Accuracy of genotyping using the TaqMan PCR assay for single nucleotide polymorphisms responsible for thiopurine sensitivity in Japanese patients with inflammatory bowel disease

Applications of Environmental DNA (eDNA) in Monitoring the Endangered Status and Evaluating the Stock Enhancement Effect of Tropical Sea Cucumber Holothuria Scabra

The tropical sea cucumber Holothuria scabra is naturally found in the Indo-West Pacific. However, due to their commercial value, natural H. scabra populations have declined significantly in recent years, resulting in its status as an endangered species. Surveys of H. scabra resource pose a challenge due to its specific characteristics, such as sand-burrowing behavior. To overcome this problem, our study established a convenient and feasible method for assessing H. scabra resources using environmental DNA (eDNA) monitoring technology. First, H. scabra-specific TaqMan primers and probe were designed based on its cox1 gene, followed by the development of an eDNA monitoring method for H. scabra in two separate sea areas (Xuwen and Daya Bay). The method was subsequently employed to investigate the distribution of H. scabra and assess the effects of aquaculture stock enhancement through juvenile releasing in the Weizhou Island sea area. The H. scabra eDNA monitoring approach was found to be more appropriate and credible than traditional methods, and a positive impact of stocking on H. scabra populations was observed. In summary, this is the first report to quantify eDNA concentration in a Holothuroidea species, and it provides a convenient and accurate method for surveying H. scabra resources. This study introduces novel concepts for eDNA-based detection of endangered marine benthic animals and monitoring their population distribution and abundance.

Comparison of Direct Sequencing with Real-time PCR High Resolution Melt and PCR Restriction Fragment Length Polymorphism Analysis to Identify Clinically Important Candida Species

Background: Candida albicans is the predominant yeast reported from human infection. Non-albicans Candida species have been recently developed as medically vital fungi. Therefore, it is essential to detect and identify the pathogens at the species level to prescribe appropriate treatment. Methods: This study assessed two complementary methods, including real-time polymerase chain reaction-high resolution melt (PCR-HRM) and polymerase chain reaction-restriction fragment length morphism (PCR-RFLP) with standard PCR and Sanger sequencing as the benchmark. Results: In total, 66 samples were tested, and two newly-advanced assays were more effective and displayed comprehensive concordance (66/66, 100%) with Sanger sequencing outcomes. Moreover, accurate and economical tests were positively advanced by real-time PCR-HRM for C. albicans and C. parapsilosis complexes. Conclusions: Given the number of studies performed on the comparison of sensitivity and specificity of phenotypic and genotypic methods to diagnose and identify invasive fungal pathogens and the findings of this study, it could be stated that the correlative PCR-HRM and PCR-RFLP methods were effectively advanced as substitutes for conventional Sanger sequencing for the reasonable identification. However, supplementary evaluations and confirming studies should be carried out with a broad range of samples to standardize this method for routine application in medical laboratories.

The correlation of salivary telomere length and single nucleotide polymorphisms of the ADIPOQ, SIRT1 and FOXO3A genes with lifestyle-related diseases in a Japanese population

Background

It has been reported that genetic factors are associated with risk factors and onset of lifestyle-related diseases, but this finding is still the subject of much debate.

Objective

The aim of the present study was to investigate the correlation of genetic factors, including salivary telomere length and three single nucleotide polymorphisms (SNPs) that may influence lifestyle-related diseases, with lifestyle-related diseases themselves.

Methods

In one year at a single facility, relative telomere length and SNPs were determined by using monochrome multiplex quantitative polymerase chain reaction and TaqMan SNP Genotyping Assays, respectively, and were compared with lifestyle-related diseases in 120 Japanese individuals near our university.

Results

In men and all participants, age was inversely correlated with relative telomere length with respective p values of 0.049 and 0.034. In men, the frequency of hypertension was significantly higher in the short relative telomere length group than in the long group with unadjusted p value of 0.039, and the difference in the frequency of hypertension between the two groups was of borderline statistical significance after adjustment for age (p = 0.057). Furthermore, in men and all participants, the sum of the number of affected lifestyle-related diseases, including hypertension, was significantly higher in the short relative telomere length group than in the long group, with p values of 0.004 and 0.029, respectively. For ADIPOQ rs1501299, men’s ankle brachial index was higher in the T/T genotype than in the G/G and G/T genotypes, with p values of 0.001 and 0.000, respectively. For SIRT1 rs7895833, men’s body mass index and waist circumference and all participants’ brachial-ankle pulse wave velocity were higher in the A/G genotype than in the G/G genotype, with respective p values of 0.048, 0.032 and 0.035. For FOXO3A rs2802292, women’s body temperature and all participants’ saturation of peripheral oxygen were lower in the G/T genotype than in the T/T genotype, with respective p values of 0.039 and 0.032. However, relative telomere length was not associated with physiological or anthropometric measurements except for height in men (p = 0.016). ADIPOQ rs1501299 in men, but not the other two SNPs, was significantly associated with the sum of the number of affected lifestyle-related diseases (p = 0.013), by genotype. For each SNPs, there was no significant difference in the frequency of hypertension or relative telomere length by genotype.

Conclusion

Relative telomere length and the three types of SNPs determined using saliva have been shown to be differentially associated with onset of and measured risk factors for lifestyle-related diseases consisting mainly of cardiovascular diseases and cancer.

Comparison of Direct Sequencing, Real-Time PCR-High Resolution Melt (PCR-HRM) and PCR-Restriction Fragment Length Polymorphism (PCR-RFLP) Analysis for Genotyping of Common Thiopurine Intolerant Variant Alleles NUDT15 c.415C>T and TPMT c.719A>G (TPMT*3C)

Thiopurine intolerance and treatment-related toxicity, such as fatal myelosuppression, is related to non-function genetic variants encoding thiopurine S-methyltransferase (TPMT) and Nudix hydrolase 15 (NUDT15). Genetic testing of the common variants NUDT15:NM_018283.2:c.415C>T (Arg139Cys, dbSNP rs116855232 T allele) and TPMT: NM_000367.4:c.719A>G (TPMT*3C, dbSNP rs1142345 G allele) in East Asians including Chinese can potentially prevent treatment-related complications. Two complementary genotyping approaches, real-time PCR-high resolution melt (PCR-HRM) and PCR-restriction fragment length morphism (PCR-RFLP) analysis were evaluated using conventional PCR and Sanger sequencing genotyping as the gold standard. Sixty patient samples were tested, revealing seven patients (11.7%) heterozygous for NUDT15 c.415C>T, one patient homozygous for the variant and one patient heterozygous for the TPMT*3C non-function allele. No patient was found to harbor both variants. In total, nine out of 60 (15%) patients tested had genotypic evidence of thiopurine intolerance, which may require dosage adjustment or alternative medication should they be started on azathioprine, mercaptopurine or thioguanine. The two newly developed assays were more efficient and showed complete concordance (60/60, 100%) compared to the Sanger sequencing results. Accurate and cost-effective genotyping assays by real-time PCR-HRM and PCR-RFLP for NUDT15 c.415C>T and TPMT*3C were successfully developed. Further studies may establish their roles in genotype-informed clinical decision-making in the prevention of morbidity and mortality due to thiopurine intolerance.

Time to wake up: No impact of COMT Val158Met gene variation on circadian preferences, arousal regulation and sleep

Dopamine has been implicated in the regulation of sleep-wake states and the circadian rhythm. However, there is no consensus on the impact of two established dopaminergic gene variants: the catechol-O-methyltransferase Val158Met (COMT Val158Met; rs4680) and the dopamine D4 receptor Exon III variable-number-of-tandem-repeat polymorphism (DRD4 VNTR). Pursuing a multi-method approach, we examined their potential effects on circadian preferences, arousal regulation and sleep. Subjects underwent a 7-day actigraphy assessment (SenseWear Pro3), a 20-minute resting EEG (analyzed using VIGALL 2.0) and a body mass index (BMI) assessment. Further, they completed the Morningness-Eveningness Questionnaire (MEQ), the Epworth Sleepiness Scale (ESS) and the Pittsburgh Sleep Quality Index (PSQI). The sample comprised 4625 subjects (19-82 years) genotyped for COMT Val158Met, and 689 elderly subjects (64-82 years) genotyped for DRD4 VNTR. The number of subjects varied across phenotypes. Power calculations revealed a minimum required phenotypic variance explained by genotype ranging between 0.5% and 1.5% for COMT Val158Met and between 3.3% and 6.0% for DRD4 VNTR. Analyses did not reveal significant genotype effects on MEQ, ESS, PSQI, BMI, actigraphy and EEG variables. Additionally, we found no compelling evidence in sex- and age-stratified subsamples. Few associations surpassed the threshold of nominal significance (p < .05), providing some indication for a link between DRD4 VNTR and daytime sleepiness. Taken together, in light of the statistical power obtained in the present study, our data particularly suggest no impact of the COMT Val158Met polymorphism on circadian preferences, arousal regulation and sleep. The suggestive link between DRD4 VNTR and daytime sleepiness, on the other hand, might be worth investigation in a sample enriched with younger adults.

Thiopurine S-methyltransferase testing for averting drug toxicity in patients receiving thiopurines: a systematic review

AIM

Thiopurine S-methyltransferase (TPMT) testing is used in patients receiving thiopurines to identify enzyme deficiencies and risk for adverse drug reactions. It is uncertain whether genotyping is superior to phenotyping. The objectives were to conduct a systematic review of TPMT-test performance studies.

MATERIALS & METHODS

Electronic and grey literature sources were searched for studies reporting test performance compared with a reference standard. Sixty-six eligible studies were appraised for quality.

RESULTS

Thirty phenotype-genotype and six phenotype-phenotype comparisons were of high quality. The calculated sensitivity and specificity for genotyping to identify a homozygous mutation ranged from 0.0-100.0% and from 97.8-100.0%, respectively.

CONCLUSION

Clinical decision-makers require high-quality evidence of clinical validity and clinical utility of TPMT genotyping to ensure appropriate use in patients.

Accuracy of polymerase chain reaction-restriction fragment length polymorphism for RET rs2435357 genotyping as Hirschsprung risk

BACKGROUND

Recently, the common RET rs2435357 variant has been shown to be strongly related to Hirschsprung disease (HSCR) in the Indonesian population. This association study was conducted in developed areas using high-throughput TaqMan polymerase chain reaction (PCR) assay. Although the TaqMan method is less time-consuming, it requires a special more expensive PCR machine and a highly skilled analyst. In this study, we analyzed the usefulness of the PCR-restriction fragment length polymorphism (RFLP) method for genotyping RET rs2435357 polymorphism in Indonesian HSCR patients given the limitation of resource allocation for more expensive technologies.

MATERIALS AND METHODS

We compared our previous genotyping results of RET rs2435357 in 53 HSCR patients and 86 controls using the TaqMan PCR assay with the PCR-RFLP technique. Furthermore, we included an additional 40 HSCR patients and 50 controls and subsequently genotyped all subjects using the PCR-RFLP method.

RESULTS

Compared with our previous genotyping data of RET rs2435357 using the TaqMan PCR assay, the PCR-RFLP method indicated 100% concordant results. The overall accuracy of the PCR-RFLP for RET rs2435357 genotyping was 100%. In addition, case-control analysis demonstrated that RET rs2435357 is significantly correlated with HSCR (P = 2.2 × 10(-13)) with an odds ratio of 5.1 (95% confidence interval = 3.2-8.1). The transmission disequilibrium test revealed that risk allele (T) at rs2435357 is significantly overtransmitted to probands at a transmission rate (τ) of 0.87 (P = 1.5 × 10(-6)).

CONCLUSIONS

The PCR-RFLP method is reliable and affordable for genotyping of RET rs2435357 polymorphism in developing countries. Our results strengthen the proof that the RET rs2435357 variant is a genetic risk for HSCR in Indonesia.

Influence of SLCO1B1 polymorphism on maintenance therapy for childhood leukemia

BACKGROUND

Management of the adverse effects of chemotherapy is essential to improve outcome of children with leukemia. Some genetic polymorphisms can predict treatment-related toxicity, and be used individually in dose modification of 6-mercaptopurine (6-MP) and methotrexate (MTX) in maintenance therapy for childhood acute lymphoblastic leukemia (ALL). We investigated associations between clinical course and candidate gene polymorphisms less evaluated in Japanese patients.

METHODS

Fifty-three children who received maintenance chemotherapy were enrolled in this study. The scheduled dose of oral 6-MP was 40 mg/m(2) daily and that of oral MTX was 25 mg/m(2) weekly. The doses were adjusted according to white blood cell count (target range, 2.5-3.5 × 10(9) /L) and aspartate aminotransferase and alanine aminotransferase level (< 750 IU/L). Eight polymorphisms in six candidate genes, TPMT, ITPA, MRP4, MTHFR, RFC1, and SLCO1B1, were genotyped using the Taqman PCR method. Clinical course was reviewed retrospectively from medical records.

RESULTS

The average dose of 6-MP was lower in the patients with at least one variant allele at SLCO1B1 c.521 T > C than in the patients with wild homozygous genotype. The other analyzed polymorphisms were not associated with toxicity, 6-MP, or MTX dose.

CONCLUSIONS

Polymorphism of SLCO1B1 c.521 T > C could be a strong predictor of 6-MP dose reduction in maintenance chemotherapy in childhood ALL.

Xenobiotic sensor- and metabolism-related gene variants in environmental sensitivity-related illnesses: a survey on the Italian population

In the environmental sensitivity-related illnesses (SRIs), multiple chemical sensitivity (MCS), chronic fatigue syndrome (FCS), and fibromyalgia (FM), the search for genetic polymorphisms of phase I/II xenobiotic-metabolizing enzymes as suitable diagnostic biomarkers produced so far inconclusive results, due to patient heterogeneity, geographic/ethnic differences in genetic backgrounds, and different methodological approaches. Here, we compared the frequency of gene polymorphisms of selected cytochrome P450 (CYP) metabolizing enzymes and, for the first time, the frequency of the xenobiotic sensor Aryl hydrocarbon receptor (AHR) in the three cohorts of 156 diagnosed MCS, 94 suspected MCS, and 80 FM/FCS patients versus 113 healthy controls. We found significantly higher frequency of polymorphisms CYP2C9∗2, CYP2C9∗3, CYP2C19∗2, CYP2D6∗4 and CYP2D6∗41 in patients compared with controls. This confirms that these genetic variants represent a genetic risk factor for SRI. Moreover, the compound heterozygosity for CYP2C9∗2 and ∗3 variants was useful to discriminate between either MCS or FM/CFS versus SMCS, while the PM ∗41/∗41 genotype discriminated between MCS and either SMCS or FM/CFS. The compound heterozygosity for CYP2C9 ∗1/∗3 and CYP2D6 ∗1/∗4 differentiated MCS and SMCS cases from FM/CFS ones. Interestingly, despite the distribution of the AHR Arg554Lys variant did not result significantly different between SRI cases and controls, it resulted useful for the discrimination between MCS and SMCS cases when considered within haplotypes in combination with CYP2C19 ∗1/∗2 and CYP2D6 ∗1/∗4. Results allowed us to propose the genotyping for these specific CYP variants, together with the AHR Arg554Lys variant, as reliable, cost-effective genetic parameters to be included in the still undefined biomarkers' panel for laboratory diagnosis of the main types of environmental-borne SRI.