Dihydropyrimidine Dehydrogenase Gene Research Articles

Approach for Phased Sequence-Based Genotyping of the Critical Pharmacogene Dihydropyrimidine Dehydrogenase (DPYD).

Pre-treatment genotyping of four well-characterized toxicity risk-variants in the dihydropyrimidine dehydrogenase gene (DPYD) has been widely implemented in Europe to prevent serious adverse effects in cancer patients treated with fluoropyrimidines. Current genotyping practices are largely limited to selected commonly studied variants and are unable to determine phasing when more than one variant allele is detected. Recent evidence indicates that common DPYD variants modulate the functional impact of deleterious variants in a phase-dependent manner, where a cis- or a trans-configuration translates into different toxicity risks and dosing recommendations. DPYD is a large gene with 23 exons spanning nearly a mega-base of DNA, making it a challenging candidate for full-gene sequencing in the diagnostic setting. Herein, we present a time- and cost-efficient long-read sequencing approach for capturing the complete coding region of DPYD. We demonstrate that this method can reliably produce phased genotypes, overcoming a major limitation with current methods. This method was validated using 21 subjects, including two cancer patients, each of whom carried multiple DPYD variants. Genotype assignments showed complete concordance with conventional approaches. Furthermore, we demonstrate that the method is robust to technical challenges inherent in long-range sequencing of PCR products, including reference alignment bias and PCR chimerism.

Germline cis variant determines epigenetic regulation of the anti-cancer drug metabolism gene dihydropyrimidine dehydrogenase (DPYD)

Enhancers are critical for regulating tissue-specific gene expression, and genetic variants within enhancer regions have been suggested to contribute to various cancer-related processes, including therapeutic resistance. However, the precise mechanisms remain elusive. Using a well-defined drug-gene pair, we identified an enhancer region for dihydropyrimidine dehydrogenase (DPD, DPYD gene) expression that is relevant to the metabolism of the anti-cancer drug 5-fluorouracil (5-FU). Using reporter systems, CRISPR genome-edited cell models, and human liver specimens, we demonstrated in vitro and vivo that genotype status for the common germline variant (rs4294451; 27% global minor allele frequency) located within this novel enhancer controls DPYD transcription and alters resistance to 5-FU. The variant genotype increases recruitment of the transcription factor CEBPB to the enhancer and alters the level of direct interactions between the enhancer and DPYD promoter. Our data provide insight into the regulatory mechanisms controlling sensitivity and resistance to 5-FU.

Germline cis variant determines epigenetic regulation of the anti-cancer drug metabolism gene dihydropyrimidine dehydrogenase (DPYD).

Enhancers are critical for regulating tissue-specific gene expression, and genetic variants within enhancer regions have been suggested to contribute to various cancer-related processes, including therapeutic resistance. However, the precise mechanisms remain elusive. Using a well-defined drug-gene pair, we identified an enhancer region for dihydropyrimidine dehydrogenase (DPD, DPYD gene) expression that is relevant to the metabolism of the anti-cancer drug 5-fluorouracil (5-FU). Using reporter systems, CRISPR genome-edited cell models, and human liver specimens, we demonstrated in vitro and vivo that genotype status for the common germline variant (rs4294451; 27% global minor allele frequency) located within this novel enhancer controls DPYD transcription and alters resistance to 5-FU. The variant genotype increases recruitment of the transcription factor CEBPB to the enhancer and alters the level of direct interactions between the enhancer and DPYD promoter. Our data provide insight into the regulatory mechanisms controlling sensitivity and resistance to 5-FU.

Diversity of oncopharmacogenetic profile within Spanish population.

Consensus guidelines for genotype-guided fluoropyrimidine dosing based on variation in the dihydropyrimidine dehydrogenase (DPYD) gene before treatment have been firmly established. The prior pharmacogenetic report avoids the serious toxicity that inevitably occurred in a non-negligible percentage of the treated patients. The precise description of the allelic distribution of the variants of interest in our reference populations is information of great interest for the management of the prescription of these antineoplastic drugs. We characterized the allelic distribution of the UGT1A1*28 variant (rs3064744), as well as the DPYD*2A (rs3918290) variant, c.1679T>G (rs55886062), c.2846A>T (rs67376798) and c.1129-5923C>G (rs75017182; HapB3) in series of 5251 patients who are going to receive treatment with irinotecan and fluoropyrimidines, representative of Valencian, Aragonese and Western Andalusian populations.

Dihydropyrimidine dehydrogenase gene variants for predicting grade 4-5 fluoropyrimidine-induced toxicity: FUSAFE individual patient data meta-analysis.

Dihydropyrimidine dehydrogenase (DPD) deficiency is the main known cause of life-threatening fluoropyrimidine (FP)-induced toxicities. We conducted a meta-analysis on individual patient data to assess the contribution of deleterious DPYD variants *2A/D949V/*13/HapB3 (recommended by EMA) and clinical factors, for predicting G4-5 toxicity. Study eligibility criteria included recruitment of Caucasian patients without DPD-based FP-dose adjustment. Main endpoint was 12-week haematological or digestive G4-5 toxicity. The value of DPYD variants *2A/p.D949V/*13 merged, HapB3, and MIR27A rs895819 was evaluated using multivariable logistic models (AUC). Among 25 eligible studies, complete clinical variables and primary endpoint were available in 15 studies (8733 patients). Twelve-week G4-5 toxicity prevalence was 7.3% (641 events). The clinical model included age, sex, body mass index, schedule of FP-administration, concomitant anticancer drugs. Adding *2A/p.D949V/*13 variants (at least one allele, prevalence 2.2%, OR 9.5 [95%CI 6.7-13.5]) significantly improved the model (p < 0.0001). The addition of HapB3 (prevalence 4.0%, 98.6% heterozygous), in spite of significant association with toxicity (OR 1.8 [95%CI 1.2-2.7]), did not improve the model. MIR27A rs895819 was not associated with toxicity, irrespective of DPYD variants. FUSAFE meta-analysis highlights the major relevance of DPYD *2A/p.D949V/*13 combined with clinical variables to identify patients at risk of very severe FP-related toxicity.

Frequency and clinical relevance of DPYD genetic variants in gastrointestinal cancer patients

ObjectiveTo determine the prevalence of loss-of-function variants in the dihydropyrimidine dehydrogenase gene in patients with gastrointestinal neoplasms, assess their clinical relevance, and evaluate the implementation of a multidisciplinary circuit at three months from its implementation. MethodThis is a descriptive, observational and retrospective study, which included adult patients with gastrointestinal cancer treated at a tertiary university hospital who underwent dihydropyrimidine dehydrogenase genotyping between September 2019 and December 2020. The variables collected were sex, age, type of cancer, location, stage, treatment received, indication of treatment and degree of toxicity developed during the first three cycles. The genotyped variants were rs3918290 (c.1905+1G>A), rs55886062 (c.1679T>G), rs67376798 (c.2846A>T) and rs75017182 (c.1129-5923C>G). ResultsA total of 115 patients were included. The frequency of heterozygous dihydropyrimidine dehydrogenase variant carriers was 9.6% (11 patients). The most frequently identified variant was rs75017182 (6 patients). The second most common variant was rs67376798 (3 patients), followed by rs3918290 (2 patients). No patients presented with the rs55886062 variant. Two of the dihydropyrimidine dehydrogenase carriers developed grade 3-5 toxicity after the first cycle of a regimen that included fluoropyrimidines. Both received full doses of fluoropyrimidine, since their dihydropyrimidine dehydrogenase genotype was unknown before treatment initiation. None of the dihydropyrimidine dehydrogenase carriers who began treatment with a reduced dose of fluoropyrimidine experienced grade 3-5 toxicity. Since the creation in October 2020 of a multidisciplinary team, with the active participation of hospital pharmacists, the monthly average of dihydropyrimidine dehydrogenase genotyping studies has increased from 6.4 (January-October) to 17.5 (November-December). ConclusionsThe present study shows a relatively high prevalence of loss-of-function variants in the dihydropyrimidine dehydrogenase gene as well as the importance of genotyping such variants before starting a treatment with fluoropyrimidines. Hospital pharmacists can contribute to the implementation of pharmacogenetics in daily clinical practice in a tertiary hospital.

Implementation of upfront DPYD genotyping with a low-cost and high-throughput assay to guide fluoropyrimidine treatment in cancer patients.

Genetic variants in the dihydropyrimidine dehydrogenase (DPYD) gene are associated with reduced dihydropyrimidine dehydrogenase enzyme activity and can cause severe fluoropyrimidine-related toxicity. We assessed the frequency of the four most common and well-established DPYD variants associated with fluoropyrimidine toxicity and implemented a relatively low-cost and high-throughput genotyping assay for their detection. This study includes 457 patients that were genotyped for the DPYD c.1129-5923C>G, c.1679T>G, c.1905 + 1G>A and c.2846A>T variants, either by Sanger sequencing or kompetitive allele specific PCR (KASP) technology. Of these, 172 patients presented toxicity during treatment with fluoropyrimidines (post-treatment group), and 285 were tested before treatment (pretreatment group). Heterozygous DPYD variants were identified in 7.4% of the entire series of 457 patients, being the c.2846A>T the most frequent variant. In the post-treatment group, 15.7% of the patients presented DPYD variants, whereas only 2.5% of the patients in the pretreatment group presented a variant. The KASP assays designed in this study presented 100% genotype concordance with the results obtained by Sanger sequencing. The combined assessment of the four DPYD variants in our population increases the identification of patients at high risk for developing fluoropyrimidine toxicity, supporting the upfront routine implementation of DPYD variant genotyping. Furthermore, the KASP genotyping assay described in this study presents a rapid turnaround time and relatively low cost, making upfront DPYD screening feasible in clinical practice.

Allelic Frequency of DPYD Genetic Variants in Patients With Cancer in Spain: The PhotoDPYD Study.

Identifying polymorphisms in the dihydropyrimidine dehydrogenase (DPYD) gene is gaining importance to be able to predict fluoropyrimidine-associated toxicity. The aim of this project was to describe the frequency of the DPYD variants DPYD*2A (rs3918290); c.1679T>G (rs55886062); c.2846A>T (rs67376798) and c.1129-5923C>G (rs75017182; HapB3) in the Spanish oncological patients. Cross-sectional and multicentric study (PhotoDPYD study) conducted in hospitals located in Spain designed to register the frequency of the most relevant DPYD genetic variants in oncological patients. All oncological patients with DPYD genotype were recruited in the participant hospitals. The measures determined where the presence or not of the 4 DPYD previously described variants. Blood samples from 8054 patients with cancer from 40 different hospitals were used to determine the prevalence of the 4 variants located in the DPYD gene. The frequency of carriers of one defective DPYD variant was 4.9%. The most frequently identified variant was c.1129-5923C>G (rs75017182) (HapB3), in 2.9%, followed by c.2846A>T (rs67376798) in 1.4%, c.1905 + 1G>A (rs3918290, DPYD*2A) in 0.7% and c.1679T>G (rs55886062) in 0.2% of the patients. Only 7 patients (0.08%) were carrying the c.1129-5923C>G (rs75017182) (HapB3) variant, 3 (0.04%) the c.1905 + 1G>A (rs3918290, DPYD*2A) and one (0.01%) the DPYD c.2846A>T (rs67376798, p.D949V) variant in homozygosis. Moreover, 0.07% were compound heterozygous patients, 3 carrying the DPYD variants DPYD*2A + c.2846A>T, 2 the DPYD c.1129-5923C>G + c.2846A>T and one the DPYD*2A + c.1129-5923C>G variants. Our results demonstrate the relatively high frequency of DPYD genetic variants in the Spanish patient with cancer population, which highlights the relevance of their determination before initiating a fluoropirimidine-containing regimen.

272P Correlation of dihydropyrimidine dehydrogenase gene mutation with toxicity among gastrointestinal cancers (GI) taking 5-fluorouracil-based chemotherapy: Experience from a tertiary cancer center in eastern part of India

5-fluorouracil (5-FU) is a major component of chemotherapy regimens in gastrointestinal (GI) cancers. Mutation in Dihydropyrimidine Dehydrogenase (DPD) gene can cause severe 5-FU related toxicity. Identifying the mutation helps in predicting the toxicity and adjusting dose of 5-FU. Our study assesses and analyze the utility of DPD testing at our center.

DPYD and TYMS polymorphisms as predictors of 5 fluorouracil toxicity in colorectal cancer patients

Colorectal cancer (CRC) is the third most common cancer and the fourth leading cause of cancer death. 5-Fluorouracil (5-FU) is an essential component of systemic chemotherapy for CRC. Our objective was to determine the genotypic frequency of polymorphisms affecting dihydropyrimidine dehydrogenase (DPYD) and thymidylate synthetase (TYMS) genes and to correlate the genetic profile with the toxicity due to 5-FU, also considering nongenetic factors. This is a prospective study that involved 66 patients. We extracted DNA by salting out methods. We carried out the genotyping of the different polymorphisms by simple PCR for the TYMS 5'UTR and by PCR-RFLP for DPYD: 1905 + 1 G > A, 85 T > C, 496 A > G, 1679 T > G, c.483 + 18G > A and the TYMS: 5'UTR VNTR, 5'UTR G > C and 3'UTR. The study of the association of DPYD and TYMS polymorphisms with the various signs of toxicity under 5-FU revealed that the polymorphisms 496 A > G were significantly associated with hepatotoxicity: OR = 3.85 (p = 0.04). In addition, 85 T > C was significantly associated with mucositis and neurotoxicity: OR = 4.35 (p = 0.03), OR = 3.79 (p = 0.02). For TYMS, the only significant association we observed for 5'UTR with vomiting: OR = 3.34 (p = 0.04). The incidence of adverse reactions related to 5-FU appears to be influenced in patients with CRC by the identified DPYD and TYMS gene polymorphisms in the Tunisian population.

Pharmacogenetic Study of the Dihydropyridine Dehydrogenase Gene in Jordanian Patients with Colorectal Cancer.

Several studies have shown an association between 5-fluorouracil toxicity and variations in the dihydropyrimidine dehydrogenase (DPYD) gene. This cross-sectional study aims to elucidate the association between genetic variations in the DPYD gene and 5-fluorouracil toxicity among Jordanians with colorectal cancer (CRC). 80 CRC Patients were recruited to screen for mutations in the DPYD gene using the Sanger sequencing technique. Sequencing results were analyzed using Mutation Surveyor software, and mutational effects were predicted by the Mutation Tester bioinformatics tool. Three reported variants (c.85T>C, c.1740+40A>G, c.1740+39C>T) and one novel (g.97515583_97515584insA) variant were identified in this study. Results showed a significant association between these variants and toxicity to 5-Fluorouracil with P-values 0.002, 0.005, 0.019, 0.017, respectively. However, there was no significant association between variants and cancer free survival. The present study identified several variants in the DPYD gene among Jordanians with colorectal cancer, which are associated with toxicity to 5-Fluorouracil treatment.

Awareness and attitudes of oncology specialists toward dihydropyrimidine dehydrogenase testing in Saudi Arabia.

Fluoropyrimidines (FP) are among the most common class of prescribed anti-neoplastic drugs. This class has severe to moderate toxicity in around 10%-40% of those who take 5-fluorouracil (5-FU) or capecitabine for the treatment of cancer. In practice many patients with severe toxicities from FP use had dihydropyrimidine dehydrogenase (DPD) enzyme deficiency. Several studies have proposed DPD screening before treatment with 5-fluorouracil (5-FU) and capecitabine or other drugs belonging to the FP group. This study aims to assess the level of awareness and attitudes of oncology specialists in Saudi Arabia toward genetic screening for DPD prior to giving FP. This highlights the importance of health guidelines required for implementation in our health care system, as a framework to adopt testing as a regular practice in clinical care. Based on the findings in this study, guidelineshave been suggested for the Middle East North Africa region. A cross-sectional survey study was conducted during 2021 targeting oncologists and clinical pharmacists working in the oncology departments across Saudi Arabia. A total of 130 oncologists and pharmacists completed the questionnaire representing a response rate of 87%. Most of the respondents indicated that they prescribe FP in clinical practice, but 41% of respondents reported that they have never ordered a specific molecular test during their practice. Only 20% of respondents reported that they often screen for DPD deficiency prior to prescribing FP. Significantly higher rates of awareness of potential dihydropyrimidine dehydrogenase gene (DPYD) mutation were observed among respondents in governmental hospitals (81.1% vs. 47.4% in private hospitals), and among those with more years of practice (80.6% if 5 or more years of practice vs. 59.3% if less than 5 years of practice). Also, higher rates of observing the impact of DPD testing were present among respondents with a PharmD (35% vs. 11% for oncologists and 18% for other professions) and among those with 5 or more years of practice (24.6% vs. 7.7% among those with less than 5 years). While in some institutions there is a high level of awareness among oncology specialists in Saudi Arabia regarding the effect of the potentially serious DPD enzyme deficiency as a result of gene mutations, screening for these mutations prior to prescribing FP is not a routine practice in hospitals across the country. The findings of this study should promote personalized medicine with recognition of interpatient variability via DPD testing to manage the risks of FP prescribing more effectively in the Kingdom of Saudi Arabia.

Colon Cancer Pharmacogenetics: A Narrative Review.

Currently, metastatic colon cancer is treated with monotherapeutic regimens such as folinic acid, fluorouracil, and oxaliplatin (FOLFOX), capecitabine and oxaliplatin (CapeOX), and leucovorin, fluorouracil, and irinotecan hydrochloride (FOLFIRI). Other treatments include biological therapies and immunotherapy with drugs such as bevacizumab, panitumumab, cetuximab, and pembrolizumab. After the research, it was found that some mutations make those treatments not as effective in all patients. In this bibliographic review, we investigated the pharmacogenetic explanations for how mutations in the genes coding for rat sarcoma virus (RAS) and rapidly accelerated fibrosarcoma (RAF) reduce the effectiveness of these treatments and allow the continued proliferation of tumors. Furthermore, we note that patients with mutations in the dihydropyrimidine dehydrogenase (DPDY) gene usually require lower doses of therapies such as 5-fluorouracyl (5-FU) and capecitabine to avoid severe adverse effects. Some other mutations in the thymidylate synthase gene (TSYM), methylenetetrahydrofolate reductase gene (MTHFR), and ATP binding cassette transporter B (ABCB1 and ABCB2) affect efficacy and security of the treatments. It is important to address the clinical implication of the oncologist in the study of gene mutations than can influence in the antitumoral response and safety of colon cancer treatments.

Pharmacogenetic testing-guided treatment for oncology: an overview of reviews.

Pharmacogenetics is the relationship between an individual's genetic variations and their response to pharmacological treatment. We conducted an overview of reviews on the use of post-treatment pharmacogenetic testing for oncology, based on clinically relevant gene-drug pairs. We conducted a search on Medline, Embase and Cochrane Library, from their inception to 18 June 2020. We selected six eligible systematic reviews. The most studied drug categories were estrogen agonists/antagonists and fluoropyrimidines associated with cytochrome P450 and dihydropyrimidine dehydrogenase genes (CYP2D6 andDPYD), but many studies were classified as being of critically low or low quality. There is a need for more high-quality primary studies and systematic reviews that assess the risk of bias, with consistent definitions of clinical outcomes to consider the benefits of pharmacogenetic testing for oncology.

Clinical Implementation of DPYD Pharmacogenetic Testing to Prevent Early-Onset Fluoropyrimidine-Related Toxicity in Cancer Patients in Switzerland.

The implementation of pharmacogenetic testing into clinical practice has been a slow process so far. Here, we review the implementation of pre-treatment testing of dihydropyrimidine dehydrogenase gene (DPYD) risk variants to prevent early-onset fluoropyrimidine (FP)-related toxicity in cancer patients in Switzerland based on data of a large Swiss diagnostic center. In January 2017, the Swiss Federal Office of Public Health introduced the reimbursement of DPYD testing by the compulsory health insurance in Switzerland based on evidence for the clinical relevance of DPYD-risk variants and the cost-effectiveness of pre-treatment testing, and on the availability of international guidelines. However, we did not observe a strong increase in DPYD testing at our diagnostic center from 2017 to 2019. Only a low number of DPYD-testing requests (28–42 per year), concerning mostly retrospective investigations of suspected FP-toxicity, were received. In contrast, we observed a 14-fold increase in DPYD testing together with a strong shift from retrospective to pre-treatment test requests upon the release of recommendations for DPYD testing prior to FP-treatment in April 2020 by the European Medicines Agency. This increase was mainly driven by three geographic regions of Switzerland, where partner institutions of previous research collaborations regarding FP-related toxicity are located and who acted as early-adopting institutions of DPYD testing. Our data suggest the important role of early adopters as accelerators of clinical implementation of pharmacogenetic testing by introducing these policies to their working environment and educating health workers from their own and nearby institutions.

Elevated Risk of Fluoropyrimidine-Associated Toxicity in European Patients with DPYD Genetic Polymorphism: A Systematic Review and Meta-Analysis.

Background: Fluoropyrimidine is widely used owing to its clinical efficacy, however, patients with dihydropyrimidine dehydrogenase (DPD) deficiency can experience fluoropyrimidine-associated toxicity. The dihydropyrimidine dehydrogenase (DPYD) gene encodes DPD, and studies suggest that DPYD polymorphisms can result in DPD deficiency. Since there is not a complete consistency of how much the risk of complication is elevated, we aimed to conduct a systematic literature review and a meta-analysis to provide the risk of fluoropyrimidine-associated toxicity in patients with DPYD rs1801160 polymorphism. Methods: We searched for qualifying studies published before October 2021 from PubMed, Web of Science, and EMBASE based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the association between rs1801160 polymorphism and toxicities. A sensitivity analysis using the leave-one-out method was performed on the overall toxicity. Results: The pooled OR for overall toxicity in the patients with A allele was elevated 1.73 times higher than those with the GG genotype (95% CI 1.44–2.07). Sensitivity analysis yielded similar results, showing the robustness of the result. Subjects with variants showed a 2.37-fold increased hematological toxicity (95% CI 1.48–3.81); especially a 1.87-fold increased neutropenia compared to patients with wildtype (95% CI 1.49–2.34). Patients with A allele revealed 1.22 times higher gastrointestinal toxicity compared to those with GG genotype (95% CI 0.93–1.61), and among gastrointestinal toxicity, the risk of diarrhea was elevated 1.43 times higher in those with variants than patients with wildtype (95% CI 1.12–1.83). Conclusions: rs1801160 polymorphism is associated with elevated fluoropyrimidine-associated toxicity. Therefore, rs1801160 can be a potential candidate for DPD deficiency screening prior to fluoropyrimidine-based regimen.

Dihydropyrimidine dehydrogenase (DPD) polymorphisms knocking on the door.

Identifying polymorphisms in the dihydropyrimidine dehydrogenase (DPYD) genes is gaining importance as predictors of fluoropyrimidine-associated toxicity. The recommendation of dose adjustment for chemotherapy guided by the presence of polymorphisms of the DPYD gene can potentially improve treatment safety for a large number of patients, saving lives, avoiding complications and reducing health care costs. This article discusses how personalisation of fluoropyrimidine treatment based on the identification of DPYD variants can mitigate toxicities and be cost effective.

Clinical Relevance of Novel Polymorphisms in the Dihydropyrimidine Dehydrogenase (DPYD) Gene in Patients with Severe Fluoropyrimidine Toxicity: A Spanish Case-Control Study.

Among cancer patients treated with fluoropyrimidines, 10–40% develop severe toxicity. Polymorphism of the dihydropyrimidine dehydrogenase (DPYD) gene may reduce DPD function, the main enzyme responsible for the metabolism of fluoropyrimidines. This leads to drug accumulation and to an increased risk of toxicity. Routine genotyping of this gene, which usually includes DPYD *HapB3, *2A, *13 and c.2846A > T (D949V) variants, helps predict approximately 20–30% of toxicity cases. For DPD intermediate (IM) or poor (PM) metabolizers, a dose adjustment or drug switch is warranted to avoid toxicity, respectively. Societies such as the Spanish Society of Pharmacogenetics and Pharmacogenomics (SEFF), the Dutch Pharmacogenetics Working Group (DPWG) or the Clinical Pharmacogenetics Implementation Consortium (CPIC) and regulatory agencies (e.g., the Spanish Medicines Agency, AEMPS) already recommend DPYD routine genotyping. However, the predictive capacity of genotyping is currently still limited. This can be explained by the presence of unknown polymorphisms affecting the function of the enzyme. In this case-control work, 11 cases of severe fluoropyrimidine toxicity in patients who did not carry any of the four variants mentioned above were matched with 22 controls, who did not develop toxicity and did not carry any variant. The DPYD exome was sequenced (Sanger) in search of potentially pathogenic mutations. DPYD rs367619008 (c.187 A > G, p.Lys63Glu), rs200643089 (c.2324 T > G, p.Leu775Trp) and rs76387818 (c.1084G > A, p.Val362Ile) increased the percentage of explained toxicities to 38–48%. Moreover, there was an intronic variant considered potentially pathogenic: rs944174134 (c.322-63G > A). Further studies are needed to confirm its clinical relevance. The remaining variants were considered non-pathogenic.

The dihydropyrimidine dehydrogenase gene contributes to heritable differences in sleep in mice

Many aspects of sleep are heritable, but only a few sleep-regulating genes have been reported. Here, we leverage mouse models to identify and confirm a previously unreported gene affecting sleep duration-dihydropyrimidine dehydrogenase (Dpyd). Using activity patterns to quantify sleep in 325 Diversity Outbred (DO) mice-a population with high genetic and phenotypic heterogeneity-a linkage peak for total sleep in the active lights off period was identified on chromosome 3 (LOD score= 7.14). Mice with the PWK/PhJ ancestral haplotype at this location demonstrated markedly reduced sleep. Among the genes within the linkage region, available RNA sequencing data in an independent sample of DO mice supported a highly significant expression quantitative trait locus for Dpyd, wherein reduced expression was associated with the PWK/PhJ allele. Validation studies were performed using activity monitoring and EEG/EMG recording in Collaborative Cross mouse strains with and without the PWK/PhJ haplotype at this location, as well as EEG and EMG recording of sleep and wake in Dpyd knockout mice and wild-type littermate controls. Mice lacking Dpyd had 78.4min less sleep during the lights-off period than wild-type mice (p= 0.007; Cohen's d= -0.94). There was no difference in other measured behaviors in knockout mice, including assays evaluating cognitive-, social-, and affective-disorder-related behaviors. Dpyd encodes the rate-limiting enzyme in the metabolic pathway that catabolizes uracil and thymidine to β-alanine, an inhibitory neurotransmitter. Thus, data support β-alanine as a neurotransmitter that promotes sleep in mice.

Dihydropyrimidine dehydrogenase (DPYD) gene c.1627A>G A/G and G/G genotypes are risk factors for lymph node metastasis and distant metastasis of colorectal cancer.

BackgroundDihydropyrimidine dehydrogenase (DPD) acts as the key enzyme catabolizing pyrimidines, and may affect the tumor progression. DPYD gene mutations affect DPD activity. The relationship between DPYD IVS14+1G>A, c.1627A>G, c.85T>C and lymph node metastasis (LNM) and distant metastasis (DM) of colorectal cancer (CRC) was investigated.MethodsA total of 537 CRC patients were enrolled in this study. DPYD polymorphisms were analyzed by polymerase chain reaction (PCR)‐Sanger sequencing. The relationship between DPYD genotypes and clinical features of patients, metastasis of CRC was analyzed.ResultsAbout DPYD c.1627A>G, A/A (57.7%) was the most common genotype, followed by A/G (35.6%), G/G (6.7%) genotypes. In c.85T>C, T/T, T/C, and C/C genotypes are accounted for 83.6%, 16.0%, and 0.4%, respectively. Logistic regression analysis revealed that DPYD c.1627A>G A/G and G/G genotypes in the dominant model (A/G + G/G vs. A/A) were significant risk factors for the LNM (p = 0.029, OR 1.506, 95% CI = 1.048–2.165) and DM (p = 0.039, OR 1.588, 95% CI = 1.041–2.423) of CRC. In addition, DPYD c.1627A>G polymorphism was more common in patients with abnormal serum carcinoembryonic antigen (CEA) (>5 ng/ml) (p = 0.003) or carbohydrate antigen 24–2 (CA24‐2) (>20 U/ml) level (p = 0.015).ConclusionsThe results suggested that DPYD c.1627A>G A/G, G/G genotypes are associated with increased risk of LNM and DM of CRC.