Single Base Extension Assay Research Articles

Age estimation of burnt human remains through DNA methylation analysis.

The identification of human fire victims is a challenging task in forensic medicine. The heat-induced alterations of biological tissues can make the conventional anthropological analyses difficult. Even if the DNA profile of the victim is achieved, it is possible that no match can be found in a forensic DNA database, thus hindering positive identification. In such cases, any information useful to nail down a possible identity should be collected, such as DNA methylation analysis which could provide useful investigative leads. In the present study, five age-related epigenetic markers (ELOVL2, FHL2, KLF14, C1orf132, and TRIM59) were initially analysed in blood samples of 72 living Italian individuals of known age, using a Single Base Extension (SBE) assay. An age prediction model was built by multiple linear regression including all the markers (Mean Absolute Error, MAE: 3.15 years). This model was tested on 29 blood samples collected during autopsies from burnt human remains, already identified through DNA analysis, providing a MAE of 6.92 years. The model allowed a correct prediction in 79.3% of the cases (95% prediction interval), while six cases were associated with inaccurate predictions (min-max prediction error: 9.8-37.3 years). Among the different sample variables considered to explain these results, only the DNA degradation index was a relevant factor affecting the reliability of the predictions. In conclusion, the SBE typing of blood from burnt remains proved to be a reliable tool to estimate chronological age of most of the samples, also in consideration of its cost-effectiveness and the availability of CE sequencers in every forensic genetics laboratory.

New markers for flowering-time selection in sweet cherry

Sweet cherry (Prunus avium L.) is a fruit tree in the Rosaceae family grown worldwide for its tasty fruit. However, its yield may be threatened in warmer growing regions by insufficient dormancy, which usually occurs in late-blooming genotypes. Conversely, in cold regions, the yield is threatened by late spring frosts, especially for early flowering cultivars. It is therefore necessary to breed cultivars adapted to local weather conditions and avoid potential crop losses. New markers associated with the beginning of flowering were sought to enable molecular marker-assisted selection of genotypes tailored for different climatic conditions. Previously whole-genome sequenced 298 sweet cherry genotypes with nine years of phenotypic evaluation provided the basis for a genome-wide association study that allowed the identification of 163 single nucleotide polymorphisms and indels associated with flowering time, located on all sweet cherry chromosomes. This study confirmed the previously predicted polygenic basis of the trait. Three markers suitable for selection of late-blooming genotypes and one for early-blooming genotypes were selected and validated using independent 128 sweet cherry hybrids from different crossings. Individual markers for late beginning of flowering were able to select genotypes flowering at least three days after the reference (i.e. the earliest flowering) cultivar 'Kišiněvskaja'. Accumulation of preferred allele combinations for all three late-blooming markers has a synergistic effect, indicating delay of flowering 7.1 days after the reference cultivar on average. The marker for early beginning of flowering identified accessions flowering maximally five days after the earliest flowering reference cultivar 'Kišiněvskaja'. All four markers were integrated into a single base extension assay to help breeders with prediction of beginning of flowering for their breeding materials and cultivars.

Associations between interleukin-13, interleukin-4 and their receptor gene polymorphisms and susceptibility to atopic dermatitis in a Chinese Han population.

Background Atopic dermatitis (AD) is a common skin condition that occurs due to a combined effect of immune dysregulation, skin barrier dysfunction, changes in the cutaneous microbiome, and genetic factors. Recent data from both clinical trials and real-world studies indicate that dupilumab, a biological agent that inhibits interleukin 4 receptor-α is an effective drug in the treatment of AD, which further suggests the important role of IL-13 and IL-4 in the pathogenesis of AD. Objectives To assess the association between gene polymorphisms of IL-13, IL-13 receptor, IL-4, and IL-4 receptor and susceptibility to AD. Methods The single nucleotide polymorphisms (SNPs) of the above-mentioned genes were detected by single base extension (SNaPshot) assay. The association between these SNPs and AD risk was analysed using SPSS software. Results Two hundred and seventy-one subjects including 130 patients with AD and 141 healthy controls were enrolled. There were statistical differences between AD patients and controls in genotype distribution at rs2265753, rs6646259, and rs2254672 of the IL-13 receptor gene (P all < 0.001). Subjects with CG at rs2265753, AG at rs6646259 and TG at rs2254672 had increased risks for AD (P all < 0.001), and subjects with GG at rs2265753, rs6646259, and rs2254672 had reduced risks for AD (P all < 0.001). Limitation This was a single-centre and single-race study, with a relatively small sample size. Conclusions Findings from this study show that rs2265753, rs6646259 and rs2254672 of the IL-13 receptor gene are associated with susceptibility to AD.

Unraveling the paternal genetic structure and forensic traits of the Hui population in Liaoning Province, China using Y-chromosome analysis

The Hui people are the second-largest ethnic minority in China, and they are distributed throughout the country. A previous study explored the paternal genetic structure of the Hui population in nine different regions of China, but it overlooked the Liaoning province. In this study, we examined the paternal genetic makeup and forensic traits of the Hui population in Liaoning province by analyzing 157 Y-chromosome single nucleotide polymorphisms (Y-SNPs) and 26 short tandem repeats (Y-STRs). We successfully genotyped 282 unrelated male individuals from the Hui population of Liaoning province using the SNaPshot® single base extension assay and Goldeneye™ Y26 system kit (PEOPLESPOT R&D, Beijing, China). The results revealed high haplotypic diversity (0.9998) and identified 46 terminal haplogroups for the Hui population. Additional analyses, such as heat maps, principal component analysis (PCA), genetic distance (FST), Multidimensional scaling (MDS) analysis, and median-joining network (MJ) analysis, showed that the Hui population could be classified into three groups: Northwest Hui populations (NWH), including Liaoning, Xinjiang, Qinghai, Gansu, Ningxia, Shaanxi, and Henan; Hui populations from Sichuan and Shandong (SSH); and Yunnan Hui populations (YNH). Pairwise genetic distance (Rst) comparisons with other Chinese populations revealed that the Hui population displayed genetic affinity with the Han population. The comprehensive understanding of the Hui population in Liaoning province, explored by Y-SNPs and Y-STRs, can be utilized to interpret their genetic structure and enhance the accuracy of forensic databases.

MtDNA haplogroup A enhances the effect of obesity on the risk of knee OA in a Mexican population

To evaluate the influence of mitochondrial DNA haplogroups on the risk of knee OA in terms of their interaction with obesity, in a population from Mexico. Samples were obtained from (n = 353) knee OA patients (KL grade ≥ I) and (n = 364) healthy controls (KL grade = 0) from Mexico city and Torreon (Mexico). Both Caucasian and Amerindian mtDNA haplogroups were assigned by single base extension assay. A set of clinical and demographic variables, including obesity status, were considered to perform appropriate statistical approaches, including chi-square contingency tables, regression models and interaction analyses. To ensure the robustness of the predictive model, a statistical cross-validation strategy of B = 1000 iterations was used. All the analyses were performed using boot, GmAMisc and epiR package from R software v4.0.2 and SPSS software v24. The frequency distribution of the mtDNA haplogroups between OA patients and healthy controls for obese and non-obese groups showed the haplogroup A as significantly over-represented in knee OA patients within the obese group (OR 2.23; 95% CI 1.22–4.05; p-value = 0.008). The subsequent logistic regression analysis, including as covariate the interaction between obesity and mtDNA haplogroup A, supported the significant association of this interaction (OR 2.57; 95% CI 1.24–5.32; p-value = 0.011). The statistical cross-validation strategy confirmed the robustness of the regression model. The data presented here indicate a link between obesity in knee OA patients and mtDNA haplogroup A.

Qualitative Single Base Extension assay for Identification of Single Nucleotide Polymorphism in Mumps Virus Genome

Objective: Objective of the study was to standardize and evaluate suitability of Single Base Extension (SBE) singleplex assay for rapid routine monitoring of genetic homogeneity of virus samples, from productivity improvement experiments in Mumps vaccine. A Single Base Extension assay is a simple, cost effective tool for quick identification of single nucleotide polymorphism (SNP) at the three known sites in Mumps vaccine virus genome. The assay can be developed as a singleplex or multiplex version with potential for detection of up to ten SNP bases in a single reaction.Methods: SNaPshot kit from Applied Biosystems (ThermoFisher) was used to identify the nucleotide bases at the three SNP sites in Mumps virus genome. Approximate sizing locations of individual primers were determined using the SNaPshot Primer Focus Kit, also from Applied Biosystems. Genetic analyzer 3500 was used for the capillary electrophoresis of the processed samples. Results obtained from the data collection software were analyzed using GeneMapper software. Findings: Nucleotide G was identified at locations 1073 and 11345 and nucleotide C was identified at location 5261 for all tested mumps vaccine samples, thus demonstrating consistency in genetic homogeneity at the three known SNP hotspots in experimental mumps vaccine virus samples. Conclusion: The singleplex SBE assay was found to be a reliable and relatively inexpensive tool for routine monitoring of genetic homogeneity of vaccine virus samples, with potential for multiplexing that would reduce the cost and assay time even further.

Rapid and simple SNP genotyping for Bordetella pertussis epidemic strain MT27 based on a multiplexed single-base extension assay

Multilocus variable-number tandem repeat analysis (MLVA) is widely used for genotyping of Bordetella pertussis, the causative bacteria for pertussis. However, MLVA genotyping is losing its discriminate power because prevalence of the epidemic MT27 strain (MLVA-27) is increasing worldwide. To address this, we developed a single nucleotide polymorphism (SNP) genotyping method for MT27 based on multiplexed single-base extension (SBE) assay. A total of 237 MT27 isolates collected in Japan during 1999–2018 were genotyped and classified into ten SNP genotypes (SG1 to SG10) with a Simpson’s diversity index (DI) of 0.79 (95% CI 0.76–0.82). Temporal trends showed a marked increase in the genotypic diversity in the 2010s: Simpson’s DI was zero in 1999–2004, 0.16 in 2005–2009, 0.83 in 2010–2014, and 0.76 in 2015–2018. This indicates that the SNP genotyping is applicable to the recently circulating MT27 strain. Additionally, almost all outbreak-associated MT27 isolates were classified into the same SNP genotypes for each outbreak. Multiplexed SBE assay allows for rapid and simple genotyping, indicating that the SNP genotyping can potentially be a useful tool for subtyping the B. pertussis MT27 strain in routine surveillance and outbreak investigations.

Genetic substructure and forensic characteristics of Chinese Hui populations using 157 Y-SNPs and 27 Y-STRs

The Hui group is the second largest ethnic minority and one of the most widespread ethnic groups in China. However, the genetic architecture of the Hui population remains largely unexplored, particularly with respect to the male-specific region of the Y chromosome. Here, we studied nine Hui populations (Xinjiang, Qinghai, Gansu, Ningxia, Shaanxi, Henan, Shandong, Sichuan, Yunnan) using 157 Y-chromosome single nucleotide polymorphisms (Y-SNPs) and 27 short tandem repeats (Y-STRs) to unravel their genetic substructure and forensic characteristics. A total of 650 unrelated male samples from the Hui populations were genotyped by SNaPshot®, a single base extension (SBE) assay. Finally, 95 terminal haplogroups and high haplotype diversity (0.9999) were observed in Hui populations. Frequency heat map matrices, genetic distance (FST) and network analysis within Hui populations indicated that these nine Hui populations can be divided into three groups: Hui populations from the northwest (NWH), Hui populations from Sichuan and Shandong (SSH), and Hui populations from Yunnan (YNH). Our results suggested that we should use different databases for different Hui samples in forensic cases. Comparison with other populations that used different population genetic analysis revealed that the Hui populations had close relationships with East Asian populations, especially Chinese Han population. Overall, the high-resolution panel with Y-SNPs and Y-STRs gives new and complete insight into Hui populations, which can be used to interpret the genetic substructure of Hui populations and affect the utility of forensic databases.

Outside Back Cover: Separation‐free single‐base extension assay with fluorescence resonance energy transfer for rapid and convenient determination of DNA methylation status at specific cytosine and guanine dinucleotide sites

DOI: 10.1002/elps.201800144 The cover picture shows a separation-free single base extension (SBE) assay based on fluorescence resonance energy transfer (FRET) for rapid detection of 5-methylcytosine (mC). A single base-extended primer forms, which is 5'-Cy3- and 3'-Cy5-tagged. A Cy5-labeled terminator is incorporated into the 3'-end of the extension primer if the added terminator is complementary to the target nucleotide. The Cy3 donor and Cy5 acceptor are in close proximity in the SBE product. Illumination of the donor results in FRET and excitation of the Cy5 acceptor, generating fluorescence from the acceptor.

Separation-free single-base extension assay with fluorescence resonance energy transfer for rapid and convenient determination of DNA methylation status at specific cytosine and guanine dinucleotide sites.

A separation-free single-base extension (SBE) assay utilizing fluorescence resonance energy transfer (FRET) was developed for rapid and convenient interrogation of DNA methylation status at specific cytosine and guanine dinucleotide sites. In this assay, the SBE was performed in a tube using an allele-specific oligonucleotide primer (i.e., extension primer) labeled with Cy3 as a FRET donor fluorophore at the 5'-end, a nucleotide terminator (dideoxynucleotide triphosphate) labeled with Cy5 as a FRET acceptor, a PCR amplicon derived from bisulfite-converted genomic DNA, and a DNA polymerase. A single base-extended primer (i.e., SBE product) that was 5'-Cy3- and 3'-Cy5-tagged was formed by incorporation of the Cy5-labeled terminator into the 3'-end of the extension primer, but only if the terminator added was complementary to the target nucleotide. The resulting SBE product brought the Cy3 donor and the Cy5 acceptor into close proximity. Illumination of the Cy3 donor resulted in successful FRET and excitation of the Cy5 acceptor, generating fluorescence emission from the acceptor. The capacity of the developed assay to discriminate as low as 10% methylation from a mixture of methylated and unmethylated DNA was demonstrated at multiple cytosine and guanine dinucleotide sites.

Mitochondrial DNA haplogroups associated with MRI-detected structural damage in early knee osteoarthritis

Magnetic resonance imaging (MRI)-detected structural features are associated with increased risk of radiographic osteoarthritis (ROA). Specific mitochondrial DNA (mtDNA) haplogroups have been associated with incident ROA. Our objective was to compare the presence of MRI-detected structural features across mtDNA haplogroups among knees that developed incident ROA. Knees from the Osteoarthritis Initiative (OAI) that developed incident ROA during 48 months follow-up were identified from Caucasian participants. mtDNA haplogroups were assigned based on a single base extension assay. MRIs were obtained annually between baseline and 4-year follow-up and scored using the MRI Osteoarthritis Knee Score (MOAKS). The association between mtDNA haplogroups and MRI-detected structural features was estimated using log-binomial regression. Participants who carried haplogroup H served as the reference group. The sample included 255 participants contributing 277 knees that developed ROA. Haplogroups included H (116, 45%), J (17, 7%), T (26, 10%), Uk (61, 24%), and the remaining less common haplogroups ("others") (35, 14%). Knees of participants with haplogroup J had significantly lower risk of medium/large bone marrow lesions (BMLs) in the medial compartment [3.2%, relative risks (RR)=0.17; 95%CI: 0.05, 0.64; P=0.009] compared to knees of participants who carried haplogroup H [16.3%], as did knees from participants within the "others" group [2.8%, RR=0.20; 95%CI: 0.08, 0.55; P=0.002], over the 4year follow-up period. mtDNA haplogroup J was associated with lower risk of BMLs in the medial compartment among knees that developed ROA. Our results offer a potential hypothesis to explain the mechanism underlying the previously reported protective association between haplogroup J and ROA.

Diagnostic value of histone 3 mutations in osteoclast-rich bone tumors

Differentiating osteoclast-rich lesions of bone (giant cell tumor of bone [GCTB], chondroblastoma [CBA], and aneurysmal bone cyst [ABC]) can be challenging, especially in small biopsies or fine-needle aspirations. Mutations affecting codons 34 and 36 of either H3 Histone Family Member 3A (H3F3A) and/or 3B (H3F3B) are characteristically seen in GCTB and CBAs. We devised a simple assay to identify these mutations and evaluated its applicability for routine clinical diagnosis. One hundred twenty-four tissue specimens from 108 patients (43 GCTBs, 38 CBAs and 27 ABCs) were collected from the archives of the Calgary Laboratory Services/University of Calgary and Vanderbilt University Medical Center. Histology was reviewed by an expert orthopedic pathologist. A single base extension assay (SNaPshot) is used to interrogate each nucleotide in codons 34 and 36 of H3F3A and codon 36 of H3F3B. Final diagnoses were generated after re-reviewing cases and incorporating molecular findings. Of 43 GCTBs, 38 (88%) had an H3F3A G34W mutation; 35 of 38 CBAs (92%) had a K36M mutation in either H3F3B (N = 31; 82%) or H3F3A (N = 4; 11%); none of 27 ABCs had a tested mutation. Molecular findings changed the histomorphologic diagnosis in 5 cases (3 GCTB changed to ABC, and 2 ABC changed to GCTB). These findings support the diagnostic utility of mutational analysis for this differential diagnosis in certain challenging cases when clinicoradiologic and histomorphologic features are not definitive, particularly for distinguishing cellular ABC versus GCTB with secondary ABC.

HRM and SNaPshot as alternative forensic SNP genotyping methods

Single nucleotide polymorphisms (SNPs) have been widely used in forensics for prediction of identity, biogeographical ancestry (BGA) and externally visible characteristics (EVCs). Single base extension (SBE) assays, most notably SNaPshot® (Thermo Fisher Scientific), are commonly used for forensic SNP genotyping as they can be employed on standard instrumentation in forensic laboratories (e.g. capillary electrophoresis). High resolution melt (HRM) analysis is an alternative method and is a simple, fast, single tube assay for low throughput SNP typing. This study compares HRM and SNaPshot®. HRM produced reproducible and concordant genotypes at 500 pg, however, difficulties were encountered when genotyping SNPs with high GC content in flanking regions and differentiating variants of symmetrical SNPs. SNaPshot® was reproducible at 100 pg and is less dependent on SNP choice. HRM has a shorter processing time in comparison to SNaPshot®, avoids post PCR contamination risk and has potential as a screening tool for many forensic applications.

Analysis of four PCR/SNaPshot multiplex assays analyzing 52 SNPforID markers

The SNPforID consortium identified a panel of 52 SNPs for forensic analysis that has been used by several laboratories worldwide. The original analysis of the 52 SNPs was based on a single multiplex reaction followed by two single-base-extension (SBE) reactions each of which was analyzed using capillary electrophoresis. The SBE assays were designed for high throughput genetic analyzers and were difficult to use on the single capillary ABI PRISM 310 Genetic Analyzer and the latest generation 3500 Genetic Analyzer, as sensitivity on the 310 was low and separation of products on the 3500 with POP-7™ was poor. We have modified the original assay and split it into four multiplex reactions, each followed by an SBE assay. These multiplex assays were analyzed using polymer POP-4™ on ABI 310 PRISM® and polymers POP-4™, POP-6™ and POP-7™ on the 3500 Genetic Analyzer. The assays were sensitive and reproducible with input DNA as low as 60 pg using both the ABI 310 and 3500. In addition, we found that POP-6™ was most effective with the 3500, based on the parameters that we assessed, achieving better separation of the small SBE products; this conflicted with the recommended use of POP-7™ by the instrument manufacturer. To support the use of the SNP panel in casework in Malaysia we have created an allele frequency database from 325 individuals, representing the major population groups within Malaysia. Population and forensic parameters were estimated for all populations and its efficacy evaluated using 51 forensic samples from challenging casework.

Forensically relevant SNaPshot® assays for human DNA SNP analysis: a review.

Short tandem repeats are the gold standard for human identification but are not informative for forensic DNA phenotyping (FDP). Single-nucleotide polymorphisms (SNPs) as genetic markers can be applied to both identification and FDP. The concept of DNA intelligence emerged with the potential for SNPs to infer biogeographical ancestry (BGA) and externally visible characteristics (EVCs), which together enable the FDP process. For more than a decade, the SNaPshot® technique has been utilised to analyse identity and FDP-associated SNPs in forensic DNA analysis. SNaPshot is a single-base extension (SBE) assay with capillary electrophoresis as its detection system. This multiplexing technique offers the advantage of easy integration into operational forensic laboratories without the requirement for any additional equipment. Further, the SNP panels from SNaPshot® assays can be incorporated into customised panels for massively parallel sequencing (MPS). Many SNaPshot® assays are available for identity, BGA and EVC profiling with examples including the well-known SNPforID 52-plex identity assay, the SNPforID 34-plex BGA assay and the HIrisPlex EVC assay. This review lists the major forensically relevant SNaPshot® assays for human DNA SNP analysis and can be used as a guide for selecting the appropriate assay for specific identity and FDP applications.

Association of CD40 gene polymorphisms and serum CD40 levels with the pathogenesis of systemic lupus erythematosus.

Objective To explore the association of CD40 gene single nucleotide polymorphisms (SNPs) and haplotypes with the susceptibility to systemic lupus erythematosus (SLE), as well as the association of serum levels and genotypes of CD40 with the occurrence of SLE. Methods A multiplex PCR single-base extension assay (PCR-SBE) and DNA sequencing were performed to analyze 4 SNPs of the CD40 gene, including rs1883832 C/T, rs13040307 C/T, rs752118 C/T and rs3765459 G/A, in 205 patients with SLE (SLE group) and 220 healthy human controls (control group). Enzyme-linked immunosorbent assay (ELISA) was conducted to measure serum levels of CD40 in these subjects. Results Compared with the control group, the SLE group showed significantly increased serum levels of CD40(P < 0.05). There were significant differences in genotype and allele frequencies of the SNP rs1883832 C/T in the CD40 gene between the SLE group and control group (all P < 0.01). Relative risk analysis showed that the risk of developing SLE in rs1883832 T allele carriers was 1.517 times that in rs1883832 C allele carriers (OR = 1.517, 95% CI: 1.157-1.990, P = 0.003). Moreover, serum levels of CD40 were significantly higher in rs1883832 T allele carriers than in rs1883832 C allele carriers (P < 0.01). The risk of developing SLE was significantly increased in TCCA haplotype carriers compared with the healthy controls (OR = 2.322, 95% CI: 1.181 -4.564, P = 0.012). Conclusion The CD40 gene rs1883832 C/T polymorphism and its TCCA haplotype were both associated with the occurrence of SLE, and the rs1883832 T allele may be a gene predisposing to SLE. Key words: Lupus erythematosus, systemic; Antigens, CD40; Polymorphism, single nucleotide; Haplotypes; Genotype; Alleles

A Microbead-based Single Base Extension Assay for the Detection of Known Single-base Changes in Genomic DNA

Abstract Biotinylated single base extension (SBE) products that can fluoresce through the successful incorporation of fluorophore-labeled dideoxynucleoside triphosphate were immobilized on streptavidin-coated magnetic bead surfaces via the biotin–streptavidin interaction. The resultant beads were washed and packed into a capillary, followed by fluorescence imaging for detection. Using the above strategy, our bead-based SBE assay could clearly identify the allelic compositions at the targeted site on a tested DNA sequence.

HapB3 and the deep intronic variant c.1129-5923 C&gt;G of the dihydropyrimidine dehydrogenase gene (DPYD) to predict toxicity in stage III colon cancer (CC) patients (pts) (NCCTG Alliance N0147).

508 Background: Severe adverse events (AEs) to 5-fluorouracil (5-FU) constitute a major dilemma in CC treatment. We recently demonstrated that specific deleterious DPYD variants in the coding region were highly predictive of grade &gt;3 (G3+) AEs in stage III CC pts receiving adjuvant 5-FU based combination chemotherapy [Lee et al. JNCI. In press]. Other studies have suggested potential associations between AEs and non-coding DPYD variants: a novel haplotype (HapB3) containing three intronic variants (c.483+18 G&gt;A, c.680+139 G&gt;A, and c.959-51 T&gt;C), one synonymous variant (c.1236 G&gt;A, E412E), and a deep intronic variant (c.1129-5923 C&gt;G) that affects pre-mRNA splicing. However, these studies included a diversity of cancer types, stages and treatments. The findings require further evaluation in a refined population. Methods: A total of 2,134 Caucasian stage III CC pts without DPYD*2A, D949V, and I560S variants from NCCTG N0147 trial who received adjuvant FOLFOX or FOLFIRI +/- cetuximab were genotyped by multiplexed single-base extension assays on the Sequenom MassARRAY. G3+ AEs were recorded (CTCAE v3) and classified as common to 5-FU treatment (5FU-AEs). Logistic regressions were used to assess the univariate and multivariate associations. Results: Analyzed pts displayed the following characteristics: 54.3% male, median age 59 [19-85], proficient MMR 87.5%, PS-0 76.5%, + irinotecan 8.5%, and + cetuximab 46.5%. Pts carrying c.1129-5923 C&gt;G were significantly associated with higher risk of G3+ 5FU-AEs (Odds Ratio [OR]=1.539, 95% confidence interval [CI]=1.001 – 2.367, p=0.049). Only marginal association was observed for one of the HapB3 variants, c.1236 G&gt;A (p=0.058). A linearly increasing risk of G3+ 5FU-AEs was identified for HapB3, comparing pts with no, one or &gt;1 variant present (unadjusted OR=1.539, 95% CI=1.001 – 2.367, p=0.041; adjusted OR=1.198, 95% CI=0.998-1.437, p=0.052). Conclusions: In the largest study to date, c.1129-5923 C&gt;G and HapB3 were predictive of 5FU-AE risk in stage III CC patients without DPYD*2A, D949V, and I560S variants receiving 5-FU-based combination chemotherapy.

The Glass Slide Extraction System Snap Card Improves Non-Invasive Prenatal Genotyping in Pregnancies with Antibodies

Background: Determination of fetal blood groups in maternal plasma samples critically depends on adequate pre-analytical steps for optimal amplification of fetal DNA. We compared the extraction of cell-free DNA by binding on a glass surface (BCSI SNAP™ Card) with an automated system based on bead technology (MagnaPure compact™). Methods: Maternal blood samples from 281 pregnancies (7th-39th week of gestation) with known antibodies were evaluated in this study. Both the SNAP card and the MagnaPure method were applied to isolate DNA in order to directly compare the amplification in a single base extension assay and/or real-time PCR. Results: The mean concentration of total DNA obtained by the SNAP card (33.8 ng/µl) exceeded more than twofold that of MagnaPure extraction (15.7 ng/µl). SNAP card-extracted samples allowed to detect 3.7 single nucleotide polymorphisms (SNPs) versus 2.5 SNPs in MagnaPure extracts to control for traces of fetal DNA. This difference is highest for samples from 7th-13th week of gestation. Conclusion: The SNAP card system improves DNA extraction efficacy for prenatal diagnosis in maternal blood samples and provides an at least eightfold higher total amount of DNA for the ensuing analysis. Its advantage is most evident for samples from early stages of pregnancy and thus especially valuable for pregnancies with antibodies.

SNaPshot assay for the detection of the most common CFTR mutations in infertile men.

Congenital bilateral absence of vas deferens (CBAVD) is the most common CFTR-related disorder (CFTR-RD) that explains about 1–2% of the male infertility cases. Controversial data have been published regarding the involvement of CFTR mutations in infertile men with non-obstructive azoospermia and oligozoospermia. Here, we describe single base extension (SNaPshot) assay for detection of 11 common CFTR mutations: F508del, G542X, N1303K, 621+1G->T, G551D, R553X, R1162X, W1282X, R117H, 2184insA and 1717-1G->A and IVS8polyT variants. The assay was validated on 50 previously genotyped samples and was used to screen a total of 369 infertile men with different impairment of spermatogenesis and 136 fertile controls. Our results show that double heterozygosity of cystic fibrosis (CF) and CFTR-related disorder (CFTR-RD) mutations are found in a high percentage (22.7%) of infertile men with obstructive azoospermia, but not in other studied groups of infertile men. The SNaPshot assay described here is an inexpensive, fast and robust method for primary screening of the most common CFTR mutations both in patients with classical CF and CFTR-RD. It can contribute to better understanding of the role of CFTR mutations in impaired spermatogenesis, ultimately leading to improved management of infertile men.