染色体核型及血清碱性磷酸酶水平在慢性粒细胞白血病病情预测中作用

目的 研究慢性粒细胞白血病(CML)患者骨髓单个核细胞染色体核型与血清碱性磷酸酶(ALP)水平间变化关系,探讨细胞遗传学变化及ALP水平在患者病情及预后判断中的价值.方法 选择不同时期CML患者,检测其血清ALP,并取骨髓有核细胞采用直接法或24小时培养法、R带显色技术作染色体分析.结果 CML患者ALP水平高于正常对照组,加速期急变期患者复杂核型出现率及血清ALP水平显著高于慢性期患者,且ALP水平与髓内幼稚细胞数水平呈正相关,PH1阳性核型CML患者与复杂核型CML患者血清ALP水平差别不明显.结论 CML患者血清ALP水平及染色体复杂核型反应该期患者疾病特征,对CML疾病分期、预后判断有价值,两者间的一致性有待进一步研究.     

RecQ helicase acts before RuvABC,RecG and XerC proteins during recombination in recBCD sbcBC mutants of Escherichia coli

The RecQ helicase is required by the RecF recombination pathway that is operative in recBC(D) sbcB sbcC(D) mutants of Escherichia coli. Genetic data suggest that RecQ participates in resection of DNA ends during initiation of recombination. In vitro, RecQ can unwind a variety of DNA substrates, including recombination intermediates such as D-loops and Holliday junctions. However, its potential role in processing of recombination intermediates during the late stage of the RecF pathway has not been genetically tested. Here we studied the effect of a recQ mutation on transductional recombination and DNA repair after γ-irradiation in ΔrecBCD ΔsbcB sbcC strains deficient for RuvABC, RecG and XerC proteins. RuvABC and RecG proteins process recombination intermediates in the late stage of recombination, whereas XerC is required to resolve chromosome dimers formed upon recombination. Our results do not reveal any substantial synergistic effect between the recQ mutation, on one hand, and ruvABC, recG and xerC mutations on the other. In addition, the recQ mutation suppresses chromosome segregation defects in γ-irradiated ruvABC recG and xerC mutants. These results suggest that RecQ acts upstream of RuvABC, RecG and XerC proteins, a finding that is compatible with its primary role in initiation of the RecF recombination pathway.     

Turner综合征自发性青春发育分析

目的探讨先天性卵巢发育不全综合征（Turnersyndrome,TS）患儿自发的青春发育与染色体核型及性激素水平之间的关系。方法30例Turner综合征患儿进行染色体检查,评估第二性征及性腺发育情况,检测性激素水平。结果染色体核型分4组,第1组45,XO,10例;第2组嵌合型,9例;第3组x染色体结构畸变,10例;第4组伴有Y染色体,1例。30例患儿随访至15周岁,其中10例出现不同程度的自发性青春发育,20例呈无性发育,4组患儿中以嵌合型TS出现自发青春发育几率最大。有青春发育患儿的性激素水平与无性发育患儿的性激素水平有显著差异。结论Turner综合征患儿自发性青春发育与染色体核型及性激素水平有密切相关性。     

MLPA技术在检测胎儿非整倍体异常中的应用

目的探讨多重探针连接依赖式扩增（multiplex ligation—dependent probe amplification,MLPA）在快速检测胎儿染色体非整倍体异常中的应用价值。方法344例产前诊断标本同时进行MLPA检测及核型分析,所有样本进行MLPA获得的扩增产物信息经Coffalyserv9．4软件（Holland—MRC公司）进行定量分析,观察样本DNA拷贝数的变化,并将所得结果与染色体核型分析结果进行比较,计算其检测的敏感度、特异度及阳性预测值。结果MLPA分析在标本接收后24h内即可得出结果,共检出染色体倍体异常产前诊断标本5例,包括唐氏综合征（Downsyndrome,47,＋21）6例、爱德华氏综合征（Edwardssyndrome,47,＋18）l例。MLPA检测24h报告结果临床符合率为97．7％。结论MLPA检测21、18、13、X、Y等染色体非整倍体疾病时,与核型分析相比较,MLPA是一种快速、高效的分析非整倍体的产前诊断的方法,具有临床应用价值。     

邯郸地区1024例复发性流产患者的染色体核型分析

目的分析比较染色体异常与复发性流产的关系。方法对复发性流产夫妇进行外周血染色体核型分析。结果本文对1024例复发性流产的夫妇染色体检查中发现48例染色体异常核型,检出率为4．69％。结论染色体核型异常与复发性流产存在着一定的关系。     

柳州地区6876例产前诊断羊水细胞染色体核型分析

目的分析妊娠中期进行产前诊断的高危孕妇羊水细胞染色体核型,了解此期异常核型出现的频率及类型。方法6887例具备产前诊断指征的妊娠妇女,在知情选择的情况下行羊膜腔穿刺术及染色体核型检测。结果6876例羊水细胞培养成功,成功率为99．84％（6876／6887）。在6876例羊水细胞培养成功的染色体核型中,检出异常核型107例,异常率为1．56％,常见核型为三体型,占异常核型47．66％。结论羊水细胞学检查作为一项产前诊断技术对于指导优生优育,降低缺陷儿的出生具有重要意义。     

应用MLPA技术进行3例猫叫综合征的分子遗传学分析

目的通过应用多重连接依赖式探针扩增（MLPA）技术对3例猫叫综合征（CDCS,5p缺失综合征）进行分析,旨在探索可快速诊断CDCS的分子遗传学方法。方法对3个CDCS患者及其父母、患者1的异卵双生之姐姐,进行MLPA分析,检测CDCS关键区域5p15．33：包括hTERT基因在内的9个位点的基因拷贝数的变化;同时,对相应标本进行染色体G-显带核型分析。结果在接到标本24—48h,MLPA示：3例患儿均存在CDCS关键区域5p15．33包含hTERT在内的基因缺失,其父母及患者1异卵双生之姐姐未见缺失。7—10天后G显带染色体核型分析示：患儿2、3为单纯5号短臂（5p）末端缺失,其父母正常;患儿1病例在国内尚属少见,核型为：45,XY,-22,-5p,4-der（5）t（5;22）,携带了一条源于5p和22p易位而来衍生的5号染色体,其父母及异卵双生之姐姐均正常。MLPA与核型分析结果-致：3例患儿均为CDCS患者。结论MLPA是-种可快速诊断CDCS的分子遗传学方法,具有临床应用价值。     

Low oxygen delays fibroblast senescence despite shorter telomeres

It has been widely accepted that telomere shortening acts as a cell division counting mechanism that beyond a set critical length signals cells to enter replicative senescence. In this study, we demonstrate that by simply lowering the oxygen content of the cell culture environment 10-fold (20–2%) extends the replicative lifespan of fetal bovine fibroblasts at least five-times (30–150 days). Although, low oxygen fibroblasts display a slightly slower rate (P > 0.05) of telomere attrition than their high oxygen counterparts (171 bp versus 182 bp/PD), late passage fibroblasts (>50 PD) that have extended their replicative capacity under low oxygen conditions exhibited significantly (P < 0.05) shorter telomere lengths (11,135 ± 467 bp) compared to senescent cells (25–34 PD) cultured under high oxygen conditions (14,827 ± 1173 bp). There was a significant increase (P < 0.05) in chromosomal abnormalities with continual cell division under both high and low oxygen environments, however, fibroblasts displayed a significant reduction (P < 0.001) in chromosomal abnormalities at low oxygen tensions compared to those under 20% oxygen. These apparent protective effects on telomere shortening, delayed senescence and reduced chromosomal aberrations may be attributed to the up-regulation of telomerase activity observed for fibroblasts cultured under low oxygen. These results are consistent with the idea that a critically short telomere length may not be the sole trigger of replicative senescence, but may be regulated by the integrity of telomere structure itself and/or the amount of oxidative DNA damage in the cell.     

Could a patient with SMC1A duplication be classified as a human cohesinopathy?

The disorders caused by mutations in genes encoding subunits and accessory proteins of cohesin complex are collectively termed as cohesinopathies. The best known cohesinopathy is Cornelia de Lange Syndrome (CdLS), which is a multisystem developmental disorder characterized by facial dysmorphism, limb malformations, growth and cognitive impairment. Mutations in five genes, encoding subunits of the cohesin complex (SMC1A, SMC3, RAD21) and its regulators (NIPBL, HDAC8), are responsible for ～70% of CdLS cases. We describe a 16‐year‐old boy with facial dysmorphism, growth retardation, intellectual disability, hirsutism and small hands, who has a small Supernumerary Marker Chromosome (sSMC) present in mosaic form. sSMC is composed of two duplicated segments encompassing 17 genes including SMC1A gene, at the regions Xp11.22 and Xp11.21q11.1. Clinical comparison between our patient with a previously reported individual with a SMC1A duplication and four male carriers of similar sSMC reported in databases, suggest that they all share clinical features related to cohesinopathies. Although our patient does not have the classical CdLS craniofacial phenotype, he has pre and postnatal growth retardation, intellectual disability and mild musculoskeletal anomalies, features commonly seen in patients with cohesinopathies.     

广州地区370例孕早期绒毛染色体核型分析

目的探讨孕早期绒毛染色体异常核型与产前诊断各指征之间的联系。方法对370例高危孕妇行羊膜腔穿刺术抽取绒毛进行绒毛染色体核型分析。结果370例孕妇羊水培养成功357例,成功率96．49％。发现异常核型86例,异常核型检出率为213．24％。结论绒毛染色体检查是常用的孕早期产前诊断检查技术,能够有效的对异常胎儿进行确诊。