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At least 433 records · Page 24Linked to original sources
PubMed2004

Haplotype block and superblock structures of the alpha1-adrenergic receptor genes reveal echoes from the chromosomal past.

A significant proportion of the human genome is contained within haplotype blocks across which pairwise linkage disequilibrium (LD) is very high. However, LD is also often high between markers at more remote distances, and within different haplotype blocks. Here, we evaluate the origins of haplotype block structure in the three genes for alpha1 adrenergic receptors (alpha1-AR) in the human genome ( ADRA1A, ADRA1B and ADRA1D) by genotyping dense single-nucleotide polymorphism (SNP) marker maps, and show that LD signals between distant markers are due to the presence of extended haplotype superblocks in individuals with ancient chromosomes which have escaped historic recombination. ARs mediate the physiological effects of epinephrine and norepinephrine, and are targets of many therapeutic drugs. This work has identified haplotype backgrounds of alpha1-AR missense variants, haplotype block structures in US Caucasians and African Americans, and haplotype tag SNPs for each block, and we present strong evidence for ancient haplotype block superstructure at these genes which has been partially disrupted by recombination, and evidence for reinstatement of linkage disequilibrium by subsequent recombination events. ADRA1A is comprised of four haplotype blocks in US Caucasians, while in African Americans Block 1 is split. ADRA1B has four blocks in US Caucasians, but in African Americans only the first two blocks are present. ADRA1D has two blocks in US Caucasians, and the first block is replaced by two smaller blocks in African Americans. For both ADRA1A and ADRA1B, haplotype superstructures may represent a novel, higher-level hierarchy in the human genome, which may reduce redundancy of testing by further aggregation of genotype data.

Black or African American↗
PubMed2004

Pedigree generation for analysis of genetic linkage and association.

We have developed a software package, SIMLA (simulation of linkage and association), which can be used to generate pedigree data under user-specified conditions. The number and location of disease loci, disease penetrances, marker locations, and marker disequilibrium with a disease locus and with other markers can be controlled. In addition, the pedigree size and availability of genotype data may also be specified, and a number of rules for family ascertainment are available. Estimates for power and type I errors can be evaluated under a variety of conditions, as needed by the user. We developed this simulation program because there are no publicly available programs to simulate variable levels of both recombination and linkage disequilibrium (LD) in general pedigrees. Genetic researchers are routinely applying both tests of linkage and family-based tests of association in the search for complex disease genes, and a plethora of different statistical approaches are available. Thus there is a need for the flexible statistical simulation program that we describe. This is the only program that we are aware of that allows simulation of linkage and association for multiple markers in extended pedigrees, nuclear families or in sets of unrelated cases and controls. Furthermore, the program not only allows for variable levels of LD among markers but also between markers and disease loci. SIMLA can simulate the complex and variable levels of LD that have been observed at close markers across the genome and allows for realistic simulation of complex relationships between markers. The program will be useful for studying and comparing existing statistical tests, for developing new genetic linkage and association statistics, planning sample sizes for new studies, and interpreting genetic analysis results.

Algorithms↗
PubMed2005

Sibship T2 association tests of complex diseases for tightly linked markers.

For population case-control association studies, the false-positive rates can be high due to inappropriate controls, which can occur if there is population admixture or stratification. Moreover, it is not always clear how to choose appropriate controls. Alternatively, the parents or normal sibs can be used as controls of affected sibs. For late-onset complex diseases, parental data are not usually available. One way to study late-onset disorders is to perform sib-pair or sibship analyses. This paper proposes sibship-based Hotelling's T2 test statistics for high-resolution linkage disequilibrium mapping of complex diseases. For a sample of sibships, suppose that each sibship consists of at least one affected sib and at least one normal sib. Assume that genotype data of multiple tightly linked markers/haplotypes are available for each individual in the sample. Paired Hotelling's T2 test statistics are proposed for high-resolution association studies using normal sibs as controls for affected sibs, based on two coding methods: 'haplotype/allele coding' and 'genotype coding'. The paired Hotelling's T2 tests take into account not only the correlation among the markers, but also take the correlation within each sib-pair. The validity of the proposed method is justified by rigorous mathematical and statistical proofs under the large sample theory. The non-centrality parameter approximations of the test statistics are calculated for power and sample size calculations. By carrying out power and simulation studies, it was found that the non-centrality parameter approximations of the test statistics were accurate. By power and type I error analysis, the test statistics based on the 'haplotype/allele coding' method were found to be advantageous in comparison to the test statistics based on the 'genotype coding' method. The test statistics based on multiple markers can have higher power than those based on a single marker. The test statistics can be applied not only for bi-allelic markers, but also for multi-allelic markers. In addition, the test statistics can be applied to analyse the genetic data of multiple markers which contain double heterozygotes--that is, unknown linkage phase data. An SAS macro, Hotel_sibs.sas, is written to implement the method for data analysis.

Diabetes Mellitus↗
PubMed2002

Microarrays in pharmacogenomics--advances and future promise.

With their ability to provide global views of genome sequence and gene activity, microarrays have emerged as key analytical tools in the field of pharmacogenomics. Vast amounts of data must be collected and analyzed to meet pharmacogenomics' ambitious goals, ranging from identifying markers that predict individuals' responses to therapy to discovering new drug targets. Microarrays will be instrumental to these efforts because they provide bountiful sources of gene expression and genotypic data. Attesting to their productivity, microarrays have been the central technology used in thousands of peer-reviewed publications and have also become important contributors to many databases including PharmGKB, the Cancer Microarray Database and the database of single nucleotide polymorphisms (dbSNP). Microarrays are also making more focused contributions, however, in helping pursue hypothesis-driven inquiries that extend or complement broad genomic surveys. In addition, their potential as clinical tools is being increasingly recognized. This review identifies some of the varied and changing needs of pharmacogenomics research and discusses the ways in which microarrays are tending to these demands. The technique's strongpoints and limitations are examined, as well as its future potential.

Gene Expression↗
PubMed2001

Estimation of linkage disequilibrium for loci with multiple alleles: basic approach and an application using data from bighorn sheep.

The great expansion of population genetic data using molecular techniques now allows examination of the extent of linkage disequilibrium for many pairs of loci, each locus often with multiple alleles. The expectation-maximization (EM) algorithm for generating maximum likelihood estimates of gametic frequencies from multiallelic genotypic data is described and applied. The EM algorithm is used in desert bighorn sheep where the population size, and consequently the sample size, is often small. We calculated haplotype frequencies for all pairwise combinations of five major histocompatibility loci and three microsatellite loci in 14 populations; the performance of the algorithm is discussed. Disequilibrium values are calculated and tested for statistical significance. High levels of disequilibrium are found between all pairs of major histocompatibility complex (MHC) loci and between MHC and a linked microsatellite locus.

Alberta↗
PubMed2005

High-resolution identification of chromosomal abnormalities using oligonucleotide arrays containing 116,204 SNPs.

Mutation of the human genome ranges from single base-pair changes to whole-chromosome aneuploidy. Karyotyping, fluorescence in situ hybridization, and comparative genome hybridization are currently used to detect chromosome abnormalities of clinical significance. These methods, although powerful, suffer from limitations in speed, ease of use, and resolution, and they do not detect copy-neutral chromosomal aberrations--for example, uniparental disomy (UPD). We have developed a high-throughput approach for assessment of DNA copy-number changes, through use of high-density synthetic oligonucleotide arrays containing 116,204 single-nucleotide polymorphisms, spaced at an average distance of 23.6 kb across the genome. Using this approach, we analyzed samples that failed conventional karyotypic analysis, and we detected amplifications and deletions across a wide range of sizes (1.3-145.9 Mb), identified chromosomes containing anonymous chromatin, and used genotype data to determine the molecular origin of two cases of UPD. Furthermore, our data provided independent confirmation for a case that had been misinterpreted by karyotype analysis. The high resolution of our approach provides more-precise breakpoint mapping, which allows subtle phenotypic heterogeneity to be distinguished at a molecular level. The accurate genotype information provided on these arrays enables the identification of copy-neutral loss-of-heterozygosity events, and the minimal requirement of DNA (250 ng per array) allows rapid analysis of samples without the need for cell culture. This technology overcomes many limitations currently encountered in routine clinical diagnostic laboratories tasked with accurate and rapid diagnosis of chromosomal abnormalities.

Chromosome Aberrations↗
PubMed1995

Genotypic evolution of HIV-1 isolates from patients after a switch of therapy from zidovudine to didanosine.

The existence of zidovudine (ZDV)-resistant and didanosine (ddI)-resistant human immunodeficiency-1 (HIV-1) variants mutated in the reverse transcriptase (RT) gene has been previously demonstrated. In this study, we tried to follow up the genotypic changes in the RT after the switch of therapy from ZDV to ddI. We studied HIV-1 isolates from 11 patients undergoing ddI therapy. Genotypic data were obtained with differential polymerase chain reaction (PCR) and with direct sequencing after PCR. The prevalence of ZDV resistance-related mutations showed a very slow decrease, particularly when patients had been treated with ZDV for a long time. The appearance of a mutation at codon 74 seemed to be independent of the presence or absence of ZDV resistance-related mutations. The broad genotypic heterogeneity of the isolates and the complexity of the evolution in one patient's isolates plead for large sequencing studies of the RT genome in new therapeutic approaches.

Base Sequence↗
PubMed1993

Molecular and statistical approaches to the detection and correction of errors in genotype databases.

Errors in genotyping data have been shown to have a significant effect on the estimation of recombination fractions in high-resolution genetic maps. Previous estimates of errors in existing databases have been limited to the analysis of relatively few markers and have suggested rates in the range 0.5%-1.5%. The present study capitalizes on the fact that within the Centre d'Etude du Polymorphisme Humain (CEPH) collection of reference families, 21 individuals are members of more than one family, with separate DNA samples provided by CEPH for each appearance of these individuals. By comparing the genotypes of these individuals in each of the families in which they occur, an estimated error rate of 1.4% was calculated for all loci in the version 4.0 CEPH database. Removing those individuals who were clearly identified by CEPH as appearing in more than one family resulted in a 3.0% error rate for the remaining samples, suggesting that some error checking of the identified repeated individuals may occur prior to data submission. An error rate of 3.0% for version 4.0 data was also obtained for four chromosome 5 markers that were retyped through the entire CEPH collection. The effects of these errors on a multipoint map were significant, with a total sex-averaged length of 36.09 cM with the errors, and 19.47 cM with the errors corrected. Several statistical approaches to detect and allow for errors during linkage analysis are presented. One method, which identified families containing possible errors on the basis of the impact on the maximum lod score, showed particular promise, especially when combined with the limited retyping of the identified families. The impact of the demonstrated error rate in an established genotype database on high-resolution mapping is significant, raising the question of the overall value of incorporating such existing data into new genetic maps.

Bias↗
PubMed2001

Genetic analysis of case/control data using estimated haplotype frequencies: application to APOE locus variation and Alzheimer's disease.

There is growing debate over the utility of multiple locus association analyses in the identification of genomic regions harboring sequence variants that influence common complex traits such as hypertension and diabetes. Much of this debate concerns the manner in which one can use the genotypic information from individuals gathered in simple sampling frameworks, such as the case/control designs, to actually assess the association between alleles in a particular genomic region and a trait. In this paper we describe methods for testing associations between estimated haplotype frequencies derived from multilocus genotype data and disease endpoints assuming a simple case/control sampling design. These proposed methods overcome the lack of phase information usually associated with samples of unrelated individuals and provide a comprehensive way of assessing the relationship between sequence or multiple-site variation and traits and diseases within populations. We applied the proposed methods in a study of the relationship between polymorphisms within the APOE gene region and Alzheimer's disease. Cases and controls for this study were collected from the United States and France. Our results confirm the known association between the APOE locus and Alzheimer's disease, even when the epsilon 4 polymorphism is not contained in the tested haplotypes. This suggests that, in certain situations, haplotype information and linkage disequilibrium-induced associations between polymorphic loci that neighbor loci harboring functional sequence variants can be exploited to identify disease-predisposing alleles in large, freely mixing populations via estimated haplotype frequency methods.

Aged↗
PubMed1993

Characterization of human T-lymphotropic virus type I- and II-infected T-cell lines: antigenic, phenotypic, and genotypic analysis.

Eighteen long-term T-cell lines were established from peripheral blood mononuclear cells of individuals infected with human T-lymphotropic virus type I (HTLV-I) or II (HTLV-II). These cell lines (10 HTLV-I and 8 HTLV-II), representing diverse pathologic profiles and geographic regions, have been in culture for over 6 months and have constitutively produced p24gag antigen. Antigenic characterization of the cell lines by Western blot analysis demonstrated that all but one produced gag (p24) and env (gp46 or gp52) structural proteins; one HTLV-I-infected cell line exhibited an aberrant protein profile. Phenotypic analysis of the HTLV-infected cell lines demonstrated phenotypes consistent with activated T-cells (CD5+, CD25+, HLA-DR+). The HTLV-I-infected cell lines were predominantly CD4+ (IR, FS, A212, SP, 1657, 1742, 3669, 1996, and 3614), whereas EG was CD8+. The HTLV-II-infected cell lines were either CD4+ (H2A, Y17, G12.1), CD8+ (H1H, H2E, Y03, Y06), or both (H1B). Restriction map analysis and subtyping of the viral genomes demonstrated heterogeneity among these isolates. Of the HTLV-I-infected cell lines, six were subtype II, one was subtype III and, on the basis of additional restriction sites, another subtype, tentatively classified as subtype IV, could be identified for three of the HTLV-I-infected cell lines. Of the HTLV-II-infected cell lines, six were subtype HTLV-IIa and two were subtype HTLV-IIb. While the majority of the cell lines resemble the prototypic HTLV-I-infected (MT-2) and HTLV-II-infected (MoT) cell lines, the antigenic, phenotypic, and genotypic data collectively demonstrate heterogeneity among viral isolates representing diverse geographic regions.

Adult↗
PubMed2003

Familial idiopathic scoliosis: evidence of an X-linked susceptibility locus.

STUDY DESIGN: A genomic screen and statistical linkage analysis of a large sample of families with individuals having idiopathic scoliosis was performed. OBJECTIVES: To identify an X-linked susceptibility locus involved in the expression of familial idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: A large sample of families with individuals having idiopathic scoliosis (202 families; 1198 individuals) were diagnosed through physical examination and radiographic criteria, and genomic screening and genetic linkage analyses were performed. METHODS: Model-independent linkage analysis was used to screen genotyping data from 15 X-linked markers in 202 families (1198 individuals). Families were stratified based on the ratio of the likelihood of an X-linked dominant (XLD) inheritance model relative to that of an autosomal dominant (AD) model. Both model-independent and model-dependent linkage analyses were used to identify potential candidate regions. RESULTS: When the entire set of families were analyzed with model-independent methods, no result was significant at the 0.05 level for any of the markers. However, when the families were stratified based on the ratio of the likelihood of the X-linked dominant to autosomal dominant mode of inheritance, results from model-dependent linkage analysis of 15% of the families most likely to have X-linked dominant inheritance showed six adjacent markers with positive lod score values and a maximum lod score of 1.69 (theta = 0.2) at marker GATA172D05. A lod score of 2.23 at this same marker was found in a single family with six affected individuals. CONCLUSION: The results suggest that a region on the X chromosome may be linked to the expression of familial idiopathic scoliosis in a subset of these families.

Alleles↗
PubMed2006

SNP identification, linkage disequilibrium, and haplotype analysis for a 200-kb genomic region in a Korean population.

Understanding patterns of linkage disequilibrium (LD) across genomes may facilitate association mapping studies to localize genetic variants influencing complex diseases, a recognition that led to the International Haplotype Mapping Project (HapMap). Divergent patterns of haplotype frequency and LD across global populations require that the HapMap database be supplemented with haplotype and LD data from additional populations. We conducted a pilot study of the LD and haplotype structure of a genomic region in a Korean population. A total of 165 SNPs were identified in a 200-kb region of 22q13.2 by direct sequencing. Unphased genotype data were generated for 76 SNPs in 90 unrelated Korean individuals. LD, haplotype diversity, and recombination rates were assessed in this region and compared with the HapMap database. The pattern of LD and haplotype frequencies of Korean samples showed a high degree of similarity with Japanese data. There was a strong correlation between high LD and low recombination frequency in this region. We found considerable similarities in local LD patterns between three Asian populations (Han Chinese, Japanese, and Korean) and the CEPH population. Haplotype frequencies were, however, significantly different between them. Our results should further the understanding of distinctive Korean genomic features and assist in designing appropriate association studies.

Asian People↗
PubMed1994

Genetic haplotyping of ataxia-telangiectasia families localizes the major gene to an approximately 850 kb region on chromosome 11q23.1.

The genotyping data given localize the major A-T gene to an approximately 850 kb region. They also localize the group A A-T gene (ATA) to a region that contains the approximately 850 kb region. They are compatible with linking A-TFresno to 11q22-23. NBS-V2 does not link to this region. Four non-linking families contain only single affecteds, suggesting that these may be spontaneous mutations rather than evidence for an A-T gene outside the 11q22-23 region. Finally, two other non-linking families contain recombinant haplotypes that are compatible with a second A-T gene at 11q22-23, slightly distal to the approximately 850 kb region. However, convincing evidence for a second gene is still lacking.

Adult↗
PubMed1999

Familial dilated cardiomyopathy: echocardiographic diagnostic criteria for classification of family members as affected.

BACKGROUND: Echocardiographic criteria for left ventricular enlargement (LVE) used to classify subjects as affected in families with familial dilated cardiomyopathy (FDC) have been inconsistent. A recent report from a large Framingham echocardiographic study provides an opportunity to improve the assignment of LVE and FDC in kindreds, principally with a dilated phenotype. The objective of this study is to evaluate an alternative diagnostic criteria for FDC based only on LVE with no measure of fractional shortening (FS). METHODS AND RESULTS: We compared our proposed criteria for LVE and FDC with previous approaches by applying them to 166 adults derived from three large FDC pedigrees. Our proposed FDC diagnostic criteria are a sex- and height-specific method based only on LVE, without regard for FS, set as a 97.5% upper limit for left ventricular end-diastolic dimension (LVEDD) from the Framingham study. Other methods used to assign LVE were (1) a 95% upper limit for LVEDD by the Framingham study; (2) the method of Henry et al. (1980) based on age and body surface area (BSA); and (3) the National Heart, Lung, and Blood Institute (NHLBI) method with a cut point of LVEDD greater than 2.7 cm/BSA. Three other commonly used diagnostic criteria for FDC were based on various LVE standards combined with an FS of 27% to 30%. For LVE, the Framingham-97.5% was the most stringent (21 of 134 subjects identified; 15.7%), the NHLBI standard the least stringent (57 of 161 subjects identified; 35.4%), and the Henry-112% method intermediate (44 of 161 subjects identified; 27.3%). More women were identified with the Framingham method (57.1%) versus the Henry-112% (40.9%). The Henry-112% and NHLBI methods identified 11.4% and 7.0% of subjects with body mass indices (BMIs) of 35 or greater, respectively. For FDC, our proposed FDC diagnostic criteria identified similar numbers of subjects (21 subjects) as the three other criteria (range, 22 to 27 subjects), but inconsistency was noted (54.2% to 66.7%), with kappa values from 0.49 to 0.55 resulting from different sensitivities to sex, LVE, FS, and BMI. CONCLUSION: Our proposed FDC diagnostic criteria are stringent to assign FDC family members as affected compared with other commonly used criteria. The use of LVEDD alone may be preferable for FDC family screening, although further validation of this approach with phenotypic and genotypic data from other large FDC pedigrees is needed.

Adolescent↗
PubMed2003

Variance-component analysis of obesity in type 2 diabetes confirms loci on chromosomes 1q and 11q.

To study genetic loci influencing obesity in nuclear families with type 2 diabetes, we performed a genome-wide screen with 325 microsatellite markers that had an average spacing of 11 cM and a mean heterozygosity of approximately 75% covering all 22 autosomes. Genotype data were obtained from 562 individuals from 178 families from the Breda Study Cohort. These families were determined to have at least two members with type 2 diabetes. As a measure of obesity, the BMI of each diabetes patient was determined. The genotypes were analyzed using variance components (VCs) analysis implemented in GENEHUNTER 2 to determine quantitative trait loci influencing BMI. The VC analysis revealed two genomic regions showing VC logarithm of odds (LOD) scores > or =1.0 on chromosome 1 and chromosome 11. The regions of interest on both chromosomes were further investigated by fine-mapping with additional markers, resulting in a VC LOD score of 1.5 on chromosome 1q and a VC LOD of 2.4 on chromosome 11q. The locus on chromosome 1 has been implicated previously in diabetes. The locus on chromosome 11 has been implicated previously in diabetes and obesity. Our study to determine linkage for BMI confirms the presence of quantitative trait loci influencing obesity in subjects with type 2 diabetes on chromosomes 1q31-q42 and 11q14-q24.

Aged↗
PubMed1980

Phenotypic and genotypic characterization of some thermophilic species of Bacillus.

Some thermophilic species of Bacillus were characterized using biochemical tests, antibiotic sensitivity, bacteriocin and bacteriophage sensitivity, esterase patterns, DNA hybridization and % G+C content. The three caldo-active strains of bacilli isolated by Heinen (1971) were compared with strains of B. stearothermophilus. Eight of the strains examined showed characteristics which enabled them to be placed in the three main taxonomic groups suggested by Walker & Wolf (1971). Two strains showed characteristics of both groups 1 and 3. Examination of genotype data showed taxonomic groupings which differed from those based on phenotypic characterization.

Anti-Bacterial Agents↗
PubMed2004

Endolymphatic sac tumors in von Hippel-Lindau disease.

OBJECT: Von Hippel-Lindau (VHL) disease is a hereditary multiple-neoplasia syndrome mapping to chromosome 3p25-26. Endolymphatic sac (ELS) tumors have been identified as a neoplastic manifestation of VHL disease. The purpose of this study was to evaluate comprehensively the natural history of inner ear disease in a large population of patients with confirmed or suspected VHL disease and to correlate the clinical features with the VHL genotype. METHODS: The authors collated and analyzed clinical and genotypic data obtained in patients enrolled in an Institutional Review Board-approved protocol in which families and individuals affected by VHL disease were studied. These data included results from multidisciplinary history workups and physical examinations, imaging studies, and a battery of audiological tests. One hundred seventy-five patients were enrolled in the study, 129 with confirmed VHL disease and 46 of their family members in whom test results for VHL disease were negative and who served as controls. Twenty-one patients had ELS tumors that were evident on magnetic resonance images; three of them had bilateral ELS lesions. Hearing loss, often sudden in onset and severe to profound in nature, vestibulopathy, aural fullness, and tinnitus represented the primary symptoms of ELS tumor. Distinct patterns of auditory and vestibular dysfunction occurred at different stages of the disease. Phenotypic data showed that 17 of 21 patients with ELS tumors did not have pheochromocytomas, whereas all had VHL disease affecting the kidney, all but two had VHL disease affecting the central nervous system, and all but one had disease affecting the pancreas. Genotyping revealed 10 rearrangements (partial deletions), eight single bp substitutions, and one 3-bp insertion. Although there was no difference in the incidence of hearing loss between populations, symptoms of imbalance and aural fullness were more common in patients with VHL disease but without imaging evidence of ELS tumor than they were in family members who did not have VHL disease (p < 0.01). CONCLUSIONS: Endolymphatic sac tumors are frequently associated with VHL disease. Symptoms of disequilibrium or aural fullness in patients with VHL disease may be an early indication of endolymphatic dysfunction. Patients with VHL disease provide a unique opportunity to examine the effects of specific gene mutations and a discrete neoplastic process on the human inner ear. The study of ELS tumors in this group also provides a pathological model of ELS function and supplies evidence for a role of the ELS in clinical Ménière-like disease(s).

Adolescent↗
PubMed2002

Utilizing genomic DNA purified from clotted blood samples for single nucleotide polymorphism genotyping.

CONTEXT: Linking single nucleotide polymorphisms to disease etiology is expected to result in a substantial increase in the number of genetic tests available and performed at clinical laboratories. Whole blood serves as the most common DNA source for these tests. Because the number of blood samples rises with the number of genetic tests performed, alternative DNA sources will become important. One such alternative source is clotted blood, a by-product of serum extraction. Efficiently using an already procured blood sample would limit the overall number of samples processed by clinical laboratories. OBJECTIVE: To determine if DNA purified from clotted blood can be effectively used for single nucleotide polymorphism genotyping. DESIGN: DNA was purified from the clotted blood of 15 donors. Single nucleotide polymorphism genotyping for the methylenetetrahydrofolate reductase and factor V Leiden mutations was performed with each DNA sample by 2 independent methods. RESULTS: High-quality DNA was obtained from each of the 15 individual clotted blood samples as demonstrated by UV spectrophotometric analysis, gel electrophoresis, and polymerase chain reaction amplification. The DNA was used successfully to obtain genotype data from both the methylenetetrahydrofolate reductase and factor V single nucleotide polymorphism assays for all samples tested. CONCLUSIONS: Clotted blood is a clinically abundant sample type that can be used as a source of high-quality DNA for single nucleotide polymorphism genotyping.

DNA↗