The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Tracey E. Madgett - One of the best experts on this subject based on the ideXlab platform.
-
Rapid RHD Zygosity Determination Using Digital PCR
Clinical chemistry, 2017Co-Authors: Kelly A. Sillence, Amr J Halawani, Wajnat A Tounsi, Kirsty A Clarke, Michele Kiernan, Tracey E. Madgett, Neil D. AventAbstract:Paternal Zygosity testing is used for determining homo- or hemiZygosity of RHD in pregnancies that are at a risk of hemolytic disease of the fetus and newborn. At present, this is achieved by using real-time PCR or the Rhesus box PCR, which can be difficult to interpret and unreliable, particularly for black African populations. DNA samples extracted from 53 blood donors were analyzed using 2 multiplex reactions for RHD-specific targets against a reference (AGO1)2 to determine gene dosage by digital PCR. Results were compared with serological data, and the correct genotype for 2 discordant results was determined by long-range PCR (LR-PCR), next-generation sequencing, and conventional Sanger sequencing. The results showed clear and reliable determination of RHD Zygosity using digital PCR and revealed that 4 samples did not match the serologically predicted genotype. Sanger sequencing and long-range PCR followed by next-generation sequencing revealed that the correct genotypes for samples 729M and 351D, which were serologically typed as R1R2 (DCe/DcE), were R2r' (DcE/dCe) for 729M and R1r″ (DCe/dcE), R0ry (Dce/dCE), or RZr (DCE/dce) for 351D, in concordance with the digital PCR data. Digital PCR provides a highly accurate method to rapidly define blood group Zygosity and has clinical application in the analysis of Rh phenotyped or genotyped samples. The vast majority of current blood group genotyping platforms are not designed to define Zygosity, and thus, this technique may be used to define paternal RH Zygosity in pregnancies that are at a risk of hemolytic disease of the fetus and newborn and can distinguish between homo- and hemizygous RHD-positive individuals. © 2017 American Association for Clinical Chemistry.
-
rhd and rhce variant and Zygosity genotyping via multiplex ligation dependent probe amplification
Transfusion, 2013Co-Authors: Tracey E. Madgett, Barbera Veldhuisen, Remco Jonkers, Martin Lodén, Lonneke HaerwigmanAbstract:Background The presence of a D variant may hamper correct serologic D typing, which may result in D immunization. D variants can be determined via RHD genotyping. However, a convenient single assay to identify D variants is still lacking. We developed and evaluated a multiplex ligation–dependent probe amplification (MLPA) assay to determine clinically relevant RHD and RHCE variant alleles and RHD Zygosity. Study design and methods We analyzed 236 cases (73 normal and 163 selected samples) with the RH-MLPA assay, which is able to determine 79 RHD and 17 RHCE variant alleles and RHD Zygosity. To confirm the results, mutations were verified by RHD and/or RHCE exon–specific sequencing and RHD Zygosity was verified by quantitative real-time polymerase chain reaction (PCR) for 18 cases. Results In 99% of the cases, the RH-MLPA assay correctly determined whether a person carried only wild-type RHD and RHCE alleles (n = 69) or (a) variant RHD allele(s) and/or (a) variant RHCE allele(s) (n = 164). In only three cases, including two new RHD variant alleles, the variant allele was not identified, due to lack of detecting probes. These were RHD*DCS2, a new partial RHD allele, RHD*525T (Phe175Leu), and a new D– null allele, RHD*443G (Thr148Arg). All RHD (n = 175) and RHCE variant alleles (n = 79) indicated by the RH-MLPA assay were confirmed by sequencing. RHD Zygosity was confirmed by quantitative PCR. Two hematopoietic chimeras were recognized. Conclusion The RH-MLPA genotyping assay is a fast, easy, and reliable method to determine almost all clinically relevant RHD and RHCE variant alleles, RHD Zygosity, and RHD+/RHD– chimeras in blood donors, blood recipients, and pregnant women.
-
RHD and RHCE variant and Zygosity genotyping via multiplex ligation–dependent probe amplification
Transfusion, 2012Co-Authors: Lonneke Haer-wigman, Tracey E. Madgett, Neil D. Avent, Barbera Veldhuisen, Remco Jonkers, Martin Lodén, Masja De Haas, C. Ellen Van Der SchootAbstract:Background The presence of a D variant may hamper correct serologic D typing, which may result in D immunization. D variants can be determined via RHD genotyping. However, a convenient single assay to identify D variants is still lacking. We developed and evaluated a multiplex ligation–dependent probe amplification (MLPA) assay to determine clinically relevant RHD and RHCE variant alleles and RHD Zygosity. Study design and methods We analyzed 236 cases (73 normal and 163 selected samples) with the RH-MLPA assay, which is able to determine 79 RHD and 17 RHCE variant alleles and RHD Zygosity. To confirm the results, mutations were verified by RHD and/or RHCE exon–specific sequencing and RHD Zygosity was verified by quantitative real-time polymerase chain reaction (PCR) for 18 cases. Results In 99% of the cases, the RH-MLPA assay correctly determined whether a person carried only wild-type RHD and RHCE alleles (n = 69) or (a) variant RHD allele(s) and/or (a) variant RHCE allele(s) (n = 164). In only three cases, including two new RHD variant alleles, the variant allele was not identified, due to lack of detecting probes. These were RHD*DCS2, a new partial RHD allele, RHD*525T (Phe175Leu), and a new D– null allele, RHD*443G (Thr148Arg). All RHD (n = 175) and RHCE variant alleles (n = 79) indicated by the RH-MLPA assay were confirmed by sequencing. RHD Zygosity was confirmed by quantitative PCR. Two hematopoietic chimeras were recognized. Conclusion The RH-MLPA genotyping assay is a fast, easy, and reliable method to determine almost all clinically relevant RHD and RHCE variant alleles, RHD Zygosity, and RHD+/RHD– chimeras in blood donors, blood recipients, and pregnant women.
William R. True - One of the best experts on this subject based on the ideXlab platform.
-
Determining Zygosity in the Vietnam Era Twin Registry: an approach using questionnaires.
Clinical genetics, 2008Co-Authors: Seth A. Eisen, Jack Goldberg, Rosalind J. Neuman, John P. Rice, William R. TrueAbstract:The Vietnam Era Twin Registry (VETR) is a registry of 7375 American male veteran twin pairs born between 1939 and 1955 who served in the armed forces of the United States between 1964 and 1975. Optimal use of registry data requires the determination of Zygosity. Two approaches are available: analysis of blood genetic marker systems and responses of twins to questions about sibling similarity. Zygosity for the VETR was determined using the questionnaire technique supplemented with blood group typing data abstracted from military records. After comparing four alternative Zygosity assignment methods, a logistic regression technique which uses discriminating variables based on race was selected. The approach is similar to that described by Magnus et al. (1983) in their study of Norwegian twins, suggesting that questionnaire responses are independent of nationality and reinforcing the reliability of the questionnaire method for Zygosity ascertainment.
-
Self-Reported Zygosity and the equal-environments assumption for psychiatric disorders in the Vietnam Era Twin Registry.
Behavior genetics, 2000Co-Authors: Hong Xian, Jack Goldberg, Andrew C. Heath, Seth A. Eisen, William R. True, Jeffrey F. Scherrer, Michael J. Lyons, Ming T. TsuangAbstract:The equal-environments assumption (EEA) in twin studies of psychiatric disorders assumes that the family environment which contributes to risk for a disorder is equally correlated between monozygotic (MZ) and dizygotic (DZ) twin pairs. In a study of psychiatric disorders in female twins, Kendler and colleagues (1993) have demonstrated the utility of a test of the EEA which includes a specified family environmental factor defined by using measures of perceived Zygosity. We tested the EEA assumption among 3155 male—male twin pair members of the Vietnam Era Twin Registry for the following DSM-III-R lifetime disorders: alcohol dependence, marijuana dependence, any illicit drug dependence, nicotine dependence, major depression, and posttraumatic stress disorder. The majority of MZ (81.6%; n = 1593) and DZ (90.2%; n = 1086) twin pairs agreed with the investigator's assigned Zygosity. The best-fitting model for each of these disorders did not allow for a specified family environmental influence. These results support the usefulness of perceived Zygosity in tests of the EEA. In male twin pairs, perceived Zygosity has little impact on twin similarity for common psychiatric disorders.
Seth A. Eisen - One of the best experts on this subject based on the ideXlab platform.
-
Determining Zygosity in the Vietnam Era Twin Registry: an approach using questionnaires.
Clinical genetics, 2008Co-Authors: Seth A. Eisen, Jack Goldberg, Rosalind J. Neuman, John P. Rice, William R. TrueAbstract:The Vietnam Era Twin Registry (VETR) is a registry of 7375 American male veteran twin pairs born between 1939 and 1955 who served in the armed forces of the United States between 1964 and 1975. Optimal use of registry data requires the determination of Zygosity. Two approaches are available: analysis of blood genetic marker systems and responses of twins to questions about sibling similarity. Zygosity for the VETR was determined using the questionnaire technique supplemented with blood group typing data abstracted from military records. After comparing four alternative Zygosity assignment methods, a logistic regression technique which uses discriminating variables based on race was selected. The approach is similar to that described by Magnus et al. (1983) in their study of Norwegian twins, suggesting that questionnaire responses are independent of nationality and reinforcing the reliability of the questionnaire method for Zygosity ascertainment.
-
Self-Reported Zygosity and the equal-environments assumption for psychiatric disorders in the Vietnam Era Twin Registry.
Behavior genetics, 2000Co-Authors: Hong Xian, Jack Goldberg, Andrew C. Heath, Seth A. Eisen, William R. True, Jeffrey F. Scherrer, Michael J. Lyons, Ming T. TsuangAbstract:The equal-environments assumption (EEA) in twin studies of psychiatric disorders assumes that the family environment which contributes to risk for a disorder is equally correlated between monozygotic (MZ) and dizygotic (DZ) twin pairs. In a study of psychiatric disorders in female twins, Kendler and colleagues (1993) have demonstrated the utility of a test of the EEA which includes a specified family environmental factor defined by using measures of perceived Zygosity. We tested the EEA assumption among 3155 male—male twin pair members of the Vietnam Era Twin Registry for the following DSM-III-R lifetime disorders: alcohol dependence, marijuana dependence, any illicit drug dependence, nicotine dependence, major depression, and posttraumatic stress disorder. The majority of MZ (81.6%; n = 1593) and DZ (90.2%; n = 1086) twin pairs agreed with the investigator's assigned Zygosity. The best-fitting model for each of these disorders did not allow for a specified family environmental influence. These results support the usefulness of perceived Zygosity in tests of the EEA. In male twin pairs, perceived Zygosity has little impact on twin similarity for common psychiatric disorders.
Jack Goldberg - One of the best experts on this subject based on the ideXlab platform.
-
Determining Zygosity in the Vietnam era twin registry: an update.
Twin research and human genetics : the official journal of the International Society for Twin Studies, 2010Co-Authors: Christopher W. Forsberg, Jack Goldberg, Jennifer L. Sporleder, Nicholas L. SmithAbstract:Our work assessed the accuracy of the original Zygosity classification in the Vietnam Era Twin (VET) Registry using new information from DNA markers on a subset of participants. We then constructed an updated Zygosity classification algorithm. The VET Registry includes 7,375 male-male twin pairs who served in the military during the Vietnam era. During the mid-1980s 4,774 twin pairs completed a Zygosity questionnaire of 20 items. Additionally, military record information, including blood group, was available. Items from the Zygosity questionnaire and blood group were used in the original Zygosity classification. Between 1990-2009 DNA was obtained from 612 twin pairs and concordance between co-twins was used to classify Zygosity. Next logistic regression was used to construct predicted probabilities of Zygosity using items from the Zygosity questionnaire with this subsample. All twins were reclassified according to the new Zygosity prediction model and compared with the original Zygosity assignment. The original and new predicted probabilities of Zygosity were highly correlated (r = 0.962) and concordance for the classification of Zygosity was similarly high (kappa = 0.936). Errors in the original Zygosity assignment were primarily due to monozygotic twins that were misclassified as dizygotic based on military record blood group data. Removing the military record blood group data markedly improved the accuracy of the original classification. Zygosity assignment based on a Zygosity questionnaire was highly predictive of DNA-based Zygosity. Augmentation of such a Zygosity classification from administrative data, military records, or other records, should be done with caution.
-
Determining Zygosity in the Vietnam Era Twin Registry: an approach using questionnaires.
Clinical genetics, 2008Co-Authors: Seth A. Eisen, Jack Goldberg, Rosalind J. Neuman, John P. Rice, William R. TrueAbstract:The Vietnam Era Twin Registry (VETR) is a registry of 7375 American male veteran twin pairs born between 1939 and 1955 who served in the armed forces of the United States between 1964 and 1975. Optimal use of registry data requires the determination of Zygosity. Two approaches are available: analysis of blood genetic marker systems and responses of twins to questions about sibling similarity. Zygosity for the VETR was determined using the questionnaire technique supplemented with blood group typing data abstracted from military records. After comparing four alternative Zygosity assignment methods, a logistic regression technique which uses discriminating variables based on race was selected. The approach is similar to that described by Magnus et al. (1983) in their study of Norwegian twins, suggesting that questionnaire responses are independent of nationality and reinforcing the reliability of the questionnaire method for Zygosity ascertainment.
-
Self-Reported Zygosity and the equal-environments assumption for psychiatric disorders in the Vietnam Era Twin Registry.
Behavior genetics, 2000Co-Authors: Hong Xian, Jack Goldberg, Andrew C. Heath, Seth A. Eisen, William R. True, Jeffrey F. Scherrer, Michael J. Lyons, Ming T. TsuangAbstract:The equal-environments assumption (EEA) in twin studies of psychiatric disorders assumes that the family environment which contributes to risk for a disorder is equally correlated between monozygotic (MZ) and dizygotic (DZ) twin pairs. In a study of psychiatric disorders in female twins, Kendler and colleagues (1993) have demonstrated the utility of a test of the EEA which includes a specified family environmental factor defined by using measures of perceived Zygosity. We tested the EEA assumption among 3155 male—male twin pair members of the Vietnam Era Twin Registry for the following DSM-III-R lifetime disorders: alcohol dependence, marijuana dependence, any illicit drug dependence, nicotine dependence, major depression, and posttraumatic stress disorder. The majority of MZ (81.6%; n = 1593) and DZ (90.2%; n = 1086) twin pairs agreed with the investigator's assigned Zygosity. The best-fitting model for each of these disorders did not allow for a specified family environmental influence. These results support the usefulness of perceived Zygosity in tests of the EEA. In male twin pairs, perceived Zygosity has little impact on twin similarity for common psychiatric disorders.
Weiping Tang - One of the best experts on this subject based on the ideXlab platform.
-
effective noninvasive Zygosity determination by maternal plasma target region sequencing
PLOS ONE, 2013Co-Authors: Jing Zheng, Jing Guo, Yuan Wei, Chunlei Zhang, Haojun Jiang, Ling Pan, Weiping Tang, Weiwei Xie, Hongyun Zhang, Yangyu ZhaoAbstract:Background Currently very few noninvasive molecular genetic approaches are available to determine Zygosity for twin pregnancies in clinical laboratories. This study aimed to develop a novel method to determine Zygosity by using maternal plasma target region sequencing.
-
Effective noninvasive Zygosity determination by maternal plasma target region sequencing.
PloS one, 2013Co-Authors: Jing Zheng, Jing Guo, Yuan Wei, Chunlei Zhang, Haojun Jiang, Ling Pan, Weiping TangAbstract:Currently very few noninvasive molecular genetic approaches are available to determine Zygosity for twin pregnancies in clinical laboratories. This study aimed to develop a novel method to determine Zygosity by using maternal plasma target region sequencing. We constructed a statistic model to calculate the possibility of each Zygosity type using likelihood ratios ( Li ) and empirical dynamic thresholds targeting at 4,524 single nucleotide polymorphisms (SNPs) loci on 22 autosomes. Then two dizygotic (DZ) twin pregnancies,two monozygotic (MZ) twin pregnancies and two singletons were recruited to evaluate the performance of our novel method. Finally we estimated the sensitivity and specificity of the model in silico under different cell-free fetal DNA (cff-DNA) concentration and sequence depth. We obtained 8.90 Gbp sequencing data on average for six clinical samples. Two samples were classified as DZ with L values of 1.891 and 1.554, higher than the dynamic DZ cut-off values of 1.162 and 1.172, respectively. Another two samples were judged as MZ with 0.763 and 0.784 of L values, lower than the MZ cut-off values of 0.903 and 0.918. And the rest two singleton samples were regarded as MZ twins, with L values of 0.639 and 0.757, lower than the MZ cut-off values of 0.921 and 0.799. In silico, the estimated sensitivity of our noninvasive Zygosity determination was 99.90% under 10% total cff-DNA concentration with 2 Gbp sequence data. As the cff-DNA concentration increased to 15%, the specificity was as high as 97% with 3.50 Gbp sequence data, much higher than 80% with 10% cff-DNA concentration. This study presents the feasibility to noninvasively determine Zygosity of twin pregnancy using target region sequencing, and illustrates the sensitivity and specificity under various detecting condition. Our method can act as an alternative approach for Zygosity determination of twin pregnancies in clinical practice.
