利用PCR技术检测537份新疆结核病人痰标本中的结核分枝杆菌

目的 提高聚合酶链反应在检测人结核分枝杆菌中的特异性和敏感性。方法 在聚合酶链反应中对4种DNA片段即结核杆菌特异插入列IS6110,IS1081,和16SrRNA,65kDa摸板进行了比较;为获取较多的细菌DNA,临床痰标本处理采用了国际标准化方法主要包括用一定量的N－乙酰－L半胱胺酸和氢氧化钠处理痰标本;改进了RCR混和液的成份即添加了甘油,dUTP－尿嘧啶糖基化酶。结果 选择IS6110作为结核杆菌特异性摸板用于检测细菌DNA,制备出了6批人结核杆菌PCR检测试剂盒,在对来自新疆结核病研究所的537份痰标本的检测中发现,谝试剂盒检测的特异性为65.97%,敏感性为93.53%。结论 改良TB－PCR试剂盒显示有较高的敏感性,特异性还有待于进一步完善,该试剂盒在临床诊断中有一定的价值。     

结核分枝杆菌双靶标环介导恒温扩增检测方法的建立与应用

目的建立基于双靶标环介导恒温扩增(LAMP)的结核分枝杆菌(MTB)检测技术并应用于临床。方法以结核分枝杆菌复合群(MTBC)插入序列IS6110和MTB mtp40基因为检测靶标,分别设计1套LAMP引物。通过引物浓度和反应条件优化,建立基于双靶标的检测方法(mtp40-LAMP和IS6110-LAMP),比较2种方法的灵敏度和特异性。应用建立的mtp40-LAMP和IS6110-LAMP方法与PCR、萋-尼氏抗酸染色法和分枝杆菌分离培养法,分别对55例患者的痰标本进行检测与鉴定,通过对其结果的比较分析评价mtp40-LAMP和IS6110-LAMP方法的实用性。结果灵敏度试验显示,mtp40-LAMP和IS6110-LAMP方法可检出MTB基因组DNA最低浓度为125 fg/μl,比常规的PCR方法高10～100倍。mtp40-LAMP和IS6110-LAMP方法的特异性为100%,能检测MTB菌株并能从MTBC中鉴别MTB。痰标本检测显示,IS6110-LAMP与PNB鉴定结果一致性检验的Kappa值为0.881(P0.01),mtp40-LAMP与TCH鉴定结果的Kappa值为0.887(P0.01)。与PCR方法和萋-尼氏抗酸染色法检测结果比较,mtp40-LAMP和IS6110-LAMP方法敏感性更高。反应体系中加入MG指示剂可直接通过肉眼观察颜色变化进行结果判定,实现了快速闭管检测。从样本处理(35 min)、扩增反应(40 min)到结果验证(1～2 min),整个检测过程80 min内即可完成。结论基于LAMP技术建立的mtp40-LAMP和IS6110-LAMP双靶标检测方法敏感性高、特异性强,能够快速、准确地检测和鉴别MTB,可作为潜在的MTB快速筛查或诊断工具。     

套式PCR及测序方法用于痰标本中结核分枝杆菌rpoB耐药基因突变检测

目的应用套式PCR—DNA测序方法直接检测痰标本中结核分枝杆菌相关的rpoB基因突变，以期建立一种直接检测分枝杆菌耐利福平的快速方法，并评价其临床应用价值。方法采用套武PCR—DNA测序方法直接检测112例活动性肺结核患者和20例非结核性肺部疾病患者痰、标本中结核分枝杆菌rpoB基因突变情况。同份痰标本同时做涂片抗酸染色，罗氏培养及菌型鉴定。结果112例活动性肺结核患者痰标本套式PCR扩增87例呈阳性，产物DNA测序31例有rpoB基因突变。其中分离出耐利福平株的32例痰中29例发生了基因突变，耐药突变率90．6％（29／32），39例菌阴（涂阴培阴）痰中有2例发生突变。分离出对利福平敏感株的37例痰中未发生突变，20例非结核性肺部疾病患者痰标本套式PCR扩增均为阴性，特异性100％。结论套式PCR—DNA测序可望为直接检测临床痰标本中结核分枝杆菌耐利福平的准确、特异、快速的方法。     

rDNA探针杂交检测病人痰标本中结核杆菌的研究

目的 应用结核分枝杆菌特异的rDNA探针杂交检测痰标本中的结核杆菌rDNA,评价其在临床标本检测中的应用价值。方法 用引物b对结核分枝杆菌16S-23SrDNA间隔区序列进行扩增,同时加入生物素标记,制成250bp的rDNA探针。对该探针的敏感性、特异性进行了研究,并对90份结核病人,30份非结核病人痰标本的PCR产物进行了斑点杂交检测。结果 rDNA探针检测引物bPCR扩增产物的敏感性为100pg。rDNA探针与受试24种分枝杆菌和11种非分枝杆菌引物bPCR扩增产物杂交只有结核分枝杆菌、胃分枝杆菌为阳性杂交,特异性较高。而rDNA探针对90份结核病人痰标本引物b扩增产物检测的阳性率为80.2%,高于PCR扩增产物电泳检测结果 (64%)。rDNA探针与30份非结核病人痰标本杂交结果均为阴性杂交。结论 rDNA探针与引物bPCR扩增相结合能提高结核病人痰标本检测的敏感性与特异性。     

石蜡包埋组织实时荧光定量聚合酶链反应检测在结核病诊断中的价值

目的探讨石蜡包埋组织实时荧光定量聚合酶链反应(FQ-PCR)检测结核分枝杆菌DNA在结核病诊断中的价值。方法275例组织标本行常规组织病理学检查、抗酸染色,并对石蜡包埋组织应用实时荧光定量聚合酶链反应检测结核分枝杆菌DNA。结果275例FQ-PCR检测结核分枝杆菌DNA阳性211例(76.7%),病理诊断为结核183例(66.5%),抗酸染色阳性23例(8.4%)。病理诊断为结核者FQ-PCR阳性率为93.4%,抗酸染色阳性者FQ-PCR阳性率95.7%。结论实时荧光聚合酶链反应技术敏感性高、其与组织病理学相结合可以提高诊断率。     

结核分支杆菌DNA的单管巢式聚合酶链反应检测

目的探讨单管巢式聚合酶链反应（ＳＮＰＣＲ）检测石蜡包埋组织结核分支杆菌ＤＮＡ的特异性和敏感性。方法应用普通ＰＣＲ（ＧＰＣＲ）、双管巢式ＰＣＲ（ＤＮＰＣＲ）和ＳＮＰＣＲ对结核分支杆菌ＢＣＧ和３０例结核性淋巴结炎石蜡包埋组织进行结核分支杆菌复合群ＩＳ６１１０特异插入序列片段ＤＮＡ检测。结果ＤＮＰＣＲ和ＳＮＰＣＲ检测ＢＣＧＤＮＡ均于１５ｆｇ以上呈现阳性结果，其敏感性明显优于ＧＰＣＲ（４８０ｆｇ）。ＧＰＣＲ、ＤＮＰＣＲ和ＳＮＰＣＲ检测３０例结核性淋巴结炎阳性率分别为４３％、１００％和１００％，抗酸染色阳性率（１０％）与３种ＰＣＲ法相比差异有非常显著意义（均Ｐ＜０．０１）。ＧＰＣＲ阳性率与ＤＮＰＣＲ和ＳＮＰＣＲ相比差异亦具非常显著意义（均Ｐ＜０．０１）。ＳＮＰＣＲ阳性率与ＤＮＰＣＲ相同。结论巢式ＰＣＲ检测淋巴结石蜡包埋组织结核分支杆菌的敏感性显著高于ＧＰＣＲ，其中ＳＮＰＣＲ具有与ＤＮＰＣＲ相同的特异性和敏感性，并具有更大的实用价值。     

套式PCR及测序方法用于痰标本中结核分枝杆菌rpoB耐药基因突变检测

目的应用套式PCR-DNA测序方法直接检测痰标本中结核分枝杆菌相关的rpoB基因突变,以期建立一种直接检测分枝杆菌耐利福平的快速方法,并评价其临床应用价值。方法采用套式PCR-DNA测序方法直接检测112例活动性肺结核患者和20例非结核性肺部疾病患者痰标本中结核分枝杆菌rpoB基因突变情况。同份痰标本同时做涂片抗酸染色,罗氏培养及菌型鉴定。结果112例活动性肺结核患者痰标本套式PCR扩增87例呈阳性,产物DNA测序31例有rpoB基因突变,其中分离出耐利福平株的32例痰中29例发生了基因突变,耐药突变率90.6%(29/32),39例菌阴(涂阴培阴)痰中有2例发生突变。分离出对利福平敏感株的37例痰中未发生突变,20例非结核性肺部疾病患者痰标本套式PCR扩增均为阴性,特异性100%。结论套式PCR-DNA测序可望为直接检测临床痰标本中结核分枝杆菌耐利福平的准确、特异、快速的方法。     

分子病理学诊断颈部淋巴结结核及其耐药性的应用价值

目的 评价分子病理学方法诊断颈部淋巴结结核及其耐药性的临床应用价值。方法 搜集2010年3月至2013年10月首都医科大学附属北京胸科医院病理科收治的符合纳入标准(临床症状和体征均符合颈部淋巴结结核、抗结核药物治疗均有效)的全部97例颈部淋巴结结核患者(结核组);以及符合纳入标准(通过病理学或临床检测结果明确诊断为其他淋巴结疾病)的全部20例其他淋巴结病变患者(非结核组)的石蜡包埋标本。所有标本以萋-尼(Z-N)抗酸染色法查找抗酸杆菌,荧光定量聚合酶链式反应(FQ-PCR)检测结核分枝杆菌特异基因序列IS6110;以临床最后诊断为标准,比较两种方法的检测效能;并对FQ-PCR检查结果为阳性且结核分枝杆菌DNA含量满足耐药突变检测下限的标本,以探针熔解曲线法检测利福平、异烟肼耐药相关基因突变情况。结果 以临床最后诊断为标准,抗酸染色和FQ-PCR检测结核组的敏感度分别为22.7%(22/97)和67.0%(65/97);FQ-PCR技术检测敏感度明显高于抗酸染色法,差异有统计学意义(χ²=38.53,P<0.001)。抗酸染色和FQ-PCR检测非结核组标本均为阴性,特异度均为100.0%(20/20)。抗酸染色和FQ-PCR的阳性预测值分别为100.0%(22/22)和100.0%(65/65),阴性预测值分别为21.1%(20/95)和38.5%(20/52),符合率分别为35.9%(42/117)和72.6%(85/117)。对41例FQ-PCR检查结果为阳性且结核分枝杆菌DNA含量满足耐药突变检测下限的患者标本进行结核分枝杆菌耐药基因突变检测,利福平和异烟肼可评估标本分别为10份(例)和27份(例),其中利福平耐药1份(例),异烟肼耐药13份(例)。 结论 分子病理学诊断技术在颈部淋巴结结核石蜡包埋标本中检测结核分枝杆菌DNA的敏感度和特异度较高,并且能筛查可能的耐药患者,可为颈部淋巴结结核的正确诊断与合理化治疗提供依据。     

应用磁纳米捕获-PCR技术检测痰液结核分枝杆菌的研究

目的采用磁纳米捕获技术富集痰液中的结核分枝杆菌,以提高PCR检测的灵敏度,快速诊断结核病。方法以普通PCR为对照,采用磁纳米捕获技术富集187份结核和非结核呼吸系统疾病患者痰标本中的结核分枝杆菌,进行PCR检测。结果 152份肺结核患者痰标本41份(27.0%)涂片抗酸染色阳性,72份(47.4%)普通PCR检测阳性,126份(82.9%)磁纳米捕获-PCR检测阳性。35份非结核呼吸系统疾病患者,痰标本中抗酸染色均为阴性,1份普通PCR和磁纳米捕获-PCR检测均阳性,该患者临床诊断肺部感染合并陈旧性肺结核。结论采用磁纳米捕获技术富集痰液中的结核分枝杆菌,可显著提高PCR检测的灵敏度。     

应用扩增直接重复序列DNA片段对泰国结核分支杆菌菌株基因差异的研究

背景:发展并使用一种用于研究结核分支杆菌基因差异的聚合酶链反应(PCR)设计:结核分支杆菌H_(37)Rv的两个多态性DNA片段被鉴定和测序。然后引物被设计以用于对两个多态性片段同时进行扩增。该方法被用于研究179例临床结核菌分离株,这些菌株以前曾用IS6110的Southern杂交鉴定。结果:两个多态性片段均含有直接重复序列。其中一个片段的直接重复序列位于α-异丙基苹果酸酯合成酶基因的编码序列之间。179个菌株的两个片段经过扩增后,PCR产物的40个型能够被鉴定。该方法能够将38个IS6110单带菌株区分为23个型。属于北京家族的菌株中的大多数具有与H_(37)Rv相同的PCR产物。Nonthaburi组成员的PCR产物彼此间是相似的。结论:这些结果符合北京家族和Nonthaburi组成员起源于两个共同祖先的假说。该PCR方法可能有助于对含IS6110单拷贝的结核菌菌株进行区分。     

AmpliSensor—聚合酶链反应定量检测肺结核患者外周血结 …

目的 探讨ＡｍｐｌｉＳｅｎｓｏｒ－聚合酶链反应定量检测外周血中结核分支杆菌ＤＮＡ在肺结核的应用价值。方法 采用ＱｌＡａｍｐ和ＡｃｕＰｕｒｅ法提取，制备全血中模板ＴＢ－ＤＮＡ，应用ＡｍｐｌｉＳｅｎｓｏｒ－ＰＣＲ定量检测，并与ＩＳ６１１０－单管巢式聚合酶链反应（ＳＮ－ＰＣＲ）作比较。结果２００例肺结核患者的血液标本中，两种方法测得结核分支杆菌ＤＮＡ的阳性率分别为６０．５％、６３．５％。８５例非结核肺病     

Detection of Mycobacterium tuberculosis in clinical samples using insertion sequences IS6110 and IS990

To detect Mycobacterium tuberculosis in clinical samples, we used the M. tuberculosis-complex specific insertion sequence IS990 as the target in a simple DIG-PCR ELISA assay, as this element is present as a single copy in all strains of M. tuberculosis we have examined to date. The IS990 test was compared with a similar PCR that utilizes IS6110 as target. For detection of PCR product, digoxigenin-11-dUTP (DIG-dUTP) was incorporated into the product. After amplification, the PCR product was hybridized with biotinylated capture probe, which was complementary to the inner part of the amplicon. The hybrid was captured onto streptavidin-coated microtiter plate and DIG-labeled PCR product was detected using a peroxidase-conjugated antibody to DIG. We evaluated DIG-PCR ELISA for the detection of M. tuberculosis DNA in 265 respiratory and non-respiratory specimens taken from patients with known and suspected tuberculosis disease or from controls. The sensitivity and specificity of both IS990-based test and IS6110-based test was 96.5% and 95.3% respectively, comparable to the sensitivity and specificity of the IS6110-based test. The results demonstrate that the IS990 PCR ELISA test is a rapid and sensitive tool for the detection and identification of M. tuberculosis in clinical samples, and may have advantages to the more widely used IS6110-based tests, particularly in areas where IS6110-negative strains are found.     

Evaluation of Amplicor- and IS6110-PCR for direct detection of Mycobacterium tuberculosis complex in Singapore

One hundred and seventy-eight samples from 168 individuals were tested for Mycobacterium tuberculosis complex ( Mtc ) using Amplicor PCR, IS6110 -PCR (in-house), acid fast (AF)-staining and culture. Thirty-one samples were positive by culture, but 37 samples were later resolved to be truly positive for Mtc . Of these, Amplicor detected 32 (86.5%), IS6110 -PCR detected 31 (83.6%), and AF-staining 21 (56.8%). None of the 141 Mtc -negative samples was positive by these tests, thus giving 100% specificity. Although the IS6110 -PCR was more sensitive than Amplicor in detecting spiked Mtc DNA, it was not more sensitive than the latter in detecting Mtc in clinical samples. Reasons likely to account for the PCR false negativity were (i) sample inoculum size, (ii) nonuniform samples due to clumping effect of Mtc and (iii) the absence of target gene sequences for IS6110 -PCR. Culture negativity, on the other hand, was likely to be associated with nonviable Mtc . Amplicor PCR is promising for direct detection of Mtc . The IS6110 -PCR, however, may not be as suitable because of possible existence of IS6110- deleted Mtc strain in Singapore.     

Detection of Mycobacterium tuberculosis by a polymerase chain reaction colorimetric dot-blot assay.

SETTING: A public health laboratory in a tuberculosis-endemic region in Brazil. OBJECTIVE: To evaluate the accuracy of a combined polymerase chain reaction (PCR) colorimetric dot-blot protocol for Mycobacterium tuberculosis detection in clinical samples in a public health laboratory. DESIGN: Eighty clinical samples (13 cerebrospinal fluid, 31 induced sputum, 17 expectorated sputum, eight bronchoalveolar lavage and 11 pleural fluid) were assayed with the developed protocol. The accuracy of polymerase chain reaction (PCR) dot-blot methodology was compared to PCR agarose gel electrophoresis (PCR-AG) using as a gold standard the bacteriological result (culture and biochemical identification) combined with clinical follow-up. One internal region of the IS6110 repetitive element of the M. tuberculosis complex was selected for amplification and the amplified product transferred to nylon membranes to be detected by biotinylated DNA probe. RESULTS: Overall sensitivity and specificity obtained were respectively 90% and 97% for PCR-AG and 95% and 97% for the PCR dot-blot. Among the 56 respiratory specimens, the sensitivity and specificity results for PCR-AG were respectively 88% and 95%, and for PCR dot-blot they were 94% and 95%. Among the 24 non-respiratory specimens the sensitivity and specificity results were respectively 83% and 100% for PCR-AG, and 100% and 100% for the PCR dot-blot protocol. CONCLUSION: The results demonstrated that the PCR dot-blot assay may be helpful in the diagnosis of tuberculosis, and feasible even in resource-poor countries.     

Development and evaluation of a multiplex polymerase chain reaction for the detection of Mycobacterium tuberculosis from pulmonary specimens

Abstract Background: The diagnosis of pulmonary tuberculosis is still a major challenge. Using a polymerase chain reaction (PCR), one can detect Mycobacterium tuberculosis in clinical samples within a few hours. However, single gene targets may result in false negativity due to the absence of target DNA in some M. tuberculosis isolates. The objective of this study was to develop and evaluate a multiplex PCR (M-PCR) using IS6110 and devR primers for the detection of M. tuberculosis in sputum samples. Methods: Sputum samples were collected from: (1) 200 confirmed cases of tuberculosis; (2) 100 suspected cases of tuberculosis diagnosed on the basis of clinical and radiological findings; (3) 200 non-tubercular patients suffering from respiratory diseases other than tuberculosis, in whom tuberculosis had been excluded. All 500 sputum samples were subjected to PCR using IS6110 primers, and M-PCR using IS6110 and devR primers; results were compared with conventional techniques. Results: It was found that M-PCR was 97.5% successful in detecting the presence of tuberculosis in the confirmed tuberculosis group as compared to 84.5% by IS6110-based PCR. In the suspected tuberculosis group, M-PCR could detect 45% of cases as compared to 40% by IS6110-based PCR. Overall, the specificities of both the PCR and M-PCR were found to be 96.5%. Conclusions: This study demonstrated that the M-PCR assay is more sensitive than the IS6110-based PCR for the detection of M. tuberculosis in sputum specimens and could be applied in situations of highly suspected tuberculosis when all others tests including IS6110 PCR are negative.     

Evaluation of polymerase chain reaction, tuberculostearic acid analysis, and direct microscopy for the detection of Mycobacterium tuberculosis in sputum.

Tuberculosis remains a major global cause of morbidity and mortality. There is an urgent need for improved bacteriologic diagnosis of Mycobacterium tuberculosis infection. Three methods for rapid identification of M. tuberculosis in sputum samples (direct microscopy, gas chromatography-mass spectrometry [GC-MS], and polymerase chain reaction [PCR]), were compared with culture on Lowenstein-Jensen medium. Growth of M. tuberculosis was observed in 38 of 145 sputum samples. Detection of acid-fast bacilli by direct microscopy gave a sensitivity of 66% and a specificity of 100%. Detection of tuberculostearic acid by GC-MS gave a sensitivity of 55% and a specificity of 87%. Amplification by PCR of a fragment of the insertion sequence IS6110 gave a sensitivity of 95% and a specificity of 93% compared with culture and a corrected specificity of 99% compared with both culture and clinical data. This study indicates that PCR can be adapted for clinical use and is the method of choice for rapid diagnosis of pulmonary tuberculosis.     

Evaluation of culture and PCR-based assay for detection of Mycobacterium tuberculosis from sputum collected and stored on filter paper

We evaluated the use of culture and PCR-based assay for the direct detection of Mycobacterium tuberculosis (MTB) from sputum collected and stored on filter paper at room temperature for 5 days; the results were compared with those of staining and conventional culture of fresh sputum before storage (the 'gold standard'). Out of 231 sputum specimens examined, MTB was recovered from 124 samples by culture before storage. The culture positivity rate was significantly decreased to 70% after 5 days storage. For PCR assay, a fragment of 377 bp of the IS6110 sequence was amplified and detected using three methods: first PCR product combined with agarose gel electrophoresis (AGE); first PCR product with dot blot hybridization (DBH); nested PCR with AGE. Compared with culture, the sensitivity, specificity, and efficiency for first PCR with AGE were 71.8, 100 and 84.9% respectively; PCR with DBH gave results of 89.5, 96.3 and 92.6% respectively; the same values for nested PCR were 96.0, 97.2, and 96.5% respectively. Of these three methods, nested PCR gave excellent sensitivity and specificity with no significant difference (p = 0.727) from conventional culture. The storage of sputum on filter paper and storage at room temperature for 5 days had no apparent effect on the performance of nested PCR. We propose that this collection and storage method be considered for transporting sputum specimens from peripheral health centers or from the field; specimens may be sent by post to a central point for both culture and PCR analysis by trained technicians supervised in accordance with a well-established quality control system.     

Detection of IS6110 and HupB gene sequences of Mycobacterium tuberculosis and bovis in the aortic tissue of patients with Takayasu's arteritis

ABSTRACT: Takayasu's arteritis (TA) is a chronic inflammatory disease affecting the large arteries and their branches; its etiology is still unknown. In individuals suffering from TA, arterial inflammation progresses to stenosis and/or occlusion, leading to organ damage and affecting survival. Relation of TA with Mycobacterium tuberculosis has been known, but there have been only a few systematic studies focusing on this association. The IS6110 sequence identifies the Mycobacterium tuberculosis complex and the HupB establishes the differences between M. tuberculosis and M. bovis. Our objective was to search the presence of IS6110 and HupB genes in aorta of patients with TA. METHODS: We analyzed aorta tissues embedded in paraffin from 5760 autopsies obtained from our institution, we divided the selected samples as cases and controls; Cases: aortic tissues of individuals with Takayasu's arteritis. Control positive: aortic tissues (with tuberculosis disease confirmed) and control negative with other disease aortic (atherosclerosis). RESULTS: Of 181 selected aorta tissues, 119 fulfilled the corresponding criteria for TA, TB or atherosclerosis. Thus 33 corresponded to TA, 33 to tuberculosis (TB) and 53 to atherosclerosis. The mean age was 22?±?13, 41?±?19, and 57?±?10, respectively. IS6110 and HupB sequences were detected in 70% of TA tissues, 82% in tuberculosis, and in 32% with atherosclerosis. Important statistical differences between groups with TA, tuberculosis versus atherosclerosis (p?=?0.004 and 0.0001, respectively) were found. CONCLUSION: We identified a higher frequency of IS6110 and HupB genes in aortic tissues of TA patients. This data suggests that arterial damage could occur due to previous infection with M. tuberculosis.     

Simultaneous use of two PCR systems targeting IS6110 and MPB64 for confirmation of diagnosis of tuberculous lymphadenitis

PCR has emerged as a powerful technique for detection of various pathogens including Mycobacterium tuberculosis. In present study, eighty one samples of lymph node biopsies from clinically suspected cases of tuberculous lymphadenitis were examined for AFB, culture on L?wenstein Jensen medium and simultaneous use of two PCRs targeting IS6110 and MPB64. Positivity with M. tuberculosis culture and AFB was 13.6% and 28.4% respectively. All samples culture positive for nontuberculous mycobacteria were negative by both PCR systems. Higher proportion of positive results were observed with PCR targeting IS6110 by which 56 of 81 (69.1%) samples showed positive results as compared to PCR targeting MPB64 by which 39 of 81 (48.2 %) samples showed positive results. When combined, 63 out of 81 (77.8%) samples were detected positive for M. tuberculosis DNA. However, 7/81 (8.6 %) samples remained negative by IS6110 but positive by MPB64 method. Thus our data suggest that the use of one additional PCR (other than IS6110 system) can reduce false negativity of PCR results in the samples harboring zero copy of IS6110 element which is known to exist in Indian population.