩症Cx32基因突变分析

Objective: To investigate the Cx32 mutation features and the clinical manifestations of Chinese patients with Charcot-Marie-Tooth disease(CMT). Methods: Twenty-four of 65 unrelated CMT patients were selected for Cx32 mutation screening after the exclusion of the CMT1A 1.5 Mb duplication and male-to-male transmission. The motor and sensory nerve conduction studies were performed in all probands and most of their affected family members to establish the clinical CMT1 ,CMT2 or CMT intermediate diagnosis. The presence of mutations in the coding region of Cx32 was detected by single-strand conformation polymorphism analysis combined with direct sequencing. Results: We found 7 different point mutations in the coding region of Cx32 in a total of 7 families. All the patients were mildly to moderately affected with a clinical CMT1 or CMT intermediate diagnosis. The mutation Arg15Gln was inherited with X-linked recessive trait in family 1 involved in our study. The Arg75Trp mutation was detected in a family with X-linked dominant CMT and autosomal recessive nonsydromic hearing loss. The clinical phenotype of the Thr188Ala mutation was firstly reported. Conclusion: Seven different Cx32 point mutations were detected and the percentage of Chinese CMT families with Cx32 mutation is about 10% in our study. The inheritance model of CMT secondary to Cx32 mutation could be X-linked dominant, X-linked recessive or sporadic. Male patients are usually more severely affected than females with slower nerve conduction velocities. Cx32 mutation screening should be firstly performed in those CMT families without male-to-male transmission and CMT1A duplication.

体质性镶嵌型21三体与无精症一例报告

SUMMARY Constitutional full trisomy 21 is a common disorder in which abnormal spermatogenesis has been previously described. However, constitutional mosaic trisomy 21 in an otherwise normal but infertile male has not been explored. We report a case with low level mosaic trisomy 21 in a non-syndrome but azoospermic patient. We also propose that the patient's azoospermia may be related to the constitutional mosaic trisomy 21 and thus resulting in a late onset of testicular failure.

RNA干扰技术在医学遗传学中的应用

某些小的双链RNA可以高效特异地阻断体内特定基因表达,促使mRNA降解,诱使细胞表现出特定基因缺失的表型,称为RNA干扰(RNAi).RNAi同时也是体内抵御外在感染的一种重要保护机制.作为一种简单有效的代替基因敲除的遗传工具,RNAi将大大加速功能基因组学的研究进展,被Science评为2002年重要的科研成果之一.RNAi导致的基因沉默发生在转录后,所以被称为转录后基因沉默(PTGS).

腓骨肌萎缩症的分子遗传学研究

腓骨肌萎缩症也称为Charcot-Marie-Tooth病(CMT),是一类高发病率的周围神经系统单基因遗传病,可发生于世界范围的各个种族之中,发病率为1/2 500.遗传方式主要为常染色体显性遗传(AD),也可见常染色体隐性遗传(AR)及X连锁显性或隐性遗传(XD或XR).即使是同一家庭中的患者,其患病的严重程度也会不同.

核纤层蛋白病--一个基因,多种疾病

核纤层蛋白病(laminopathies)是指由LMNA基因及其编码蛋白lamin A/C异常引起的一组人类遗传病[1].根据临床特征不同,至今被认识的核纤层蛋白病已有10种,除一种由影响成熟lamin A形成的FACE-1基因突变引起外[2],其余9种均由LMNA基因突变引起,其中包括2种既可以常染色体显性又可以常染色体隐性遗传的遗传病:Emery-Dreifuss 肌营养不良(Emery-Dreifuss muscular dystrophy, EDMD,常显EDMD2,常隐EDMD3)[3,4] 和腓骨肌萎缩症2型(Charcot-Marie-Tooth2,常显AD-CMT2,常隐AR-CMT2)[5,6];6种常染色体显性遗传病:肢带型肌营养不良1B(limb girdle muscular dystrophy1B,LGMD1B)[7],扩张性心肌病伴心脏传导阻滞1A(dilated cardiomyopathy and cardiac conduction defects1A, CMD1A)[8],家族部分性脂肪营养不良(familial partial lipodystrophy, FPLD)[9],脂肪营养不良、胰岛素抵抗型糖尿病、弥漫性白黑皮病样丘疹、肝脂肪变性和心肌病综合征(lipoatrophy & insulin-resistant diabetes & disseminated leukomelanodermic papules & liver steatosis and cardiomyopathy,LDHPC)[10],Werner综合征(Werner syndrome, WRN)[11]和早老症(Hutchinson-Gilford progeria syndrome,HGPS)[12];1种常染色体隐性遗传病: Mandibuloacral dysplasia(MAD)[13].

医学遗传学在中国公共卫生事业中发挥重要作用--北京2004医学遗传学国际学术研讨会报告

The International Conference of Medical Genetics 2004 (ICMG2004) was held at Peking University Health Science Center on July 14-18, 2004. This conference is a part of the series that have been organized by the North American Association of Chinese Medical Geneticists (NAACMG) and the Chinese Medical Genetics Association (CMGA) and was initialized by the year of 2000 at Nanjing (ICMG2000, Nanjing). The mission of the series is to promote research, education, and clinical practice on medical genetics in China as well as in south Asian countries. This year, more than 200 participants from Mainland China, Taiwan, Hong Kong, England, and United States attended the ICMG2004. The conference opened with a remark addressed by Dr. Qi-de Han, the Vice Chairman of the Standing Committee of National Congress, who is the Director of Peking University Health Science Center and the Executive President of Peking University. Dr. Owen Rennet, Scientific Director of NICHD, NIH, gave a keynote speech at the opening session. Six sessions, chaired by Drs. Virginia Anderson, Wai-Yee Chan, Tian-jian Chen, Jiang Gu, Jian Han, Tao-Sheng Huang, Marilyn Li, Gary Lu, Ming Qi, Bai-Lin Wu, Nanbert Zhong, Chun-Yan Zhou, have covered various aspects of medical genetics with focus on birth defect, which is different from the main focus of neurogenetic disorders at ICMG2000. These aspects include inborn error of metabolism, intervention of birth defects, prenatal diagnosis and newborn screening, chromosome abnormalities, molecular basis of genetic disorders, environmental factors and birth defects, and genetic counseling and clinical management.

人DNA修复基因HR24L/HRAD17校正酵母细胞减数分裂缺陷表型

啤酒酵母(Saccharomyces cerevisiae)DNA修复基因RAD24在进化上具有高度保守性, 非洲粟酒酵母(Schizosaccaromyces pombe)的同源物则是RAD17.我们分离了啤酒酵母RAD24基因温度敏感突变株rad24L,进而用遗传互补法克隆出人类同源基因HR24L (北京医科大学学报,1999,31:269) .继我们报道之后,美国哈佛大学学者通过分析基因组信息,比较与非洲粟酒酵母RAD17同源片段,利用PCR方法扩增出人类RAD17同源cDNA,然后筛选文库获得人类RAD17(HRAD17)基因(Cancer Research, 1999,59:2023-2028),序列测定结果表明与我们克隆的HR24L是同一个基因.该基因编码的产物不仅参与DNA损伤切除修复和重组修复,而且还参与细胞周期检定点调控.鉴于细胞周期检定点调控是体细胞进行有丝分裂(mitosis)和生殖细胞进行减数分裂(meiosis)共有的周期性事件,因此,我们用遗传学方法分离酵母细胞减数分裂突变株,用功能互补法研究人HR24L基因的互补作用.

分子和细胞遗传学新技术在出生缺陷诊断及防治中的应用

SUMMARY Fluorescence in situ hybridization (FISH) has become an important diagnostic tool as an adjunct to classical cytogenetics. FISH utilizes DNA probes comprised of specific nucleic acid sequences tagged with fluorescent molecules to identify the number and location of specific DNA sequences in human cells. These probes can be used to determine various numerical and structural chromosomal aberrations, in many cases, gene dosage and/or structure alterations. Chromosomal abnormalities are responsible for a considerable number of birth defects, and more than 50% of spontaneous abortions. These numbers have been significantly higher since the advent of FISH technology that allows the detection of submicroscopic chromosome alterations. The clinic application of FISH technology in postnatal, prenatal, and preimplantation diagnoses has been playing an important role in the diagnosis and prevention of birth defects. As new technologies evolve, more and more new FISH techniques - such as subtelomeric FISH, multicolor FISH (M-FISH), comparative genomic hybridization (CGH), and microarray - are used in clinical diagnoses, the role of FISH technology in both research and clinical aspects of birth defects will surely continue to expand.

溶酶体内胱氨酸可促进细胞凋亡并导致胱氨酸贮积症的表型发生

SUMMARY　Nephropathic cystinosis is a lethal inborn error of metabolism that destroys kidney function by age 10 years. It is characterized by lysosomal cystine accumulation. How the cystine causes the phenotype is an open question. We propose that during apoptosis, permeablized lysosomes permit cystine to reach the cytosol where mixed disulfide formation occurs, augmenting apoptosis by interaction with a variety of pro-apoptotic proteins.

等位基因特异性引物延伸法在婴儿型和幼儿型神经元蜡样质脂褐质沉积病产前诊断中的应用

SUMMARY Infantile (INCL, NCL1) and late-infantile (LINCL, NCL2) neuronal ceroid lipofuscinoses have been found to result from genetic deficiency of genes CLN1 and CLN2, respectively. The application of molecular analyses can facilitate prenatal diagnosis for families affected by NCL1 or NCL2, in which the familial mutation(s) have been identified. Molecular testing with allele-specific primer extension and DNA sequencing was performed in nine pregnancies, four from two NCL1 families and five from five NCL2 families. Lysosomal enzyme activity assays were carried out as well.Four fetuses from three pregnancies in NCL1 families were found to be carriers for a mutation 451C-T in the CLN1 gene and one was normal. Prenatal testing of three NCL2 families who carried mutation R208X in the CLN2 gene showed that all fetuses were carriers. In NCL2 families who carried either mutation IVS5-1C or/and IVS5-1A two normal pregnancies were detected. Our studies indicate that DNA testing, which may provide definitive prenatal diagnosis for NCL, may be used in combination with lysosomal enzyme activity analyses.

常见线粒体DNA病的分子遗传学研究进展

SUMMARY Diagnosis of mitochondrial disorders has been difficult due to the clinical and genetic heterogeneity, as well as unique features of mitochondrial genetics. Definitive diagnosis requires the identification of molecular defects in either the mitochondrial or the nuclear genome. We describe the clinical and molecular characteristic of some common mitochondrial syndromes and molecular methodologies available for the detection of mitochondrial DNA mutations. This review provides overview of current molecular diagnosis of mitochondrial DNA disorders that is useful in patient care and genetic counseling.

促黄体激素受体突变导致的性器官发育异常

SUMMARY The Luteinizing hormone/chorionic gonadotropin receptor (LHR) plays a critical role in human male sexual development. Both gain-of-function and loss-of-function mutations of the LHR have been described. Gain-of-function mutations are dominant and cause constitutive activation of the receptor resulting in familial male-limited precocious puberty (FMPP). All activating mutations are single point mutations and are located in the transmembrane domain (TM). TM helix Ⅵ harbors the largest number of activating mutations with the codon of Asp-578 being the hot-spot of mutation. Besides causing abnormal sexual development, constitutively activated LHR may predispose an individual to the development of testicular neoplasia. The anti-thesis of FMPP is Leydig cell hypoplasia (LCH). This is caused by mutations that inactivate the LHR resulting in subnormal male sexual development or male pseudohermaphroditism. Inactivating mutations are recessive. The genetic cause of LCH is variable and there is no mutation hot-spot. Genotype-phenotype correlation can be identified in LCH with the milder form caused by mutated LHR with residual activity and the severe form caused by absence of signal transduction activity of the mutated receptor. Molecular diagnosis of the disorders caused by mutation of the LHR can be achieved by direct sequencing of the LHR gene.

治疗相关的急性髓系白血病的临床细胞遗传学诊断

SUMMARY Therapy-related acute myeloid leukemia (tAML) is one of the two forms of secondary acute myeloid leukemia, with one derived from de novo myelodysplastic syndrome (MDS) and the other from exposure to environmental or therapeutic agents such as radiation and toxins. There has been a marked increase in the number of incidences of therapy-related acute myeloid leukemia. It has become a distinctive disease because of its etiology and genetic tumorigenesis. The majority of tAML resulting from the use of cytotoxic agents can be divided into two groups based on the drugs administered to the patient. The first group includes the use of alkylating agents, and the second group includes agents that bind to the enzyme DNA-topoisomerase Ⅱ. Due to the unfavorable outcome of the disease and the need for prompt intensive treatment, a timely accurate diagnosis of tAML is critical to patient care. Cytogenetic study can detect abnormalities most commonly associated with tAML and thus providing important diagnostic information. However, utilizing cytogenetic analysis alone cannot guarantee prompt and accurate results. In this study, an interesting case with therapy-related myelodysplastic syndrome and acute myeloid leukemia (tMDS/tAML) will be presented. A laboratory diagnostic strategy for tAML laboratory diagnosis will also be proposed.

艾滋病治疗的新希望

21三体与母亲年龄关系的新发现

增加的淀粉样β蛋白(Ab42)和晚发型阿尔茨海默病与尿激酶型血纤维蛋白溶酶原激活因子基因中的单个核苷酸多态性相关

长期紧张对染色体端粒的影响

基因表达与哺乳动物DNA碱基GC含量的关系:统计学意义和生物相关性

微卫星(microsatellite,MS)

DNA错配修复(DNA mismatch repair,MMR)