Comparative Assessment of SSR and RAPD markers for genetic diversity in some Mango cultivars.

Genetic improvement mainly depends on the level of genetic variability present in the population, and the degree of genetic diversity in a population largely determines the rate of genetic advancement. For analyzing genetic diversity and determining cultivar identities, a molecular marker is a useful tool. Using 30 SSR (simple sequence repeat) and 30 RAPD (randomly amplified polymorphic DNA) markers, this study evaluated the genetic divergence of 17 mango cultivars. The effectiveness of the two marker systems was evaluated using their genetic diversity characteristics. Additionally, the effects of SM (simple matching) and Dice similarity coefficients and their effects on mango clustering were evaluated. The findings showed that SSR markers generated 192 alleles, all of which were polymorphic (100%). With RAPD markers, 434 bands were obtained, 361 of which were polymorphic (83%). The average polymorphic information content (PIC) for RAPD and SSR was 0.378 and 0.735, respectively. Using SSR markers resulted in much higher values for other genetic diversity parameters compared to RAPD markers. Furthermore, grouping the genotypes according to the two similarity coefficients without detailed consideration of these coefficients could not influence the study results. The RAPD markers OPA_01, OPM_12 followed by OPO_12 and SSR markers MIAC_4, MIAC_5 followed by mMiCIR_21 were the most informative in terms of describing genetic variability among the cultivars under study; they can be used in further investigations such as genetic mapping or marker-assisted selection. Overall, 'Zebda' cultivar was the most diverse of the studied cultivars.

Assessment of homozygosity in transgenic plants using selectable markers.

Production of homozygous transgenic plants is a prerequisite for the phenotypic analysis and/or for the commercial release of transgenic plants for cultivation. Here we present a simple protocol for the selection of homozygous transgenics using antibiotics as a selectable marker. The protocol has been used to select homozygous rice transgenic plants using hygromycin antibiotic. However, the described protocol can be used for selction of homozygous in any transgenic plants using a appropriate selectable marker. For complete details on the use and execution of this protocol, please refer to Passricha et al. (2016).1.

Assessment of Plasmodium falciparum anti-malarial drug resistance markers in pfk13-propeller, pfcrt and pfmdr1 genes in isolates from treatment failure patients in Democratic Republic of Congo, 2018-2019.

BACKGROUND: The national policy for malaria treatment of the Democratic Republic of Congo recommends two first-line artemisinin-based combinations for the treatment of uncomplicated malaria: artesunate-amodiaquine and artemether-lumefantrine. This study investigated the presence of markers associated with resistance to the current first-line artemisinin-based combination therapy (ACT) in isolates of Plasmodium falciparum from treatment failure patients in the Democratic Republic of Congo. METHODS: From November 2018 to November 2019, dried blood spots were taken from patients returning to health centres for fever within 28 days after an initial malaria treatment in six sentinel sites of the National Malaria Control Programme across Democratic Republic of Congo. The new episode of malaria was first detected by a rapid diagnostic test and then confirmed by a real-time PCR assay to define treatment failure. Fragments of interest in pfk13 and pfcrt genes were amplified by conventional PCR before sequencing and the Pfmdr1 gene copy number was determined by a TaqMan real-time PCR assay. RESULTS: Out of 474 enrolled patients, 364 (76.8%) were confirmed positive by PCR for a new episode of P. falciparum malaria, thus considered as treatment failure. Of the 325 P. falciparum isolates obtained from 364 P. falciparum-positive patients and successfully sequenced in the pfk13-propeller gene, 7 (2.2%) isolates carried non-synonymous mutations, among which 3 have been previously reported (N498I, N554K and A557S) and 4 had not yet been reported (F506L, E507V, D516E and G538S). Of the 335 isolates successfully sequenced in the pfcrt gene, 139 (41.5%) harboured the K76T mutation known to be associated with chloroquine resistance. The SVMNT haplotype associated with resistance to amodiaquine was not found. None of the isolates carried an increased copy number of the pfmdr1 gene among the 322 P. falciparum isolates successfully analysed. CONCLUSION: No molecular markers currently known to be associated with resistance to the first-line ACT in use were detected in isolates of P. falciparum from treatment failure patients. Regular monitoring through in vivo drug efficacy and molecular studies must continue to ensure the effectiveness of malaria treatment in Democratic Republic of Congo.

Development of the decision tree model for distinguishing individuals of Chinese four surnames from Zhanjiang Han population based on Y-STR haplotypes.

Co-separation studies between surnames and Y chromosome genetic markers are beneficial to revealing population migrations, surname origins, population formation histories and forensic familial searching. Genetic distributions of 27 Y-STRs in Chinese four surnames (Li, Lin, Chen and Huang) from Zhanjiang Han population were investigated. Meanwhile, we tried to develop a decision tree model for surname predictions based on Y-STR haplotypes. Allelic frequencies of 27 Y-STRs showed that unique alleles were only observed in a certain surname; besides, some alleles displayed higher frequencies in a certain surname than those in other surnames, implying these alleles might be employed as the useful indicators for surname predictions. Haplotype match probability values of 27 Y-STRs in these surnames revealed that the system could be used as a valuable tool for forensic male identification. The developed decision tree model performed well for the training set with the accuracy of 0.9860 and obtained the relatively high accuracy (>0.70) for surname predictions of the testing set. To sum up, we explored the power of the machine learning to the surname predictions based on obtained Y-STR haplotypes, which showed promising application values in forensic familial searching.

Noninvasive Assessment of Epidermal Genomic Markers of UV Exposure in Skin.

The measurement of UV-induced DNA damage as a dosimeter of exposure and predictor of skin cancer risk has been proposed by multiple groups. Although UV-induced mutations and adducts are present in normal-appearing UV-exposed epidermis, sampling normal nonlesional skin requires noninvasive methods to extract epidermal DNA for analysis. Here, we demonstrate the feasibility of such an approach, termed surfactant-based tissue acquisition for molecular profiling. Sampling in patients was performed using a felt-tip pen soaked in a mixture of surfactants (Brij-30/N-decyl-N,N-dimethyl-3-ammonio-1-propanesulfonate). In mice, we show that the epidermis can be selectively removed without scarring, with complete healing within 2 weeks. We exposed hairless mice to low-dose UV radiation over a period of 3 months and serially sampled them through up to 2 months following the cessation of UV exposure, observing a progressive increase in a UV signature mutational burden. To test whether surfactant-based tissue acquisition for molecular profiling could be applied to human patients, samples were collected from sun-exposed and sun-protected areas, which were then subjected to high-depth targeted exome sequencing. Extensive UV-driven mosaicism and substantially increased mutational loads in sun-exposed versus sun-protected areas were observed, suggesting that genomic measures, as an integrated readout of DNA damage, repair, and clonal expansion, may be informative markers of UV exposure.

Genetic Diversity Assessment and Marker-Assisted Selection in Crops.

Global warming is negatively impacting on crop yield and Earth's climate changes can bring possible negative effects on the growth and reproductive success of crops [...].

Comparative assessment of genetic diversity matrices and clustering methods in white Guinea yam (Dioscorea rotundata) based on morphological and molecular markers.

Understanding the diversity and genetic relationships among and within crop germplasm is invaluable for genetic improvement. This study assessed genetic diversity in a panel of 173 D. rotundata accessions using joint analysis for 23 morphological traits and 136,429 SNP markers from the whole-genome resequencing platform. Various diversity matrices and clustering methods were evaluated for a comprehensive characterization of genetic diversity in white Guinea yam from West Africa at phenotypic and molecular levels. The translation of the different diversity matrices from the phenotypic and genomic information into distinct groups varied with the hierarchal clustering methods used. Gower distance matrix based on phenotypic data and identity by state (IBS) distance matrix based on SNP data with the UPGMA clustering method found the best fit to dissect the genetic relationship in current set materials. However, the grouping pattern was inconsistent (r = - 0.05) between the morphological and molecular distance matrices due to the non-overlapping information between the two data types. Joint analysis for the phenotypic and molecular information maximized a comprehensive estimate of the actual diversity in the evaluated materials. The results from our study provide valuable insights for measuring quantitative genetic variability for breeding and genetic studies in yam and other root and tuber crops.

Assessment of genetic diversity and genetic relationships of farm and laboratory quail populations in Japan using microsatellite DNA markers.

BACKGROUND: The Japanese quail (Coturnix japonica) is an important poultry species owing to their high economic efficiency and biological advantages. The genetic diversity of farm quail populations has rarely been studied. OBJECTIVES: This study aimed to assess the genetic diversity of farm quail populations and their genetic relationships, which could provide important information for designing breeding programmes to maintain egg and/or meat production efficiency. METHODS: Molecular phylogenetic and STRUCTURE analyses were conducted for seven farm populations and six laboratory lines using 50 microsatellite markers previously developed by us. RESULTS: The genetic diversity within each farm population was relatively high despite long-term breeding within closed colonies. However, the genetic variation between populations was absent. Twenty highly polymorphic markers, selected based on Ne, He and FST values, enabled the construction of reliable phylogenetic trees and STRUCTURE plots. CONCLUSIONS: In the farm populations analysed in the present study, gene flow between genetically distant populations is needed to restore genetic diversity between farm populations, which could exploit heterosis and decrease the risk of inbreeding depression. Our findings demonstrate that these markers are useful for examining the genetic structure of farm quail populations.

Microsatellite based DNA fingerprinting and assessment of genetic diversity in bougainvillea cultivars.

Novel microsatellite markers were developed to investigate the genetic diversity and DNA fingerprinting of bougainvillea cultivars. Total of 175 SSRs were designed from over 50,000 SSRs identified in the whole genome sequence data, 33 highly polymorphic markers were identified. These selected SSRs produced a total of 165 alleles with 2 (BOUG-3 and BOUG-50) to 9 (BOUG-69) alleles per loci with an average of 5 alleles per locus. The overall size of the amplified products ranged from 90 bp (BOUG-51 and BOUG-81) to 320 bp (BOUG-162). The gene diversity per locus ranged from 0.13 to 0.91 with a mean of 0.71. Primer BOUG-73 and BOUG-124 exhibited highest gene diversity with greater number of alleles. The mean Nei's genetic diversity index was 0.678 with range of 0.134 (BOUG-77) to 0.958 (BOUG-69). The UPGMA based dendrogram divided the cultivars into seven major clusters. Clustering pattern was more distinct for bract types and variegated cultivars which were also confirmed by PCA scatter plot diagram. The pair-wise genetic distance estimates ranged from 0.089 to 0.86 with an average of 0.56. Each of the 125 cultivar profiled had unique marker profile indicating that the SSR markers identified are useful for identification and differentiation of bougainvillea cultivars. These informative markers identified from the study will be of great utility to assess the genetic diversity, understanding the population structure and in marker assisted breeding for improvement of bougainvillea.

DNA quantitation and degradation assessment: a quantitative PCR protocol designed for small forensic genetics laboratories.

For over 10 years, quantitative PCR (qPCR) for DNA quantitation has been reported in forensics. However, assays have not been described for small qPCR platforms. Thus, technological advancement is not always implemented in small forensic genetics laboratories. A duplex qPCR assay is reported, using a StepOne instrument and targeting a short and a long human DNA region. This study was performed according to international validation guidelines, including sensitivity, repeatability, reproducibility, precision, accuracy, contamination assessment, known and case-type samples, and degradation studies. Characterization of the genetic markers, species specificity, and population studies had already been conducted. Moreover, case-type samples were quantified, amplified using commercial kits and the number of alleles detected was recorded. Sensitivity was shown to be 10 pg/µL. Standard curve replicates demonstrated the assay is accurate, precise, as well as fairly repeatable and reproducible. The NGM Detect kit was shown to yield higher peaks than Identifiler Plus and NGM Select for degraded samples. Moreover, quality sensors were always present and proved useful. The quantification values of the large target showed a correlation with the number of alleles detected in the STR profiles for known and casework samples. The degradation index was shown to be informative, with a value of 10 or higher indicating dropout. It is suggested that after quantitation, samples with low or degraded DNA be amplified using newer amplification kits containing quality sensors to confirm that the low-quality profile was not affected by inhibition.

Assessment of Plasmodium falciparum drug resistance molecular markers from the Blue Nile State, Southeast Sudan.

BACKGROUND: Plasmodium falciparum malaria is a public health problem worldwide. Malaria treatment policy has faced periodic changes due to emergence of drug resistant parasites. In Sudan chloroquine has been replaced by artesunate and sulfadoxine/pyrimethamine (AS/SP) in 2005 and to artemether-lumefantrine (AL) in 2017, due to the development of drug resistance. Different molecular markers have been used to monitor the status of drug resistant P. falciparum. This study aimed to determine the frequency of malaria drug resistance molecular markers in Southeast Sudan. METHODS: The samples of this study were day zero dried blood spot samples collected from efficacy studies in the Blue Nile State from November 2015 to January 2016. A total of 130 samples were amplified and sequenced using illumina Miseq platform. The molecular markers included were Pfcrt, Pfmdr1, Pfdhfr, Pfdhps, Pfk13, exonuclease and artemisinin resistant (ART-R) genetic background (Pfmdr2, ferroredoxine, Pfcrt and Pfarps10). RESULTS: Resistance markers for chloroquine were detected in 25.8% of the samples as mutant haplotype Pfcrt 72-76 CVIET and 21.7% Pfmdr1 86Y. Pfdhfr mutations were detected in codons 51, 59 and 108. The ICNI double-mutant haplotype was the most prevalent (69%). Pfdhps mutations were detected in codons 436, 437, 540, 581 and 613. The SGEGA triple-mutant haplotype was the most prevalent (43%). In Pfdhfr/Pfdhps combined mutation, quintuple mutation ICNI/SGEGA is the most frequent one (29%). Six of the seven treatment failure samples had quintuple mutation and the seventh was quadruple. This was significantly higher from the adequately responsive group (P < 0.01). Pfk13 novel mutations were found in 7 (8.8%) samples, which were not linked to artemisinin resistance. Mutations in ART-R genetic background genes ranged from zero to 7%. Exonuclease mutation was not detected. CONCLUSION: In this study, moderate resistance to chloroquine and high resistance to SP was observed. Novel mutations of Pfk13 gene not linked to treatment failure were described. There was no resistance to piperaquine the partner drug of dihydroartemisinin/piperaquine (DHA-PPQ).

Enhancing Genetic Gain through Genomic Selection: From Livestock to Plants.

Although long-term genetic gain has been achieved through increasing use of modern breeding methods and technologies, the rate of genetic gain needs to be accelerated to meet humanity's demand for agricultural products. In this regard, genomic selection (GS) has been considered most promising for genetic improvement of the complex traits controlled by many genes each with minor effects. Livestock scientists pioneered GS application largely due to livestock's significantly higher individual values and the greater reduction in generation interval that can be achieved in GS. Large-scale application of GS in plants can be achieved by refining field management to improve heritability estimation and prediction accuracy and developing optimum GS models with the consideration of genotype-by-environment interaction and non-additive effects, along with significant cost reduction. Moreover, it would be more effective to integrate GS with other breeding tools and platforms for accelerating the breeding process and thereby further enhancing genetic gain. In addition, establishing an open-source breeding network and developing transdisciplinary approaches would be essential in enhancing breeding efficiency for small- and medium-sized enterprises and agricultural research systems in developing countries. New strategies centered on GS for enhancing genetic gain need to be developed.

Genetic characterization and assessment of diversity in Pandharpuri buffalo breed of India using heterologous microsatellite markers.

The present study was aimed at genetic characterization and diversity analysis of Pandharpuri buffalo population using the Food and Agriculture Organization (FAO) recommended bovine microsatellite markers. Genomic DNA was isolated from blood samples of 50 unrelated animals and a total of 23 microsatellite loci were amplified using polymerase chain reaction. Among 23 recommended microsatellite markers, 14 markers (BM2113, BM1818, CSSM66, HEL13, INRA037, ILSTS05, HAUT27, INRA023, INRA035, HEL5, ETH3, NRA063, MM12 and ETH10) were found to be highly polymorphic in Pandharpuri population. The amplified products were run on polyacrylamide gel electrophoresis (PAGE) apparatus along with a ladder; subsequently, the allele typing was done based on silver staining of the gel. The effective and observed number of alleles, heterozygosity (expected and unbiased) estimates and polymorphic information content (PIC) levels were estimated for each locus. A total of 87 alleles were secured for 14 polymorphic loci studied giving an overall average of 6.21 alleles per locus. The number of alleles ranged from 2 (INRA063) to 9 (BM1818 and HEL13). The mean effective number of alleles across all polymorphic loci was found to be 4.28. The overall mean expected heterozygosity and unbiased expected heterozygosity values were 0.77 and 0.76, ranging from 0.50 (INRA063) to 0.88 (BM1818) and 0.50 (INRA063) to 0.88 (BM1818), respectively. The average PIC estimate across all polymorphic loci was 0.73 ranging from 0.373 (INRA063) to 0.864 (BM1818). In the present study, the characterization and diversity estimates are reported for Pandharpuri population. It was found to maintain optimum diversity based on 14 polymorphic microsatellite markers.

Unveiling the guidance heterogeneity for genome-informed drug treatment interventions among regulatory bodies and research consortia.

Pharmacogenomics and personalized medicine interventions hold promise to optimize drug treatment modalities and hence, improve the quality of life of the patients by minimizing the occurrence of adverse drug reactions and/or maximizing drug treatment efficacy. To this end, proper guidance for accurately prescribing the correct drug at the right dose is empowered by major regulatory bodies, namely the U.S. Food and Drug Administration (FDA) and the European Medicine Agency (EMA), and well-recognized research consortia, like the Clinical Pharmacogenetics Implementation Consortium (CPIC), that propose therapeutic recommendations after the thorough evaluation of the existing scientific evidence base. In this context, the consistency of these recommendations is crucial for smoothly integrating pharmacogenomics into the clinic. Here, we collected all of the important and clinically actionable pharmacogenomics information provided by the aforementioned renowned sources and documented it in order to assess potential similarities and, most importantly, differences. Our data show that the level of concordance regarding the guidance provided for the same drug-gene association pairs varies significantly, despite the fact that it all derives from a single evidence base. In particular, apart from the expected similarities in a number of association pairs, especially the ones related to cancer genomics, there are still major discrepancies that create confusion as to which guidance should be followed in order to properly inform drug prescribing. This regulatory deficiency calls for the fruitful engagement of the regulatory agencies involved with the contribution of other experts engaged in the field of pharmacogenomics in an effort to harmonize the existing arsenal of guidance for genome-informed drug prescription. The achievement of harmonization would in turn expedite bringing personalized medicine closer to clinical fruition.

DNA fingerprinting and assessment of some physiological changes in Al-induced Bryophyllum daigremontianum clones.

Aluminum (Al) is one of the most important stress factors that reduce plant productivity in acidic soils. Present work thereby analyzed Al-induced genomic alterations in Bryophyllum daigremontianum clones using RAPD and ISSR markers, and investigated responding changes in photosynthetic pigment (chlorophyll a, b, a/b, total chlorophyll and carotenoid) contents and total soluble protein amounts in plant leaves. The main reason for the use of bulbiferous spurs originated clone plants was to increase reliability and acceptability of RAPD and ISSR techniques in DNA fingerprinting. Raised 40 clone plants were divided into five separate groups each with eight individuals and each experimental group was watered with 0 (control), 0 (acid control), 50, 100 and 200 µM AlCl3-containing Hoagland solutions on alternate days for two and a half months. All plant soils except control group were sprayed with 0.2% sulfuric acid following watering days and this contributed acidic characteristic (pH 4.8) to soil structure. Increase in Al concentrations were accompanied by an increase in total soluble protein amounts, a decrease in photosynthetic pigment contents, and with appearance, disappearance and intensity changes at RAPD and ISSR band profiles. Out of tested RAPD1-25 and ISSR1-15 primers, RAPD8, RAPD9, ISSR2 and ISSR7 primers produced reproducible band profiles that were distinguishable between treatment and control groups. Findings showed that RAPD and ISSR fingerprints have been useful biomarkers for investigation of plant genotoxicity, especially in clone plants. Moreover, if these fingerprints are integrated with other physiological parameters they could become more powerful tools in ecotoxicology.

An assessment of true and false positive detection rates of stepwise epistatic model selection as a function of sample size and number of markers.

Association studies have been successful at identifying genomic regions associated with important traits, but routinely employ models that only consider the additive contribution of an individual marker. Because quantitative trait variability typically arises from multiple additive and non-additive sources, utilization of statistical approaches that include main and two-way interaction marker effects of several loci in one model could lead to unprecedented characterization of these sources. Here we examine the ability of one such approach, called the Stepwise Procedure for constructing an Additive and Epistatic Multi-Locus model (SPAEML), to detect additive and epistatic signals simulated using maize and human marker data. Our results revealed that SPAEML was capable of detecting quantitative trait nucleotides (QTNs) at sample sizes as low as n = 300 and consistently specifying signals as additive and epistatic for larger sizes. Sample size and minor allele frequency had a major influence on SPAEML's ability to distinguish between additive and epistatic signals, while the number of markers tested did not. We conclude that SPAEML is a useful approach for providing further elucidation of the additive and epistatic sources contributing to trait variability when applied to a small subset of genome-wide markers located within specific genomic regions identified using a priori analyses.

Assessment and application of host-specific Bacteroidales genetic markers for microbial source tracking of river water in Japan.

Microbial source tracking using host-specific microbial genetic markers is considered a promising approach to determine fecal contamination sources of aquatic environments. This study aimed to assess the application of previously developed host-specific Bacteroidales quantitative PCR assays to microbial source tracking of river water samples in Yamanashi Prefecture, Japan. Various types of fecal-source samples, such as raw sewage, secondary-treated sewage of a wastewater treatment plant, and cattle feces, were used for three human-, two ruminant- and two pig-specific Bacteroidales quantitative PCR assays. Our results demonstrated that BacHum, BacR and Pig2Bac assays as suitable human-, ruminant- and pig-specific assays, with an accuracy of 86%, 94% and 77%, respectively. These selected assays were used for microbial source tracking of 63 river water samples collected at nine sites in two river basins. From these sites, there were 48 (76%), 34 (54%) and 9 (14%) positive samples using the BacHum, BacR and Pig2Bac assays, respectively. These assays revealed the effects of humans and animals on fecal contamination of river water.

Consensus assessment of the contamination level of publicly available cyanobacterial genomes.

Publicly available genomes are crucial for phylogenetic and metagenomic studies, in which contaminating sequences can be the cause of major problems. This issue is expected to be especially important for Cyanobacteria because axenic strains are notoriously difficult to obtain and keep in culture. Yet, despite their great scientific interest, no data are currently available concerning the quality of publicly available cyanobacterial genomes. As reliably detecting contaminants is a complex task, we designed a pipeline combining six methods in a consensus strategy to assess the contamination level of 440 genome assemblies of Cyanobacteria. Two methods are based on published reference databases of ribosomal genes (SSU rRNA 16S and ribosomal proteins), one is indirectly based on a reference database of marker genes (CheckM), and three are based on complete genome analysis. Among those genome-wide methods, Kraken and DIAMOND blastx share the same reference database that we derived from Ensembl Bacteria, whereas CONCOCT does not require any reference database, instead relying on differences in DNA tetramer frequencies. Given that all the six methods appear to have their own strengths and limitations, we used the consensus of their rankings to infer that >5% of cyanobacterial genome assemblies are highly contaminated by foreign DNA (i.e., contaminants were detected by 5 or 6 methods). Our results will help researchers to check the quality of publicly available genomic data before use in their own analyses. Moreover, we argue that journals should make mandatory the submission of raw read data along with genome assemblies in order to facilitate the detection of contaminants in sequence databases.

Consequences of Biomarker Analysis on the Cost-Effectiveness of Cetuximab in Combination with FOLFIRI as a First-Line Treatment of Metastatic Colorectal Cancer: Personalised Medicine at Work.

BACKGROUND: Therapies may be more efficacious when targeting a patient subpopulation with specific attributes, thereby enhancing the cost-effectiveness of treatment. In the CRYSTAL study, patients with metastatic colorectal cancer (mCRC) were treated with cetuximab plus FOLFIRI or FOLFIRI alone until disease progression, unacceptable toxic effects or withdrawal of consent. OBJECTIVE: To determine if stratified use of cetuximab based on genetic biomarker detection improves cost-effectiveness. METHODS: We used individual patient data from CRYSTAL to compare the cost-effectiveness, cost per life-year (LY) and cost per quality-adjusted LY (QALY) gained of cetuximab plus FOLFIRI versus FOLFIRI alone in three cohorts of patients with mCRC: all randomised patients (intent-to-treat; ITT), tumours with no detectable mutations in codons 12 and 13 of exon 2 of the KRAS protein ('KRAS wt') and no detectable mutations in exons 2, 3 and 4 of KRAS and exons 2, 3 and 4 of NRAS ('RAS wt'). Survival analysis was conducted using RStudio, and a cost-utility model was modified to allow comparison of the three cohorts. RESULTS: The deterministic base-case ICER (cost per QALY gained) was £130,929 in the ITT, £72,053 in the KRAS wt and £44,185 in the RAS wt cohorts for cetuximab plus FOLFIRI compared with FOLFIRI alone. At a £50,000 willingness-to-pay threshold, cetuximab plus FOLFIRI has a 2.8, 20 and 63% probability of being cost-effective for the ITT, KRAS wt and RAS wt cohorts, respectively, versus FOLFIRI alone. CONCLUSION: Screening for mutations in both KRAS and NRAS may provide the most cost-effective approach to patient selection.