Search Results (998)

Finding signatures of selective sweeps in genomes is a major goal of current population genomics, as it allows estimating the rate of beneficial mutations going to fixation and identifying the genes involved in selection. Models of recurrent selective sweeps traditionally assume that in chromosomal regions of normal recombination rates at most one beneficial allele is on the way to fixation. We review and extend here the theoretical studies on interference between closely linked beneficial mutations suggesting that this assumption may be violated. We show that interference between beneficial mutations may lead to substantially increased fixation times even in chromosomal regions of normal recombination rates. Furthermore, we discuss how interference can be detected in population genomic studies by analyzing genetic footprints of selective sweeps, and search for empirical evidence of interference in published datasets. Full article

Background: Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy, with lymph node metastasis (LNM) being a key predictor of recurrence and poor prognosis. Preoperative detection of LNM remains challenging due to the limitations of imaging modalities, leading to inadequate surgical resection in 20–30% of patients. While immune checkpoint molecules have been implicated in PTC progression, the heterogeneity of CD8⁺ T cell exhaustion subsets and their specific association with LNM remain poorly defined. In this study, we aimed to perform an exploratory characterization of the distinct immune landscape of PTC prone to LNM, with a focus on terminal immune exhaustion, in order to generate hypotheses for improved risk stratification and therapeutic strategies. Methods: Fresh PTC tissues from 40 patients (22 LNM-positive and 18 LNM-negative) were analyzed via flow cytometry (FCM) to quantify immune cell subsets, inflammatory cytokines, and chemokines. Immunohistochemistry (IHC) validated CD45⁺ immune cell infiltration. Transcriptomic and clinical data from 448 PTC patients in The Cancer Genome Atlas (TCGA-PTC) cohort were used for bioinformatic analysis consistent with the observed phenotype, including Gene Set Variation Analysis (GSVA) of terminal exhaustion gene signatures. Results: LNM-positive PTC exhibited a unique inflammatory milieu with significantly elevated IL-6, IL-1ra, CCL5, and IL-9 levels (all p < 0.05) in tumor interstitial fluid. FCM analysis revealed that LNM-positive PTC had increased infiltration of total CD45⁺ immune cells, CD3⁺ T cells, and CD3⁺CD8⁺ T cells (all p < 0.05). Critically, terminally exhausted PD-1^hiTIM-3⁺ CD8⁺ T cells were significantly enriched in LNM-positive PTC (p = 0.022) and positively correlated with extrathyroidal extension (p = 0.044). Additionally, LNM risk was associated with increased CD4⁺ regulatory T (Treg) cell frequency (p = 0.023) and elevated CTLA-4 expression on CD4⁺ T cells (p = 0.047). In TCGA-PTC validation, the terminal exhaustion gene signature was predominantly enriched in LNM-positive (p < 0.0001) and advanced-stage PTC (p < 0.001) and strongly correlated with BRAF mutation (predominantly V600E) (p < 0.0001)—the most common oncogenic driver in aggressive PTC. Conclusions: Our findings suggest a terminal immune exhaustion phenotype (characterized by PD-1^hiTIM-3⁺ CD8⁺ T cells and Treg enrichment) as a potential key feature associated with LNM-prone PTC. This phenotype shows consistency across clinical samples and TCGA datasets, linking BRAF mutation (predominantly V600E) to immune suppression and metastatic potential. These insights provide a novel exploratory immune-based biomarker for LNM risk stratification and support the potential of combining anti-PD-1/TIM-3 therapy with BRAF inhibitors for high-risk PTC, which should be confirmed in future studies. Full article

The Alternative Lengthening of Telomeres (ALT) pathway drives replicative immortality in aggressive malignancies, particularly sarcomas and gliomas. Clinical ALT stratification has relied on screening for structural ATRX and DAXX mutations. However, this genotypic approach fails to capture the dynamic macro-reprogramming required to sustain ALT. Here, we established and validated a 28-gene transcriptomic signature that captures the ALT-associated transcriptomic phenotype of the ALT phenotype. Using multivariate Cox proportional hazards models and time-dependent ROC analyses, we demonstrate that this signature is a robust, independent predictor of poor overall survival in Sarcoma (SARC) and Lower Grade Glioma (LGG) cohorts, outperforming the prognostic value of traditional ATRX/DAXX mutational status. Genomic mapping revealed this transcriptional synchrony is structurally facilitated by non-random focal clustering on Chromosome 8. To deconstruct the machinery driving this lethal phenotype, we employed an integromic approach, synthesizing protein–protein and metabolic flux networks. Topological algorithms prioritized five indispensable hubs: TP53, ATM, ATR, PCNA, and UBE2I. Gene–metabolite profiling identified PCNA as a bottleneck funneling extreme deoxyribonucleotide (dNTP) demand to sustain break-induced telomeric recombination. To translate these vulnerabilities into actionable treatments, we mapped these hubs to a precision pharmacological network. We propose a multi-targeted strategy combining FDA-approved PARP inhibitors to exploit ATR-mediated synthetic lethality, alongside antimetabolites to induce nucleotide starvation. This study redefines ALT risk stratification and provides a data-driven framework to target and treat resistant ALT-positive tumors. Full article

Induced pluripotent stem cells (iPSCs) are prone to genomic instability during prolonged culture, with recurrent chromosomal aberrations conferring selective advantages. Replication stress is a major driver of this instability, yet the repertoire of replication stress-sensitive loci in iPSCs remains largely unexplored. Here, we mapped aphidicolin-sensitive fragile sites (asFS) in three independent iPSC lines using classical cytogenetic break analysis combined with Monte Carlo simulation and MiDAS mapping directly on banded metaphase chromosomes. We identified 28 asFS, which segregated into a highly active Major cluster (8 sites, accounting for 59% of breaks among asFS) and a less active Minor cluster (20 sites). Five universal asFS (9p21, 6q25-26, 20p11-12, 10q22, Xq25) were present in all three lines, representing a fragility signature associated with the pluripotent state, with Xq25 shifting into the Major cluster after correction for X chromosome dosage. Minor asFS showed preferential co-localization with physical breakpoints or minimal overlapping regions of recurrent culture-acquired aberrations, including 20q11.21 (BCL2L1), 1q32 (MDM4), 8q24 (MYC), 17q21 (WNT3-WNT9B), and 18q21 (DCC/FRA18B). MiDAS mapping validated most asFS and revealed additional replication stress-sensitive loci in pericentromeric and subtelomeric regions that are difficult to score by conventional G-banding. Comparison with fragile site maps from other cell types revealed that the iPSC asFS repertoire is distinct in rank order and relative activity, characteristic of the pluripotent state. Collectively, our findings indicate that the asFS repertoire in iPSCs is hierarchically organized into a stable universal core and a variable peripheral component, and suggest that Minor asFS may contribute to, or be associated with, the genesis of culture-acquired rearrangements. This work provides a framework for understanding how replication stress and clonal selection shape the mutational landscape of pluripotent stem cells. Full article

Background/Objective: An analysis of microRNA (miRNA) expression signatures in lung adenocarcinoma (LUAD) harboring EGFR mutations revealed that multiple miRNAs, including miR-126-3p, were suppressed in cancer tissues. This study focused on miR-126-3p and aimed to identify therapeutic target genes regulated by miR-126-3p in LUAD harboring EGFR mutations and evaluate their potential for combination therapy with EGFR tyrosine kinase inhibitors. Methods: The antitumor function of miR-126-3p was analyzed by the ectopic expression of miR-126-3p into LUAD cells with EGFR mutation. The target genes of miR-126-3p were identified through an analysis of the TargetScan, Genecodis 4 and TCGA databases. The Chou–Talalay method was used to determine the potential synergistic effects of selected drug combinations. Results: The expression of miR-126-3p attenuated the malignant transformation of LUAD cells through targeting the “EGFR tyrosine kinase inhibitor resistance pathway”. We focused on AKT2 among the genes involved in this pathway. Capivasertib was recently approved as the first inhibitor of oncogenic AKT signaling. Therefore, we investigated the effect of combination therapy comprising osimertinib and capivasertib on LUAD cell viability. Combination therapy synergistically reduced cell viability in both PC9 and H1975 cells, with combination index values of 0.61 and 0.14, respectively, at Fa = 0.5. Conclusions: Our miRNA-based analysis is an excellent strategy for identifying therapeutic targets that enhance the effects of EGFR inhibitors on LUAD. Full article

Background/Objectives: Endometrial cancer is a heterogeneous malignancy that displays distinct molecular features and clinical behaviors. The molecular profile of endometrial cancer and its relationship with menopausal status, histological subtype, tumor grade, mismatch repair (MMR)/microsatellite instability (MSI) status, co-mutation patterns, and TCGA molecular classification were investigated in the current study. Methods: A total of 81 histopathologically confirmed endometrial cancer cases were retrospectively evaluated. Molecular profiling was performed using a targeted 71-gene NGS panel together with MSI-PCR and mismatch repair (MMR) immunohistochemistry. Because the targeted panel was not designed to detect genome-wide copy-number alterations or comprehensive mutational signatures, molecular subgroup assignment was performed using a surrogate TCGA-inspired molecular classification approach based on POLE mutation status, microsatellite instability (MSI)/Mismatch Repair (MMR) findings, and TP53 alterations. Histological subtypes, tumor grades, menopausal status, and molecular alterations were compared. Results: Of the cases evaluated, 57 (70.4%) were endometrioid and 24 (29.6%) were serous carcinoma. TP53 variations were significantly higher in serous carcinomas compared to endometrioid tumors (66.7% vs. 26.3%; p = 0.001). In endometrioid carcinomas, the mean number of variants increased with advancing tumor grade (Grade 1: 4.44; Grade 2: 9.68; Grade 3: 11.42; p = 0.006). Alterations in BLM, CDC27, MLH3, and MSH3 were more frequently observed in high-grade tumors. In exploratory analyses, no significant differences were detected between the premenopausal and postmenopausal groups regarding total variant load, number of altered genes, MSI status, or the distribution of TCGA-inspired molecular subgroups; however, these comparisons were limited by the small number of premenopausal patients. The most frequent co-mutation was observed between BLM and CDC27 (55.6%). In the TCGA-inspired molecular classification, the most prevalent subgroup was NSMP-proxy (33.3%). Conclusions: Serous and endometrioid endometrial cancers display distinct molecular characteristics. In endometrioid carcinomas, the genomic alteration load increases in parallel with advancing tumor grade. TCGA-inspired molecular classification and co-mutation analyses revealed the prominent molecular heterogeneity of endometrial cancer. In exploratory analyses, no significant differences were detected between the premenopausal and postmenopausal groups regarding total variant load, number of altered genes, MSI status, or the distribution of TCGA-inspired molecular subgroups. However, these findings should be interpreted with caution because of the limited number of premenopausal patients. Given the limited number of premenopausal patients, findings related to menopausal status should be considered exploratory and require validation in larger, independent cohorts. Full article

Breast cancer (BRCA) possesses prominent molecular heterogeneity, where aberrant expression of genes annotated to asparagine metabolism networks drives malignant progression and therapeutic resistance. However, systematic construction of prognostic signatures from a holistic asparagine metabolic pathway perspective remains scarce, limiting the clinical translation of metabolic insights into prognostic tools. We integrated TCGA and GEO BRCA transcriptomic datasets to screen asparagine metabolism-related differentially expressed genes and build a prognostic model. Six biomarkers, SLC35A2, SRD5A2, NT5E, CEL, IFNG and CNR1, were selected via univariate Cox, LASSO and multivariate Cox regression. SRD5A2 and IFNG were enriched in low-risk patients, while the other four genes were upregulated in high-risk subgroups. This signature reliably stratifies patient prognosis, with risk scores correlating strongly with pathway activity, immune infiltration, immune checkpoints, mutation landscapes and drug responsiveness. Bioinformatic results were validated via TCGA cohort analysis, in vitro cellular assays and Western blot. Two in vivo models were established: 4T1 xenografts in 6-week-old BALB/c mice and DMBA/hormone-induced spontaneous breast tumors in 8-week-old SD rats. Tumors were generated by cell injection or DMBA gavage plus cyclic hormone treatment, and tissue sections were processed for immunohistochemistry. Consistent differential expression of the six core genes was validated across all in vitro and in vivo systems. In conclusion, this asparagine metabolism-associated signature offers candidate biomarkers for personalized prognosis and provides preclinical evidence for metabolism-targeted BRCA therapy. Full article

Background: The growing awareness of breast cancer’s molecular diversity has not changed the technical foundations of surgery itself, but it has profoundly reshaped how surgeons think about surgery. Rather than molecular biology prescribing specific surgery, it is the surgeon’s interpretation of biological behavior—tumor subtype, genomic risk, treatment responsiveness—that influences surgical timing, extent, and feasibility. This is particularly important in the developing world, where mastectomy continues to be the default surgery, not always because it is required, but because biological nuance is underutilized in surgical planning. This review integrates existing evidence, guidelines, and real-world clinical experience to show how a surgeon who understands tumor biology can meaningfully expand safe breast conservation, de-escalate axillary surgery, and align operative choices with systemic therapy. In essence, molecular biology becomes a lens through which surgeons can practice more personalized, precise, and less invasive surgery, without compromising oncologic safety. Recent findings: We present evidence-based algorithms focusing on Luminal A, Luminal B, HER2-positive, and triple-negative subtypes, while discussing the nuances of multifocal and multicentric disease, metaplastic histologies, and discordant lesion management. The review addresses axillary management in the molecular era, specifying the appropriateness of sentinel lymph node biopsy, targeted axillary dissection, or completion axillary dissection, and how subtype-specific nodal responses to neoadjuvant therapy can guide de-escalation strategies. Through clinical vignettes, we exemplify how molecular integration into surgical planning can modify clinical courses, enabling oncoplastic conservation in downstaged tumors and justifying definitive resection in chemo-resistant cases. We examine the implications of germline and somatic genetic testing on surgical decision-making, particularly in relation to BRCA1/2 and PALB2 mutation carriers, alongside ethical and practical counseling considerations. Additionally, we review emerging biomarkers—such as circulating tumor DNA and immune and radiomic signatures—and propose research priorities for their incorporation into surgical trials. Conclusions: Effective implementation necessitates enhanced surgeon education, standardized assays, and multidisciplinary coordination to promote equitable access, consistent utilization of biology-driven algorithms, and rigorous quality oversight. This review furnishes breast surgeons with a pragmatic framework for translating molecular knowledge into multidisciplinary, patient-centered care pathways that optimize oncological safety, aesthetic outcomes, and overall quality of life. Full article

Background/Objectives: Juvenile myelomonocytic leukemia (JMML) is a rare, highly aggressive form of pediatric myelodysplastic/myeloproliferative neoplasm characterized by molecular heterogeneity and constitutive activation of the RAS signaling pathway. This study aimed to characterize the mutational landscape, driver genes, mutational signatures, functional pathways, and therapeutic potential of mutated epigenetic regulator genes in JMML. Methods: Tumor and matched buccal swab samples were collected from 35 JMML patients, and whole-exome sequencing was performed. Somatic variants were called with GATK-Mutect2 and annotated with ANNOVAR. maftools and OncodriveCLUST were used for mutational profiling, co-occurrence analysis, driver gene identification, and protein domain mapping. Drug–gene interactions were explored using DGIdb, mutational signatures for genes were characterized by MutationalPatterns, and functional enrichment analysis was performed by the clusterProfiler package. Results: A total of 28 variants were detected in epigenetic regulator genes, with missense mutations being the most common class of variants and a C>T nucleotide substitution pattern being the most frequent. EP300, SETD2, and DNMT3B were the genes most frequently altered, with 8.57% of cases each, followed by ASXL1, BCORL1, ATRX, KMT2A, and TET2 (5.71% each). Driver gene analysis identified ASXL1 as the top candidate driver gene, followed by BCORL1, EP300, and SETD2. Functional enrichment analysis revealed a high number of genes involved in chromatin organization, histone modification, transcriptional regulation, and oncogenic signaling pathways. The mutational signatures identified were SBS5-like, which are dominated by C>T and T>C transitions, indicating endogenous mutational processes. Analysis of drug–gene interactions revealed KMT2A, EP300, and ATRX as the most interconnected and potentially actionable therapeutic targets. Conclusions: This study provides a comprehensive characterization of epigenetic regulator gene alterations in JMML and highlights the importance of epigenetic dysregulation in disease pathogenesis. Full article

Dementia with Lewy bodies (DLB) is increasingly conceptualised not merely as a disorder of neuronal death but as a primary synaptopathy in which the functional collapse of synaptic transmission and plasticity precedes, and predicts, neurodegeneration and clinical decline. Two genetic determinants dominate the heritable risk architecture of DLB: the α-synuclein gene SNCA, in which both copy-number variation and missense mutations exert dose- and conformation-dependent effects, and GBA1, encoding the lysosomal hydrolase glucocerebrosidase (GCase), the single most influential genetic risk factor for the disease. Here we synthesise evidence that these loci converge on a shared pathogenic endpoint—the impairment of activity-dependent synaptic plasticity. We argue that GBA1 loss-of-function and the resulting accumulation of glucosylceramide stabilise specific neurotoxic α-synuclein proteoforms, including soluble oligomers and self-templating conformational strains bearing defined post-translational modifications. These proteoforms are trafficked to, and enriched within, presynaptic terminals, where they disrupt SNARE-complex assembly and synaptic-vesicle dynamics, while postsynaptically they perturb NMDA and AMPA receptor trafficking, dysregulate dendritic calcium, and compromise synaptic mitochondrial bioenergetics. The net consequence is a metaplastic shift away from long-term potentiation (LTP) and toward aberrant long-term depression (LTD), a signature of synaptic failure detectable before frank pathology. We map these molecular events onto disease-relevant circuits—particularly the cholinergic basal forebrain and hippocampal–cortical and thalamocortical networks—and relate them to the defining neuropsychiatric features of DLB, including cognitive fluctuations and recurrent visual hallucinations. Finally, we evaluate emerging therapeutic strategies that target the GBA1–α-synuclein axis and that aim to restore synaptic plasticity directly. Positioning DLB within the framework of genetically determined plasticity deficits clarifies its kinship with other neuropsychiatric disorders and identifies the synapse as the most tractable node for early, disease-modifying intervention. We further examine how GBA1 allele severity and zygosity grade the phenotype, which genetic and environmental factors modify penetrance in carriers, and what distinguishes this synaptopathy from those driven by PSEN1/PSEN2, MAPT, or HTT, and we summarise the therapeutic pipeline—including enzyme augmentation and adeno-associated viral GBA1 gene therapy—that targets it. Full article

Metastatic colorectal cancer remains associated with poor prognosis despite major therapeutic advances, highlighting the need for robust biomarkers to refine treatment selection and monitor disease dynamics. This review summarizes emerging predictive and prognostic biomarkers in metastatic colorectal cancer across molecular and cellular layers, encompassing both tissue and circulating biomarkers. At the tissue level, we discuss genomic alterations and mutational signatures, transcriptomic classification systems and immune-related gene expression tools, protein-level immune checkpoint markers, and cellular determinants including immune infiltrates, cancer-associated fibroblasts and microbiome features. At the circulating level, we review biomarkers derived from liquid biopsy and peripheral blood, including circulating tumor DNA kinetics, T-cell receptor repertoire diversity, soluble cytokines and proteins, immune cell phenotyping, and circulating tumor cells. We highlight major challenges limiting clinical translation, including tumor heterogeneity, methodological variability, and the absence of standardized analytical pipelines and thresholds. Finally, we discuss future perspectives, emphasizing the integration of multi-omics biomarkers and artificial intelligence-driven strategies to improve biomarker validation and enable more precise management of metastatic colorectal cancer, particularly for patients with microsatellite-stable tumors who derive limited benefit from immune checkpoint inhibition. Full article

Historically, mpox was thought to be a geographically constrained ‘disease of poverty,’ leading to decades of neglect by global health actors. Waning population immunity from the cessation of smallpox vaccination and prolonged scientific neglect created conditions that enabled the monkeypox virus (MPXV) to adapt cryptically. This ultimately contributed to the emergence of unprecedented global public health crises. This review aims to systematically trace the history, epidemiology, genomic evolution, and reservoir ecology of mpox in West Africa from 1970 to 2025. Following PRISMA guidelines, 110 articles met the inclusion criteria and were synthesized to map the virus’s trajectory. For nearly four decades, an “Era of Silence” (1970–2016) masked the silent enzootic circulation of MPXV within West African wildlife, primarily rodents and small mammals. This epidemiological quiescence ended with the 2017 re-emergence in Nigeria, which signaled a fundamental paradigm shift. The disease profile transitioned from sporadic, rural paediatric infections to sustained, urban and secondary transmission among young adult males. This shift was often associated with sexual networks, especially among men who have sex with men, and was characterized by novel clinical presentations, including genital and perianal lesions. Genomic analyses revealed that clade II diverged from clade I approximately 3500 years ago and is uniquely defined by the deletion of virulence factors, such as the complement-binding protein. Importantly, the clade IIb lineage, which triggered the 2022 global outbreak, exhibits accelerated microevolution consistent with APOBEC3-mediated hypermutation. This host-driven mutational signature provides genomic evidence supporting the hypothesis that clade IIb circulated cryptically within human-to-human transmission chains in West Africa as early as 2014. Ecologically, while no definitive reservoir has yet been identified, evidence suggests diverse rodents and an expanding host range. The transformation of mpox from a rare zoonosis to a global threat underscores the severe consequences of delayed intervention, demanding robust, integrated “One Health” surveillance. Full article

Fusobacterium nucleatum has been implicated in colorectal cancer, but its role in adenomas remains unclear. We applied an RNA-based detection of F. nucleatum in formalin-fixed paraffin-embedded adenoma tissue and explored the mutational landscape and transcriptomic profile of F. nucleatum+ patients in comparison to F. nucleatum- patients. Bespoke F. nucleatum probes successfully detected F. nucleatum in 11% of adenomas. F. nucleatum+ patients exhibited a positively enriched anti-bacterial defence response and immune-related transcriptomic signatures, as well as a proliferative profile. These findings suggest that F. nucleatum positivity is associated with immune and proliferative transcriptomic signatures in colorectal adenomas, but this requires validation in larger, longitudinal cohorts. Full article

Background/Objectives: African swine fever (ASF) has caused substantial wild boar (Sus scrofa) mortality across Europe and prompted intensive density-reduction measures, yet its long-term effects on population genetics remain poorly understood. To our knowledge, this is the first study to compare genetic diversity, population structure, demographic signatures, and wildlife forensic identification parameters in the same wild boar population before ASF emergence and after several years of ASF-related management. Methods: Wild boar samples collected before ASF emergence in Hungary (n = 67) were compared with samples collected after several years of ASF-related management from the same geographic area (n = 65). All 132 individuals were genotyped at 13 tetrameric microsatellite loci. Diversity was assessed using allelic richness, allele number, and heterozygosity; differentiation using F-statistics, analysis of molecular variance, and discriminant analysis of principal components; demographic history using a two-phase mutation model; and forensic performance using probability of identity and probability of identity among siblings. Results: The post-ASF population showed lower genetic diversity and significant temporal differentiation. Paired Wilcoxon tests indicated a significant reduction in the number of alleles, whereas changes in heterozygosity were not significant. Bottleneck analyses provided no robust evidence of a recent genetic bottleneck. Forensic discrimination power declined modestly while remaining sufficient for individual identification. Conclusions: Because no contemporaneous unaffected reference population was available, these changes cannot be attributed specifically to ASF or management rather than to genetic drift or natural turnover, although they are consistent with sustained demographic disturbance. Nevertheless, this study provides the first temporal genetic comparison of a European wild boar population before ASF emergence and after several years of ASF-related management and demonstrates that a routinely used STR marker panel remains suitable for wildlife forensic individual identification despite these genetic changes. Full article

Cutaneous melanoma and basal cell carcinoma (BCC) represent the two primary malignancies driven by solar ultraviolet (UV) radiation. To map the spatial topology and distance dependence of their mutational signatures, we deployed new analytical bioinformatics workflow utilizing two convergent strategies: a data-driven read-level phasing framework to discriminate between collateral mutational events versus independent ones and a hypothesis-driven spatial permutational simulation model to capture density-dependent local deviations. A whole-genome analysis employing this framework unexpectedly reveals two fundamentally distinct lesion-processing landscapes, present in both BCC and melanoma. While independent mutations consistently reproduce canonical UV signatures (SBS7a–c) in both tumor types, collateral mutations tell a distinct and more varied narrative between BCC and melanoma. These collateral mutations are unusually abundant for non-UV characteristics, such as age-related SBS1 and SBS5, and display a notable 3′ to 5′ asymmetry near UV-induced lesions in pyrimidine dimers. We also demonstrated that BCC displays a pronounced enrichment of dinucleotide base substitutions flanking UV-signature sites on the 3′ side, particularly CA>TG and CG>TA changes. Ultimately, these topological patterns in both tumors indicate that a primary photoproduct seeds secondary mutagenesis within its local chromatin environment, dramatically altering our understanding of UV-induced lesion processing. Full article