Onvansertib in Combination with FOLFIRI and Bevacizumab in Second-Line Treatment of KRAS-Mutant Metastatic Colorectal Cancer: A Phase Ib Clinical Study.

PURPOSE: Onvansertib is a highly specific inhibitor of polo-like kinase 1 (PLK1), with demonstrated safety in solid tumors. We evaluated, preclinically and clinically, the potential of onvansertib in combination with chemotherapy as a therapeutic option for KRAS-mutant colorectal cancer. PATIENTS AND METHODS: Preclinical activity of onvansertib was assessed (i) in vitro in KRAS wild-type and -mutant isogenic colorectal cancer cells and (ii) in vivo, in combination with irinotecan, in a KRAS-mutant xenograft model. Clinically, a phase Ib trial was conducted to investigate onvansertib at doses 12, 15, and 18 mg/m2 (days 1-5 and 14-19 of a 28-day cycle) in combination with FOLFIRI/bevacizumab (days 1 and 15) in patients with KRAS-mutant metastatic colorectal cancer who had prior oxaliplatin exposure. Safety, efficacy, and changes in circulating tumor DNA (ctDNA) were assessed. RESULTS: In preclinical models, onvansertib displayed superior activity in KRAS-mutant than wild-type isogenic colorectal cancer cells and demonstrated potent antitumor activity in combination with irinotecan in vivo. Eighteen patients enrolled in the phase Ib study. Onvansertib recommended phase II dose was established at 15 mg/m2. Grade 3 and 4 adverse events (AE) represented 15% of all treatment-related AEs, with neutropenia being the most common. Partial responses were observed in 44% of patients, with a median duration of response of 9.5 months. Early ctDNA dynamics were predictive of treatment efficacy. CONCLUSIONS: Onvansertib combined with FOLIFRI/bevacizumab exhibited manageable safety and promising efficacy in second-line treatment of patients with KRAS-mutant metastatic colorectal cancer. Further exploration of this combination therapy is ongoing. See related commentary by Stebbing and Bullock, p. 2005.

Spliceosome mutations are associated with clinical response in a phase 1b/2 study of the PLK1 inhibitor onvansertib in combination with decitabine in relapsed or refractory acute myeloid leukemia.

PLK1 is overexpressed in acute myeloid leukemia (AML). A phase 1b trial of the PLK1 inhibitor onvansertib (ONV) combined with decitabine (DAC) demonstrated initial safety and efficacy in patients with relapsed/refractory (R/R) AML. The current study aimed to identify molecular predictors of response to ONV + DAC in R/R AML patients. A total of 44 R/R AML patients were treated with ONV + DAC and considered evaluable for efficacy. Bone marrow (BM) samples were collected at baseline for genomic and transcriptomic analysis (n = 32). A 10-gene expression signature, predictive of response to ONV + DAC, was derived from the leading-edge genes of gene set enrichment analyses (GSEA). The gene signature was evaluated in independent datasets and used to identify associated mutated genes. Twenty percent of the patients achieved complete remission, with or without hematologic count recovery (CR/CRi), and 32% exhibited a ≥50% reduction in bone marrow blasts. Patients who responded to treatment had elevated mitochondrial function and OXPHOS. The gene signature was not associated with response to DAC alone in an independent dataset. By applying the signature to the BeatAML cohort (n = 399), we identified a positive association between predicted ONV + DAC response and mutations in splicing factors (SF). In the phase 1b/2 trial, patients with SF mutations (SRSF2, SF3B1) had a higher CR/CRi rate (50%) compared to those without SF mutations (9%). PLK1 inhibition with ONV in combination with DAC could be a potential therapy in R/R AML patients, particularly those with high OXPHOS gene expression and SF mutations.

Plk1 Inhibitors and Abiraterone Synergistically Disrupt Mitosis and Kill Cancer Cells of Disparate Origin Independently of Androgen Receptor Signaling.

Abiraterone is a standard treatment for metastatic castrate-resistant prostate cancer (mCRPC) that slows disease progression by abrogating androgen synthesis and antagonizing the androgen receptor (AR). Here we report that inhibitors of the mitotic regulator polo-like kinase-1 (Plk1), including the clinically active third-generation Plk1 inhibitor onvansertib, synergizes with abiraterone in vitro and in vivo to kill a subset of cancer cells from a wide variety of tumor types in an androgen-independent manner. Gene-expression analysis identified an AR-independent synergy-specific gene set signature upregulated upon abiraterone treatment that is dominated by pathways related to mitosis and the mitotic spindle. Abiraterone treatment alone caused defects in mitotic spindle orientation, failure of complete chromosome condensation, and improper cell division independently of its effects on AR signaling. These effects, although mild following abiraterone monotherapy, resulted in profound sensitization to the antimitotic effects of Plk1 inhibition, leading to spindle assembly checkpoint-dependent mitotic cancer cell death and entosis. In a murine patient-derived xenograft model of abiraterone-resistant metastatic castration-resistant prostate cancer (mCRPC), combined onvansertib and abiraterone resulted in enhanced mitotic arrest and dramatic inhibition of tumor cell growth compared with either agent alone. Overall, this work establishes a mechanistic basis for the phase II clinical trial (NCT03414034) testing combined onvansertib and abiraterone in mCRPC patients and indicates this combination may have broad utility for cancer treatment. SIGNIFICANCE: Abiraterone treatment induces mitotic defects that sensitize cancer cells to Plk1 inhibition, revealing an AR-independent mechanism for this synergistic combination that is applicable to a variety of cancer types.

Innate Resistance and Phosphite Treatment Affect Both the Pathogen's and Host's Transcriptomes in the Tanoak-Phytophthora ramorum Pathosystem.

Phosphites have been used to control Sudden Oak Death; however, their precise mode of action is not fully understood. To study the mechanism of action of phosphites, we conducted an inoculation experiment on two open-pollinated tanoak families, previously found to be partially resistant. Stems of treatment group individuals were sprayed with phosphite, and seven days later, distal leaves were inoculated with the Sudden Oak Death pathogen Phytophthora ramorum. Leaves from treated and untreated control plants were harvested before and seven days after inoculation, and transcriptomes of both host and pathogen were analyzed. We found that tanoak families differed in the presence of innate resistance (resistance displayed by untreated tanoak) and in the response to phosphite treatment. A set of expressed genes associated with innate resistance was found to overlap with an expressed gene set for phosphite-induced resistance. This observation may indicate that phosphite treatment increases the resistance of susceptible host plants. In addition, genes of the pathogen involved in detoxification were upregulated in phosphite-treated plants compared to phosphite-untreated plants. In summary, our RNA-Seq analysis supports a two-fold mode of action of phosphites, including a direct toxic effect on P. ramorum and an indirect enhancement of resistance in the tanoak host.

A Microsatellite Analysis Used to Identify Global Pathways of Movement of Phytophthora cinnamomi and the Likely Sources of Wildland Infestations in California and Mexico.

The genetic structure of a sample of isolates of the oomycete plant pathogen Phytophthora cinnamomi from natural and agricultural outbreaks and the long-distance movement of individual genotypes were studied using four microsatellite markers to genotype 159 isolates of Californian, Mexican, and worldwide origins. Allelic profiles identified 75 multilocus genotypes. A STRUCTURE analysis placed them in three groups characterized by different geographic and host ranges, different genic and genotypic diversity, and different reproductive modes. When relationships among genotypes were visualized on a minimum spanning network (MSN), genotypes belonging to the same STRUCTURE group were contiguous, with rare exceptions. A putatively ancestral group 1 had high genic diversity, included all A1 mating type isolates and all Papuan isolates in the sample, was rarely isolated from natural settings in California and Mexico, and was positioned at the center of the MSN. Putatively younger groups 2 and 3 had lower genic diversity, were both neighbors to group 1 but formed two distinct peripherical sectors of the MSN, and were equally present in agricultural commodities and natural settings in Mexico and California. A few genotypes, especially in groups 2 and 3, were isolated multiple times in different locations and settings. The presence of identical genotypes from the same hosts in different continents indicated that long-distance human-mediated movement of P. cinnamomi had occurred. The presence of identical genotypes at high frequencies in neighboring wildlands and agricultural settings suggest that specific commodities may have been the source of recent wild infestations caused by novel invasive genotypes.

Shifting habitats, morphology, and selective pressures: developmental polyphenism in an adaptive radiation of Hawaiian spiders.

Particularly intriguing examples of adaptive radiation are those in which lineages show parallel or convergent evolution, suggesting utilization of similar genetic or developmental pathways. The current study focuses on an adaptive radiation of Hawaiian "spiny-leg" spiders in which diversification is associated with repeated convergent evolution leading to similar sets of ecomorphs on each island. However, two species on the oldest islands in the archipelago exhibit variability, occurring as two different ecomorphs. More derived species on the younger islands show much less variability, any one species displaying a single ecomorph. We measured ecomorphological features within individuals over time to determine the nature of the variability. Then, using transcriptomes, we conducted lineage-based tests for selection under varying models and analyses of gene tree versus species tree incongruencies. Our results provide strong evidence that variability in color in Tetragnatha kauaiensis and T. polychromata is associated with development within individuals (polyphenism). Moreover, a total of 28 loci showed a signature of selection associated with loss of the color-changing phenotype, and 37 loci showed a signature of selection associated with the colonization of a new environment. The results illustrate how developmental polyphenism might provide an avenue for the repeated evolution of ecomorphs during adaptive radiation.

Refinement of the MHC risk map in a scandinavian primary sclerosing cholangitis population.

BACKGROUND: Genetic variants within the major histocompatibility complex (MHC) represent the strongest genetic susceptibility factors for primary sclerosing cholangitis (PSC). Identifying the causal variants within this genetic complex represents a major challenge due to strong linkage disequilibrium and an overall high physical density of candidate variants. We aimed to refine the MHC association in a geographically restricted PSC patient panel. METHODOLOGY/PRINCIPAL FINDINGS: A total of 365 PSC cases and 368 healthy controls of Scandinavian ancestry were included in the study. We incorporated data from HLA typing (HLA-A, -B, -C, -DRB3, -DRB1, -DQB1) and single nucleotide polymorphisms across the MHC (n = 18,644; genotyped and imputed) alongside previously suggested PSC risk determinants in the MHC, i.e. amino acid variation of DRß, a MICA microsatellite polymorphism and HLA-C and HLA-B according to their ligand properties for killer immunoglobulin-like receptors. Breakdowns of the association signal by unconditional and conditional logistic regression analyses demarcated multiple PSC associated MHC haplotypes, and for eight of these classical HLA class I and II alleles represented the strongest association. A novel independent risk locus was detected near NOTCH4 in the HLA class III region, tagged by rs116212904 (odds ratio [95% confidence interval] = 2.32 [1.80, 3.00], P = 1.35×10-11). CONCLUSIONS/SIGNIFICANCE: Our study shows that classical HLA class I and II alleles, predominantly at HLA-B and HLA-DRB1, are the main risk factors for PSC in the MHC. In addition, the present assessments demonstrated for the first time an association near NOTCH4 in the HLA class III region.

De novo characterization of the gene-rich transcriptomes of two color-polymorphic spiders, Theridion grallator and T. californicum (Araneae: Theridiidae), with special reference to pigment genes.

BACKGROUND: A number of spider species within the family Theridiidae exhibit a dramatic abdominal (opisthosomal) color polymorphism. The polymorphism is inherited in a broadly Mendelian fashion and in some species consists of dozens of discrete morphs that are convergent across taxa and populations. Few genomic resources exist for spiders. Here, as a first necessary step towards identifying the genetic basis for this trait we present the near complete transcriptomes of two species: the Hawaiian happy-face spider Theridion grallator and Theridion californicum. We mined the gene complement for pigment-pathway genes and examined differential expression (DE) between morphs that are unpatterned (plain yellow) and patterned (yellow with superimposed patches of red, white or very dark brown). RESULTS: By deep sequencing both RNA-seq and normalized cDNA libraries from pooled specimens of each species we were able to assemble a comprehensive gene set for both species that we estimate to be 98-99% complete. It is likely that these species express more than 20,000 protein-coding genes, perhaps 4.5% (ca. 870) of which might be unique to spiders. Mining for pigment-associated Drosophila melanogaster genes indicated the presence of all ommochrome pathway genes and most pteridine pathway genes and DE analyses further indicate a possible role for the pteridine pathway in theridiid color patterning. CONCLUSIONS: Based upon our estimates, T. grallator and T. californicum express a large inventory of protein-coding genes. Our comprehensive assembly illustrates the continuing value of sequencing normalized cDNA libraries in addition to RNA-seq in order to generate a reference transcriptome for non-model species. The identification of pteridine-related genes and their possible involvement in color patterning is a novel finding in spiders and one that suggests a biochemical link between guanine deposits and the pigments exhibited by these species.

Combining field epidemiological information and genetic data to comprehensively reconstruct the invasion history and the microevolution of the sudden oak death agent Phytophthora ramorum (Stramenopila: Oomycetes) in California.

Understanding the migration patterns of invasive organisms is of paramount importance to predict and prevent their further spread. Previous attempts at reconstructing the entire history of the sudden oak death (SOD) epidemic in California were limited by: (1) incomplete sampling; (2) the inability to include infestations caused by a single genotype of the pathogen; (3) collapsing of non-spatially contiguous yet genetically similar samples into large meta-samples that confounded the coalescent analyses. Here, we employ an intensive sampling coverage of 832 isolates of Phytopthora ramorum (the causative agent of SOD) from 60 California forests, genotyped at nine microsatellite loci, to reconstruct its invasion. By using age of infestation as a constraint on coalescent analyses, by dividing genetically indistinguishable meta-populations into highly-resolved sets of spatially contiguous populations, and by using Bruvo genetic distances for most analyses, we reconstruct the entire history of the epidemic and convincingly show infected nursery plants are the original source for the entire California epidemic. Results indicate that multiple human-mediated introductions occurred in most counties and that further disease sources were represented by large wild infestations. The study also identifies minor introductions, some of them relatively recent, linked to infected ornamental plants. Finally, using archival isolates collected soon after the discovery of the pathogen in California, we corroborate that the epidemic is likely to have resulted form 3 to 4 core founder individuals evolved from a single genotype. This is probably the most complete reconstruction ever completed for an invasion by an exotic forest pathogen, and the approach here described may be useful for the reconstruction of invasions by any clonally reproducing organism with a relatively limited natural dispersal range.

Dense genotyping of immune-related disease regions identifies nine new risk loci for primary sclerosing cholangitis.

Primary sclerosing cholangitis (PSC) is a severe liver disease of unknown etiology leading to fibrotic destruction of the bile ducts and ultimately to the need for liver transplantation. We compared 3,789 PSC cases of European ancestry to 25,079 population controls across 130,422 SNPs genotyped using the Immunochip. We identified 12 genome-wide significant associations outside the human leukocyte antigen (HLA) complex, 9 of which were new, increasing the number of known PSC risk loci to 16. Despite comorbidity with inflammatory bowel disease (IBD) in 72% of the cases, 6 of the 12 loci showed significantly stronger association with PSC than with IBD, suggesting overlapping yet distinct genetic architectures for these two diseases. We incorporated association statistics from 7 diseases clinically occurring with PSC in the analysis and found suggestive evidence for 33 additional pleiotropic PSC risk loci. Together with network analyses, these findings add to the genetic risk map of PSC and expand on the relationship between PSC and other immune-mediated diseases.

Colonization history and population genetics of the color-polymorphic Hawaiian happy-face spider Theridion grallator (Araneae, Theridiidae).

Past geological and climatological processes shape extant biodiversity. In the Hawaiian Islands, these processes have provided the physical environment for a number of extensive adaptive radiations. Yet, single species that occur throughout the islands provide some of the best cases for understanding how species respond to the shifting dynamics of the islands in the context of colonization history and associated demographic and adaptive shifts. Here, we focus on the Hawaiian happy-face spider, a single color-polymorphic species, and use mitochondrial and nuclear allozyme markers to examine (1) how the mosaic formation of the landscape has dictated population structure, and (2) how cycles of expansion and contraction of the habitat matrix have been associated with demographic shifts, including a "quantum shift" in the genetic basis of the color polymorphism. The results show a marked structure among populations consistent with the age progression of the islands. The finding of low genetic diversity at the youngest site coupled with the very high diversity of haplotypes on the slightly older substrates that are highly dissected by recent volcanism suggests that the mosaic structure of the landscape may play an important role in allowing differentiation of the adaptive color polymorphism.

Species Differentiation on a Dynamic Landscape: Shifts in Metapopulation Genetic Structure Using the Chronology of the Hawaiian Archipelago.

Species formation during adaptive radiation often occurs in the context of a changing environment. The establishment and arrangement of populations, in space and time, sets up ecological and genetic processes that dictate the rate and pattern of differentiation. Here, we focus on how a dynamic habitat can affect genetic structure, and ultimately, differentiation among populations. We make use of the chronology and geographical history provided by the Hawaiian archipelago to examine the initial stages of population establishment and genetic divergence. We use data from a set of 6 spider lineages that differ in habitat affinities, some preferring low elevation habitats with a longer history of connection, others being more specialized for high elevation and/or wet forest, some with more general habitat affinities. We show that habitat preferences associated with lineages are important in ecological and genetic structuring. Lineages that have more restricted habitat preferences are subject to repeated episodes of isolation and fragmentation as a result of lava flows and vegetation succession. The initial dynamic set up by the landscape translates over time into discrete lineages. Further work is needed to understand how genetic changes interact with a changing set of ecological interactions amongst a shifting mosaic of landscapes to achieve species formation.

Stabilizing selection maintains exuberant colour polymorphism in the spider Theridion californicum (Araneae, Theridiidae).

Genetically controlled colour polymorphisms provide a physical manifestation of the operation of selection and how this can vary according to the spatial or temporal arrangement of phenotypes, or their frequency in a population. Here, we examine the role of selection in shaping the exuberant colour polymorphism exhibited by the spider Theridion californicum. This species is part of a system in which several distantly related spiders in the same lineage, but living in very different geographical areas, exhibit remarkably convergent polymorphisms. These polymorphisms are characterized by allelic inheritance and the presence of a single common cryptic morph and, in the case of T. californicum and its congener the Hawaiian happy-face spider Theridion grallator, numerous rare patterned morphs. We compare population differentiation estimated from colour phenotypic data to differentiation at neutral amplified fragment length polymorphisms (AFLP) loci and demonstrate that the colour polymorphism appears to be maintained by balancing selection. We also examine the patterns of selection in the genome-wide sample of AFLP loci and compare approaches to detecting signatures of selection in this context. Our results have important implications regarding balancing selection, suggesting that selective agents can act in a similar manner across disparate taxa in globally disjunct locales resulting in parallel evolution of exuberant polymorphism.

Contrasting patterns of hybridization in large house spiders (Tegenaria atrica group, Agelenidae).

The integrity of species is not fixed and may vary geographically. Here we investigate the geographic distributions and interactions of species in the Tegenaria atrica group (Araneae: Agelenidae). Detailed mapping of T. saeva and T. gigantea in England and Wales shows them to be broadly allopatric in southern England with a tightly defined, and possibly long-standing, narrow zone of parapatry in central southern England. In the north of England (Yorkshire), by contrast, the species are broadly sympatric as a result of recent range expansions. GIS techniques are used to map the species distributions and to quantify, we believe for the first time, the intimacy of interspecific interactions. The extent and nature of hybridization in these two areas is examined through regression and multivariate analyses of morphology. We show that the relative incidence of hybridization is much greater in Yorkshire than within the parapatric zone in the south. Clear patterns of asymmetric introgression are observed in both northern and southern England, with a greater impact of T. gigantea on T. saeva than vice versa. We find no sign of morphological reproductive character displacement at the zone of parapatry that might indicate reinforcement, although we cannot exclude more subtle effects, for example via cuticular pheromones. The integrity of these two species seems to be breaking down in northern England, a process that might gain momentum as the gene pools become more similar.

A common haplotype of the annexin A5 (ANXA5) gene promoter is associated with recurrent pregnancy loss.

We sought to verify whether variation in the promoter of the gene encoding placental anticoagulant protein annexin A5 (ANXA5) represents a risk factor for recurrent pregnancy loss (RPL). Sequence analysis of 70 German RPL patients, all known to carry neither factor V Leiden nor a prothrombin mutation, revealed four consecutive nucleotide substitutions in the ANXA5 promoter, which were transmitted as a joint haplotype (M2). Reporter gene assays revealed that M2 reduces the in vitro activity of the ANXA5 promoter to 37-42% of the normal level. The possible relationship between M2 and RPL was evaluated by comparing RPL patients with two independent control groups recruited from the registry of the Institut für Humangenetik in Münster and the PopGen biobank in Kiel, respectively. Carriers of M2 were found to exhibit a > 2-fold higher RPL risk than non-carriers (odds ratio, 2.42; 95% confidence interval, 1.27-4.58) when using unselected controls (PopGen) and an almost 4-fold higher risk when using the Münster 'super-controls', i.e. women with successful pregnancies and no previous history of pregnancy losses (odds ratio, 3.88; 95% confidence interval, 1.98-7.54). This statistically significant association should facilitate the development of improved prognostic algorithms for RPL, involving a more precise assessment of individual disease risks, and provide a guide to offering adequate therapies where relevant.

On the testing load incurred by cascade genetic carrier screening for Mendelian disorders: a brief report.

One criterion to decide to whom molecular genetic carrier testing should be provided is an individual's carrier risk, taking into account his or her affection status and degree of relatedness to an overt carrier. We have derived formulas to calculate the testing load incurred to a public health system following such a cascade screening strategy. While the testing load turns out to be moderate for individual diseases at meaningful risk thresholds (i.e., 1%-5%), a substantial proportion of the population would have to be tested if all known single gene disorders were to be included in a cascade screening program.

PopGen: population-based recruitment of patients and controls for the analysis of complex genotype-phenotype relationships.

OBJECTIVE: Patient samples used for mapping complex human disease genes are unlikely to be representative of the phenotype spectrum of the respective population as a whole. On the other hand, most ongoing prospective studies are probably too small for evaluating polygenic disease markers. DESIGN: Precise estimates of population-specific genotypic risks can be obtained efficiently through the complete ascertainment of patients in a geographically confined area. The PopGen project uses the most northern part of Germany as a target region for such a pursuit. RESULTS: PopGen currently pursues recruitment, sampling and processing activities in close collaboration with a multitude of clinical partners, covering cardiovascular, neuropsychiatric and environmental diseases. CONCLUSION: PopGen has successfully established itself as a large-scale genetic epidemiological project of international recognition.

Extreme heterogeneity in CARD15 and DLG5 Crohn disease-associated polymorphisms between German and Norwegian populations.

The first gene associated with Crohn disease (CD) has been identified as CARD15 (16q12). Three variants, R702W, G908R and 1007fsinsC are strongly and independently associated with the disease. A second gene, conveying a smaller risk for inflammatory bowel disease (IBD), has been identified as DLG5 (10q23). We assess the frequency of the CARD15 SNPs and of the R30Q mutation in DLG5 and their contribution to the development of CD in a cohort of unrelated IBD patients (151 CD, 325 ulcerative colitis (UC)) and healthy controls (236) from South-east Norway (IBSEN cohort). Genotype-based tests of population differentiation using 23 SNPs across CARD15, together with estimates of F(ST), indicated that the German and Norwegian background populations could be differentiated at the CARD15 locus. The Norwegian and German CD samples exhibited particularly strong differentiation at the three predisposing loci and those marking their background haplotype. There were significantly lower frequencies of the CARD15 SNPs and no significant association with CD in the Norwegian samples. Only a marginal association was observed for the subphenotypes ileitis and ileocolitis vs colitis (P=0.048). The population attributable risk percentage (PAR%) for CARD15 variants in the Norwegian cohort is the lowest reported for a European population (1.88%), except Iceland. Similarly, the DLG5 variant showed no association with CD or IBD, however, there was a negative correlation with stricture (P=0.035). The present results are consistent with an emerging pattern of a low frequency of the CARD15 variants in Northern countries where the prevalence of IBD is greatest.

Identification of probable genotyping errors by consideration of haplotypes.

Undetected genotyping errors pose a problem in genetic epidemiological studies, as they may invalidate statistical analysis or reduce its power. Haplotype analysis requires an improved standard of the data, because a haplotype can be inferred correctly only if the genotypes of all its markers are correct. Here, we present a method that identifies probable genotyping errors in trio samples with the help of the estimated haplotype frequency distribution of the sample. If the likelihood of the most likely haplotype explanation depends strongly on just one genotype, in the sense that setting the genotype to be missing leads to a much more likely haplotype explanation, this genotype is considered as a potential genotyping error. We describe a method that systematically searches the whole data set for such potential errors. Based on the haplotype distribution of a real data set, we carry out a simulation study to estimate the sensitivity and specificity of the method. In addition, we apply our approach to the real data set itself. Potentially erroneous genotypes are re-determined via sequencing. The results of both the simulation study and of the application to the real data set show that a considerable proportion of true genotyping errors is detected and that the number of false-positive signals is acceptable. We conclude that it is indeed possible to identify probable genotyping errors by considering haplotypes. The method described here will be part of the next release of our FAMHAP software.