Mutation screening of the F Ⅷ gene in 10 hemophilia A families

Objective To identify the F Ⅷ gene mutations of patients and suspected female carriers in 10 Hemophilia A (HA) families, and to guide the prenatal diagnosis. Methods PCR, denaturing high performance liquid chromatogramphy(DHPLC) and DNA sequencing technologies were applied to screen the FⅧ gene of 8 HA patients and 12 suspected female carriers in the 10 families. Linkage analysis was performed by using St 14 (DXS 52), intron 13 (CA)n and EX18/Bcl Ⅰ of the FⅧ gene in the HA families.In prenatal diagnosis, we screened the same mutation found in the patients. PCR-restriction fragment length polymorphism was applied to detect the new missense mutations of F Ⅷ gene in 100 unrelated healthy individuals to exclude the possibility of polymorphism. Results (1) Five missense mutations, 3 frameshift mutations, 2 nonsense mutations and 2 single nucleotide polymorphism(SNP) were identified in 10 the HA families. Among them, c. 878A＞G, c. 1015A＞G, c. 6870G＞T, c. 1282delA, c. 3072_3073insT, c. 4880_4881insA and c. 5000G＞A were novel mutations or polymorphism. No missense mutations c. 878A＞G, c.1015A＞G and c. 6870G＞T, were found in the 100 healthy unrelated controls. (2) Nine suspected female carriers were confirmed at the gene level. (3) X risk chromosome could be determined in 4 HA families by genetic linkage analysis. (4) Among the four fetuses for prenatal diagnosis, 2 were normal, 1 was carrier and the remaining 1 was a patient. Conclusion Six novel mutations, i. e. , c. 878A＞G, c. 1015A＞G, c.6870G＞T, c. 1282delA, c. 3072_3073insT and c. 4880_4881insA, were identified in this study. PCR,DHPLC and DNA sequencing could be used to screen the gene mutations of HA patients, to carry out carrier detection and prenatal diagnosis of HA families efficiently, by combining with restriction endonuclease analysis and genetic linkage analysis.     

Mutation screening of the F Ⅷ gene in 10 hemophilia A families

Objective To identify the F Ⅷ gene mutations of patients and suspected female carriers in 10 Hemophilia A (HA) families, and to guide the prenatal diagnosis. Methods PCR, denaturing high performance liquid chromatogramphy(DHPLC) and DNA sequencing technologies were applied to screen the FⅧ gene of 8 HA patients and 12 suspected female carriers in the 10 families. Linkage analysis was performed by using St 14 (DXS 52), intron 13 (CA)n and EX18/Bcl Ⅰ of the FⅧ gene in the HA families.In prenatal diagnosis, we screened the same mutation found in the patients. PCR-restriction fragment length polymorphism was applied to detect the new missense mutations of F Ⅷ gene in 100 unrelated healthy individuals to exclude the possibility of polymorphism. Results (1) Five missense mutations, 3 frameshift mutations, 2 nonsense mutations and 2 single nucleotide polymorphism(SNP) were identified in 10 the HA families. Among them, c. 878A＞G, c. 1015A＞G, c. 6870G＞T, c. 1282delA, c. 3072_3073insT, c. 4880_4881insA and c. 5000G＞A were novel mutations or polymorphism. No missense mutations c. 878A＞G, c.1015A＞G and c. 6870G＞T, were found in the 100 healthy unrelated controls. (2) Nine suspected female carriers were confirmed at the gene level. (3) X risk chromosome could be determined in 4 HA families by genetic linkage analysis. (4) Among the four fetuses for prenatal diagnosis, 2 were normal, 1 was carrier and the remaining 1 was a patient. Conclusion Six novel mutations, i. e. , c. 878A＞G, c. 1015A＞G, c.6870G＞T, c. 1282delA, c. 3072_3073insT and c. 4880_4881insA, were identified in this study. PCR,DHPLC and DNA sequencing could be used to screen the gene mutations of HA patients, to carry out carrier detection and prenatal diagnosis of HA families efficiently, by combining with restriction endonuclease analysis and genetic linkage analysis.     

10个甲型血友病家系FⅧ基因突变分析

目的 分析10个家系中甲型血友病(hemophilia A,HA)患者及女性疑似携带者FⅧ基因突变,并指导产前诊断.方法 应用聚合酶链反应(polymerase chin reaction,PCR)、变性高效液相色谱技术(denaturing high performance liquid chromatogramphy,DHPLC)和DNA测序技术对10个家系中8例HA患者、12名女性疑似携带者的FⅧ基因进行突变检测,并应用St14(DXS 52)、13(CA)n、EX18/BclⅠ3个遗传标记位点对HA家系进行连锁分析.产前诊断检测已知突变位点.针对未见报道的新突变,用限制性内切酶进行分析,同时与100名表型正常的无关个体进行比较,排除多态性.结果 (1)在10个家系中发现5例错义突变、3例移码突变、2例无义突变和2个单核苷酸多态性(single nucleotide polymorphism,SNP)位点.错义突变c.878A＞G、c.1015A＞G和c.6870G＞T,移码突变c.1282delA、c3072_3073insT和c.4880_4881insA以及SNP位点c.5000 G＞A均为国际血友病网站和人类突变数据库未记载的突变或多态.在100名正常人中未检测到错义突变c.878A＞G、c.1015A＞G和c.6870G＞T.(2)在12名女性疑似携带者中,基困水平确诊9例为HA携带者,3名为正常人.(3)遗传连锁分析为4个家系提供了X风险染色体的有效信息.(4)产前诊断结果显示2例胎儿正常、1例HA携带者和1例HA患者.结论 发现c.878 A＞G、c.1015A＞G、c.6870G＞T、c.1282delA、c.3072 3073insT及c.4880_4881insA共6种能引起甲型血友病的新突变;PCR、DHPLC和DNA测序技术可有效检测甲型血友病患者基因突变,而联合限制性内切酶分析和遗传连锁分析能快速筛查HA携带者,进行有效的产前诊断.

Abstract：

Objective To identify the F Ⅷ gene mutations of patients and suspected female carriers in 10 Hemophilia A (HA) families, and to guide the prenatal diagnosis. Methods PCR, denaturing high performance liquid chromatogramphy(DHPLC) and DNA sequencing technologies were applied to screen the FⅧ gene of 8 HA patients and 12 suspected female carriers in the 10 families. Linkage analysis was performed by using St 14 (DXS 52), intron 13 (CA)n and EX18/Bcl Ⅰ of the FⅧ gene in the HA families.In prenatal diagnosis, we screened the same mutation found in the patients. PCR-restriction fragment length polymorphism was applied to detect the new missense mutations of F Ⅷ gene in 100 unrelated healthy individuals to exclude the possibility of polymorphism. Results (1) Five missense mutations, 3 frameshift mutations, 2 nonsense mutations and 2 single nucleotide polymorphism(SNP) were identified in 10 the HA families. Among them, c. 878A＞G, c. 1015A＞G, c. 6870G＞T, c. 1282delA, c. 3072_3073insT, c. 4880_4881insA and c. 5000G＞A were novel mutations or polymorphism. No missense mutations c. 878A＞G, c.1015A＞G and c. 6870G＞T, were found in the 100 healthy unrelated controls. (2) Nine suspected female carriers were confirmed at the gene level. (3) X risk chromosome could be determined in 4 HA families by genetic linkage analysis. (4) Among the four fetuses for prenatal diagnosis, 2 were normal, 1 was carrier and the remaining 1 was a patient. Conclusion Six novel mutations, i. e. , c. 878A＞G, c. 1015A＞G, c.6870G＞T, c. 1282delA, c. 3072_3073insT and c. 4880_4881insA, were identified in this study. PCR,DHPLC and DNA sequencing could be used to screen the gene mutations of HA patients, to carry out carrier detection and prenatal diagnosis of HA families efficiently, by combining with restriction endonuclease analysis and genetic linkage analysis.     

血友病甲基因分析技术的改进及其在产前诊断中的应用

目的对血友病甲基因分析技术进行改进并应用于携带者检查和产前诊断。方法长距离聚合酶链反应方法直接检测凝血因子Ⅷ第22内含子倒位,对非倒位家系用FⅧ基因内限制酶切位点XbaⅠ、HindⅢ、二核苷酸重复序列多态性位点STR13和STR22,以及基因外可变数目串联重复序列DXS52(St14)位点进行基因连锁分析。结果52个家系共检出71位携带者。21个家系为第22内含子倒位,28个家系经连锁分析得到明确诊断,3个家系无法诊断,可诊断家系占94.2%。为18个家系做胎儿产前诊断,其中10例诊断为血友病甲胎儿;诊断7例正常男胎和1例携带者女胎,随访1年发育正常。结论应用长距离聚合酶链反应和多位点基因连锁分析技术可以快速有效地进行血友病甲携带者检查和产前诊断。     

甲型血友病家系的直接和间接基因诊断

目的该研究针对温州地区甲型血友病(HA)家系,首先进行直接基因诊断,然后根据可变数目串联重复序列(VNTR)多态性、短串联重复序列(STR)多态性和限制性片段长度多态性(RFLP)进行间接基因诊断,为基于HA症状前、携带者基因诊断结果的遗传咨询和生育指导提供依据。方法针对HA先证者及其有关家系成员,首先采用倒位位移PCR(IS-PCR)进行凝血因子Ⅷ(FⅧ)inv22、del22、dup22、inv1的检测。然后进行单体型基因连锁分析。采用PCR检测FⅧ基因外的DXS52(St14)位点的VNTR多态性,检测FⅧ基因外的DXS15(CA)n、DXS9901(GT)n、DXS1073(GT)n位点和内含子1(GT)n、13(CA)n、22(GT)n(AG)n、24(GT)n位点的STR多态性并经毛细管电泳确证。另外采用PCR产物限制酶切检测FⅧ基因的内含子18、19、22位点的RFLP多态性。结果以2个HA家系为例报道研究结果。家系三的先证者为远端Inv22患者,先证者母亲为远端inv22携带者,先证者父亲为正常者。先证者、先证者母亲、先证者父亲均未发生del22或dup22,并且均未发生inv1。家系五先证者外婆肯定不是携带者,先证者的X染色体来自外公,但已知外公不是患者,那么按照最大风险估计,母亲的那条来自外公的X染色体在外公生殖细胞中FⅧ基因发生了突变,因此母亲是携带者。结论该研究的HA家系的直接和间接基因诊断,特别是对症状前男孩的诊断、对未曾有患病后代的女性携带者的检出,具有非常重要的实际意义,可以为遗传咨询和生育指导提供可靠依据。     

X染色体STR荧光复合扩增体系的建立及多态性

Objective To learn about the genetic diversity of X-STR and to collect data of population genetics, the six X-STR loci were tested. Methods DXS6801、 DXS9902、 DXS6809、 DXS6803、 DXS6804 and DXS6799 were amplified in a single PCR reaction. PCR products were analyzed using capillary electrophoresis and ABI prism 3100 Genetic Analyzer, with GeneMapper ID 3. 1 Analysis Software. Results Allele typing with the systems was successful for all of six loci. When 202 unrelated male and 62 unrelated female individuals from Guangdong Han population were tested, 8,6, 11, 10,6 and 9 alleles were detected for DXS6801, DXS9902, DXS6809, DXS6803, DXS6804 and DXS6799, respectively. Polymorphism information content is 0. 662 3～0. 837 6. Power of discrimination in females is 0. 824 2～0. 951 1. Mean exclusion chance for X-STR in standard trios with daughters is 0. 594 9～0. 817 4. Conclusion The six loci in the multiplex system provide high polymorphism information for forensic identification and paternity testing, particularly for difficult paternity deficiency cases     

X染色体STR荧光复合扩增体系的建立及多态性

Objective To learn about the genetic diversity of X-STR and to collect data of population genetics, the six X-STR loci were tested. Methods DXS6801、 DXS9902、 DXS6809、 DXS6803、 DXS6804 and DXS6799 were amplified in a single PCR reaction. PCR products were analyzed using capillary electrophoresis and ABI prism 3100 Genetic Analyzer, with GeneMapper ID 3. 1 Analysis Software. Results Allele typing with the systems was successful for all of six loci. When 202 unrelated male and 62 unrelated female individuals from Guangdong Han population were tested, 8,6, 11, 10,6 and 9 alleles were detected for DXS6801, DXS9902, DXS6809, DXS6803, DXS6804 and DXS6799, respectively. Polymorphism information content is 0. 662 3～0. 837 6. Power of discrimination in females is 0. 824 2～0. 951 1. Mean exclusion chance for X-STR in standard trios with daughters is 0. 594 9～0. 817 4. Conclusion The six loci in the multiplex system provide high polymorphism information for forensic identification and paternity testing, particularly for difficult paternity deficiency cases     

Clinical and molecular genetic analysis for 7 patients from 5 pedigrees with 17α-hydroxylase/17, 20 lyase deficiency

Objective To investigate the clinical and genetic characteristics of 7 patients from 5 families with 17α-hydroxylase/17, 20 lyase deficiency (17OHD) and the CYP17A1 mutation in Chinese. Methods Clinical features and laboratory data were collected from 5 families with 17OHD. PCR direct sequencing was performed to screen the mutation of CYP17A1 gene of the patients. Polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) and sequencing were performed to screen the mutations of CYP17A1 gene in 288 healthy individuals from Shandong province. Results Seven patients (5 of them were 46, XX; 2 were 46, XY) had typical clinical presentation of sexual infantilism, hypertension and hypokalemia. Hormone profile indicated decreased plasma cotisol and sex hormones, and elevated blood adrenocorticotrophic hormone (ACTH). TAC329AA and H373L in exon 6 and D487_ F489del in exon 8 were identified from the patients. One heterozygote for D487_F489del was identified in 288 healthy controls. Conclusion The TAC329AA and D487_F489del of the CYP17A1 gene were the most frequent mutations in Chinese with 17OHD. There might be certain frequency of heterozygotes for D487_ F489del in Chinese population.     

Clinical and molecular genetic analysis for 7 patients from 5 pedigrees with 17α-hydroxylase/17, 20 lyase deficiency

Objective To investigate the clinical and genetic characteristics of 7 patients from 5 families with 17α-hydroxylase/17, 20 lyase deficiency (17OHD) and the CYP17A1 mutation in Chinese. Methods Clinical features and laboratory data were collected from 5 families with 17OHD. PCR direct sequencing was performed to screen the mutation of CYP17A1 gene of the patients. Polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) and sequencing were performed to screen the mutations of CYP17A1 gene in 288 healthy individuals from Shandong province. Results Seven patients (5 of them were 46, XX; 2 were 46, XY) had typical clinical presentation of sexual infantilism, hypertension and hypokalemia. Hormone profile indicated decreased plasma cotisol and sex hormones, and elevated blood adrenocorticotrophic hormone (ACTH). TAC329AA and H373L in exon 6 and D487_ F489del in exon 8 were identified from the patients. One heterozygote for D487_F489del was identified in 288 healthy controls. Conclusion The TAC329AA and D487_F489del of the CYP17A1 gene were the most frequent mutations in Chinese with 17OHD. There might be certain frequency of heterozygotes for D487_ F489del in Chinese population.     

Clinical and molecular genetic analysis for 7 patients from 5 pedigrees with 17α-hydroxylase/17, 20 lyase deficiency

Objective To investigate the clinical and genetic characteristics of 7 patients from 5 families with 17α-hydroxylase/17, 20 lyase deficiency (17OHD) and the CYP17A1 mutation in Chinese. Methods Clinical features and laboratory data were collected from 5 families with 17OHD. PCR direct sequencing was performed to screen the mutation of CYP17A1 gene of the patients. Polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) and sequencing were performed to screen the mutations of CYP17A1 gene in 288 healthy individuals from Shandong province. Results Seven patients (5 of them were 46, XX; 2 were 46, XY) had typical clinical presentation of sexual infantilism, hypertension and hypokalemia. Hormone profile indicated decreased plasma cotisol and sex hormones, and elevated blood adrenocorticotrophic hormone (ACTH). TAC329AA and H373L in exon 6 and D487_ F489del in exon 8 were identified from the patients. One heterozygote for D487_F489del was identified in 288 healthy controls. Conclusion The TAC329AA and D487_F489del of the CYP17A1 gene were the most frequent mutations in Chinese with 17OHD. There might be certain frequency of heterozygotes for D487_ F489del in Chinese population.     

联合运用St14(DXS52)位点VNTR和 FⅧ基因内的(CA)n重复多态性诊断甲型血友病

目的　提高甲型血友病 (hemophilia A,HA)家系成员基因诊断及产前基因诊断的准确性和可诊断率。方法　采用 St14 (DXS5 2 )位点的可变串联重复序列和 F 基因第 13内含子的 (CA) n重复多态性连锁分析对 HA家系进行间接基因诊断。结果　单用上述 2个多态位点中的 1个对 9个 HA家系进行连锁分析 ,可诊断率均为 6 6 .7% ,联合 2个多态位点 ,可诊断率则提高到 88.9% ,完成了 4个家系的产前基因诊断 ,并监测到 1例单用 St14位点的可变串联重复序列多态连锁分析可能发生的产前诊断的误诊。结论联合采用上述 2个多态位点可以对近 90 %的 HA家系作出快速、准确的基因诊断和产前基因诊断。     

Linkage analysis of the fragile X syndrome using a new DNA marker U6.2 defining locus DXS304.

A new RFLP marker U6.2 defining the locus DXS304 was recently mapped to the distal long arm of the X chromosome. In the present study we report the results of genetic linkage analysis of 13 fragile X [fra(X)] families that were informative for the new marker. Analysis of the recombinants for F9-FRAXA, DXS105-FRAXA, DXS98-FRAXA, DXS52-FRAXA, DXS15-FRAXA, and F8C-FRAXA, places DXS304 distal and near to the FRAXA locus. Combined with results from previous studies, our results support the order Xcen.-F9-DXS105-DXS98-FRAXA-DXS304-DXS5 2-DXS15-F8C-Xqter. Close linkage was observed between DXS304 and the disease locus with a peak lod score of 5.12 at theta = 0.04 from the present study and, with a peak lod score of 17.45 at theta = 0.035 when our data are combined with published data from 2 other studies. The present study confirms that U6.2 is useful for prenatal diagnosis and carrier testing in families affected by fra(X) syndrome.     

Recombination between the factor VIII gene and the DXS52 locus gives the most probable genetic order as centromere-fra(X)-DXS15-DXS52-F8C-telomere

The linkage relationship between the factor VIII gene (F8C) and the DXS52 locus was examined in 8 families. Two recombinations were identified in 35 informative meioses (Zmax = 5.67; theta = 0.05), one in a family with hemophilia A, the other in a family with the fra(X) syndrome. Based on the latter recombination, the most probable order of loci was determined to be centromere-fra(X)-DXS15-DXS52-F8C-telomere. When these data are added to those reported previously the most probable genetic distance between F8C and DXS52 is 3 cM (Z = 14.62). Identification of these and other recombinations suggests that the use of DXS52 as a genetic marker for carrier detection and prenatal diagnosis of hemophilia A has an error rate between 3-5%.     

Multipoint linkage of 9 anonymous probes to HPRT, factor 9, and fragile X

We have analyzed the segregation of restriction fragment length polymorphisms (RFLPs) associated with 9 anonymous probes detecting loci DXS10, DXS15, DXS19, DXS37, DXS51, DXS52, DXS98, DXS99, and DXS100 and probes for HPRT and F9 in a set of 40 families segregating fragile X (fra(X]. Using two-point and multipoint analysis, we have established their relative genetic locations. The results indicate that DXS99 and DXS10, unlike previous reports, are not tightly linked to F9. A new locus was found to map within the F9 - fra(X) region. DXS98 showed 6% recombination with fra(X) and appeared to be the closest locus to fra(X). These results will be useful for mapping the relative position of newly defined X probes in this region and for future genetic studies of families with fra(X), hemophilia B, or Lesch-Nyhan mutations.     

Refining the genetic location of the gene for X linked hydrocephalus within Xq28.

The most common inherited form of hydrocephalus, X linked hydrocephalus (HSAS), is characterised by mental retardation, adducted thumbs, and spastic paraplegia. Genetic analysis has mapped the locus for HSAS to subchromosomal band Xq28 within a region of approximately 2 megabases of DNA. In order to refine the location of the disease gene we have conducted genetic linkage analysis with Xq28 marker loci in four additional HSAS families. A lod score of 4.26 with polymorphic marker DXS52 (St14) confirms the linkage of HSAS to Xq28. Identification of a recombination event between the HSAS gene and Xq28 loci F8C and DXS605 (2-19) reduces the size of the interval likely to contain the disease locus to about 1.5 megabases, the distance between DXS605 and DXS52. The locus for neural cell adhesion molecule, L1CAM, maps within this interval and therefore represents a candidate gene for HSAS.     

Emery-Dreifuss muscular dystrophy: linkage to markers in distal Xq28.

Emery-Dreifuss muscular dystrophy (EMD) is characterised by (1) early contractures of the Achilles tendons, elbows, and postcervical muscles, (2) slowly progressive muscle wasting and weakness with a predominantly humeroperoneal distribution in the early stages, and (3) cardiomyopathy with conduction defects and risk of sudden death. Inheritance is usually X linked recessive but can be autosomal dominant. Family linkage studies have mapped X linked EMD to the distal long arm of the X chromosome but precise genetic localisation has been hampered by the rarity of this condition. We report three new families with X linked Emery-Dreifuss muscular dystrophy studied with DNA markers from Xq27-qter and three previously published families typed for additional markers. No recombination was observed with the red/green cone pigment locus, RGCP (lod score, Z = 2.46), the factor VIII coagulant gene locus, F8C (Z = 6.39), or with DXS115 (Z = 4.94). Two recombinants were observed which mapped EMD distal to DXS15 (DX13) and DXS52 (St14) respectively. Multipoint linkage analysis gave odds exceeding 200:1 for EMD being distal to these markers. A multipoint analysis incorporating published data gave the map cen-DXS304-9cM-DXS15-3cM-DXS52-2 cM-(RGCP,EMD)-3cM-F8C-2cM-DXS115 with odds of 120:1 in favour of a location for EMD between DXS52 and F8C as compared to the next best position distal to F8C.     

Extragenic factor IX gene RFLP is useful for detecting carriers of Japanese hemophilia B

Seventy-eight X chromosomes from 25 normal Japanese subjects and 22 family members with hemophilia B (coagulation factor IX deficiency) were examined with an extragenic factor IX DNA probe, pX58dIIIc at DXS99 locus. In contrast to the previously described nonpolymorphic RFLPs in the factor IX gene, DXS99 locus RFLP produced by SacI digestion was detected among those Japanese subjects with allelic frequencies of 0.48 and 0.52. The estimated heterozygosity rate of this extragenic RFLP among Japanese females was about 50%. The study of hemophilia B family members showed that DXS99 locus RFLP was informative in 9 out of 13 families tested (69.2%). No recombination events between the factor IX gene locus (F9) and DXS99 locus have been noted among nine families analyzed. DXS99 SacI RFLP is a useful gene indicator of carrier-ship of hemophilia B.     

Linkage in fragile X families of three distal flanking markers: ST14, DX13, and F8.

The use of linked DNA markers and linkage analysis in the fragile X [fra(X)] syndrome allows for improved genetic counseling and prenatal diagnosis. In order to provide the most accurate information, it is important to determine the order and location and position of flanking markers. Conflicting results have been reported for the order of 3 DNA markers distal to the fra(X) locus. We analyzed the linkage relationships of the distal markers ST14 (DXS52), DX13 (DXS15), and F8 (F8C) in 102 fra(X) families. The results indicated that the 3 DNA markers were closely linked to one another and mapped approximately 11 to 15% recombination units away from the fra(X) locus. The most likely order was fra(X)-DXS52-DXS15-F8. The order fra(X)-DXS52-F8 and 728 times more likely than the order fra(X)-F8-DXS52. One family showed a probable double recombinant: in one individual there was recombination between fra(X)-DXS52 and between DXS52-F8. The low probability of this occurring, 0.3%, raises the possibility of an alternate chromosome arrangement or an unusual recombinant mechanism in some individuals.