Predicting somatic mutation origins in cell-free DNA by semi-supervised GAN models.

Motivation: Distinguishing between pathogenic cancer-associated mutations and other somatic variants present in cell-free DNA (cfDNA) is one of the challenges in the field of liquid biopsy. This distinction is critical, since the misclassification of mutations stemming from clonal hematopoiesis (CH) as tumor-derived and vice versa could result in inaccurate diagnoses and inappropriate therapeutic interventions for patients. Results: We addressed this by developing a specialized machine learning technique to differentiate tumor- or CH-related mutations in cfDNA. We established a comprehensive in-house reference catalog, comprising approximately 25,000 single nucleotide variants (SNVs), each linked to either tumor or CH origin. This reference serves as a foundation for training a deep learning model, which is structured on the semi-supervised generative adversarial network (SSGAN) architecture. By analyzing genomic coordinates and nucleotide composition of cfDNA variants, our model attains 95 % area under the curve (AUC) in classifying uncharacterized variants as CH or tumor-derived. In conclusion, our research emphasizes the potential of genomic feature prediction, using cfDNA data, to stand as a robust alternative to conventional multi-analyte sequencing methods. This approach not only enhances the accuracy of distinguishing CH from tumor mutations in liquid biopsy data, but also highlights the potential of advanced data analysis techniques and machine learning in genomics and personalized medicine. Availability: https://github.com/FPalizban/SSGAN.

Double Hit in Clear-Cell Renal Cell Carcinoma With Germline Pathogenic ATM Mutation and Somatic VHL Mutation.

While renal cell carcinoma (RCC) is often linked to smoking, obesity, and hypertension, hereditary forms also account for about 3% of RCC cases. Notably, NCCN guidelines identify 7 major hereditary syndromes associated with an increased RCC risk. Inherited mutations in DNA repair genes, such as ATM, BRCA, and TP53, significantly increase the risk of various cancers. Biallelic pathogenic mutations in ATM cause Ataxia-Telangiectasia (A-T) syndrome, while heterozygous germline pathogenic ATM mutations, present in about 1% of the population, also elevate cancer risk. RCC has not traditionally been associated with germline pathogenic ATM mutations, only limited retrospective analyses have identified such mutations. This case report presents a 68-year-old woman with a germline pathogenic ATM mutation (c.8786+1 G>A) who developed high-risk clear cell RCC followed by an acquired somatic VHL mutation in RCC and a 3-cm serous cystadenoma, illustrating the double-hit phenomenon. Her brother, who shares the same germline pathogenic mutation, was diagnosed with pancreatic cancer and prostate cancer. This case highlights the potential use for enhanced screening protocols for RCC in patients who have germline pathogenic ATM mutations and the importance of research in targeted treatments for tumors driven by dual genetic mechanisms. Increased awareness and vigilant screening for RCC are crucial in managing hereditary cancer syndromes effectively.

Somatic gene mutations involved in DNA damage response/Fanconi anemia signaling are tissue- and cell-type specific in human solid tumors.

With significant advancements in the study of DNA Damage Response (DDR) and Fanconi Anemia (FA) signaling, we previously introduced the term "FA signaling" to encompass "all signaling transductions involving one or more FA proteins." This network has now evolved into the largest cellular defense network, integrating over 30 key players, including ATM, ATR, BLM, HRR6, RAD18, FANCA, FANCB, FANCC, BRCA2, FANCD2, FANCE, FANCF, FANCG, FANCI, BRIP1, FANCL, FANCM, PALB2, RAD51C, SLX4, ERCC4, RAD51, BRCA1, UBE2T, XRCC2, MAD2L2, RFWD3, FAAP20, FAAP24, FAAP100, and CENPX. This system responds to both endogenous and exogenous cellular insults. However, the mutational signatures associated with this defense mechanism in non-FA human cancers have not been extensively explored. In this study, we report that different types of human cancers are characterized by distinct somatically mutated genes related to DDR/FA signaling, each accompanied by a unique spectrum of potential driver mutations. For example, in pan-cancer samples, ATM emerges as the most frequently mutated gene (5%) among the 31 genes analyzed, with the highest number of potential driver mutations (1714), followed by BRCA2 (4% with 970 putative driver mutations). However, this pattern is not universal across specific cancer types. For example, FANCT is the most frequently mutated gene in breast (14%) and liver (4%) cancers. In addition, the alteration frequency of DDR/FA signaling due to these mutations exceeds 70% in a subtype of prostate cancer, with each subtype of brain, breast, lung, and prostate cancers displaying distinct patterns of gene alteration frequency. Furthermore, these gene alteration patterns significantly impact patient survival and disease-free periods. Collectively, our findings not only enhance our understanding of cancer development and progression but also have significant implications for cancer patient care and prognosis, particularly in the development of effective therapeutic strategies.

Preliminary identification of somatic mutations profile in ACL injury.

Anterior cruciate ligament (ACL) injury is a common orthopedic disease with a high incidence, long recovery time, and often requiring surgical treatment. However, the susceptibility factors for ACL injury are currently unclear, and there is a lack of analysis on the differences in the ligament itself. Previous studies have focused on germline mutations, with less research on somatic mutations. To determine the role of somatic mutations in ACL injuries, we recruited seven patients between the ages of 20 and 39 years diagnosed with ACL injuries, collected their peripheral blood, injured ligament ends, and healthy ligament ends tissues, and performed exome sequencing with gene function enrichment analysis. We detected multiple gene mutations and gene deletions, which were only present in some of the samples. Unfortunately, it was not possible to determine whether these somatic mutations are related to ligament structure or function, or are involved in ACL injury. However, this study provides valuable clues for future in-depth research.

Vasculitis associated with VEXAS syndrome.

OBJECTIVES: To define the prevalence, distribution, and characteristics of patients with VEXAS who have confirmed vasculitis. METHODS: Patients with VEXAS syndrome, verified by positive UBA1 mutation, were included. Chart review was performed to identify. PATIENT: characteristics and outcomes. Vasculitis diagnosis was based on either histopathology showing vascular inflammation or non-invasive angiography findings. Summary statistics were calculated. RESULTS: Eighty-nine patients met inclusion criteria. All were male with a median age of onset of 66.9 years (IQR 60.1, 72.7). Median (IQR) follow up was 3.8(2.2-5.5) years during which 21 patients (23.6%) had evidence of vasculitis. Vasculitis subtypes included small vessel vasculitis (19.1%), cutaneous medium vessel vasculitis (2.2%), and large vessel vasculitis (2.2%). No patient had more than one vessel size involved. Histopathology in small vessel vasculitis patients was consistent with cutaneous leukocytoclastic vasculitis in the majority, though one patient had leukocytoclastic peritubular capillaritis on renal biopsy. Cranial symptoms (headache, vision changes, or jaw pain) were noted in 18.0%. Two additional patients not experiencing cranial symptoms exhibited large vessel involvement with confirmed carotid thickening on non-invasive angiography; one of these had a positive temporal artery biopsy. CONCLUSION: VEXAS syndrome manifests as a variable vessel vasculitis in a quarter of patients, with cutaneous small and medium vessel involvement being particularly common. Some patients may have positive ANCA serologies or even renal vasculitis leading to misdiagnosis. Cranial symptoms are common and may mimic giant cell arteritis, though documented large vessel inflammation is rare.

Non-Hotspot PIK3CA Variants Have Higher Variant Allele Frequency and are More Common in Syndromic Vascular Malformations.

PIK3CA variants are known to cause vascular malformations. We were interested in studying the phenotypic spectrum, the location within the PIK3CA gene, and the variant allele frequency (VAF) of somatic PI3KCA variants in vascular malformations. Clinical data of consecutive patients with extracranial/extraspinal vascular malformations were collected in the context of the VASCOM cohort (2008-2022, n = 558). Starting October 2020, biopsy samples were tested with the TSO500 gene panel (Illumina). All consenting patients with PIK3CA variants were included in this study. Eighty-nine patients had available genetic results by June 2022. PIK3CA variants (n = 25) were found in 16 simple/combined (nonsyndromic) vascular malformations and in nine vascular malformations associated with other anomalies (syndromic). Four hotspot variants in exons 9 and 20 (c.1624G>A, c.1633G>A, c.3140A>G, c.3140A>T) were identified in 16/25 patients (VAF 0.9%-9.7%). Six non-hotspot variants (c.328_330del, c.323_337del, c.353G>A, c.1258T>C, c.3132T>A, c.3195_3203delinsT) were detected in nine patients (VAF 3.6%-31.7%). Non-hotspot variants were more frequent in syndromic than nonsyndromic vascular malformations (p = 0.0034) and exhibited a higher VAF than hotspot variants (p = 0.0253). Our study contributes to the growing body of knowledge of the genetic background in vascular malformations. Further studies will enrich the ever-growing list of pathogenic PIK3CA variants associated with vascular malformations.

Exploring the Relationship Between Gene Expression and Low-Frequency Somatic Mutations in Arabidopsis with Duplex Sequencing.

Intragenomic mutation rates can vary dramatically due to transcription-associated mutagenesis or transcription-coupled repair, which vary based on local epigenomic modifications that are nonuniformly distributed across genomes. One feature associated with decreased mutation is higher expression level, which depends on environmental cues. To understand the magnitude of expression-dependent mutation rate variation, we perturbed expression through a heat treatment in Arabidopsis thaliana. We quantified gene expression to identify differentially expressed genes, which we then targeted for mutation detection using duplex sequencing. This approach provided a highly accurate measurement of the frequency of rare somatic mutations in vegetative plant tissues, which has been a recent source of uncertainty. Somatic mutations in plants may be useful for understanding drivers of DNA damage and repair in the germline since plants experience late germline segregation and both somatic and germline cells share common repair machinery. We included mutant lines lacking mismatch repair (MMR) and base excision repair (BER) capabilities to understand how repair mechanisms may drive biased mutation accumulation. We found wild-type (WT) and BER mutant mutation frequencies to be very low (mean variant frequency 1.8 × 10-8 and 2.6 × 10-8, respectively), while MMR mutant frequencies were significantly elevated (1.13 × 10-6). Interestingly, in the MMR mutant lines, there was no difference in the somatic mutation frequencies between temperature treatments or between highly versus lowly expressed genes. The extremely low somatic variant frequencies in WT plants indicate that larger datasets will be needed to address fundamental evolutionary questions about whether environmental change leads to gene-specific changes in mutation rate.

Somatic mutation rates scale with time not growth rate in long-lived tropical trees.

The rates of appearance of new mutations play a central role in evolution. However, mutational processes in natural environments and their relationship with growth rates are largely unknown, particular in tropical ecosystems with high biodiversity. Here, we examined the somatic mutation landscapes of two tropical trees, Shorea laevis (slow-growing) and S. leprosula (fast-growing), in central Borneo, Indonesia. Using newly constructed genomes, we identified a greater number of somatic mutations in tropical trees than in temperate trees. In both species, we observed a linear increase in the number of somatic mutations with physical distance between branches. However, we found that the rate of somatic mutation accumulation per meter of growth was 3.7-fold higher in S. laevis than in S. leprosula. This difference in the somatic mutation rate was scaled with the slower growth rate of S. laevis compared to S. leprosula, resulting in a constant somatic mutation rate per year between the two species. We also found that somatic mutations are neutral within an individual, but those mutations transmitted to the next generation are subject to purifying selection. These findings suggest that somatic mutations accumulate with absolute time and older trees have a greater contribution towards generating genetic variation.

FBXW7 as a Factor of the African American and White Breast Cancer Racial Disparity.

INTRODUCTION: African American women have a breast cancer mortality rate 40% higher than Caucasian women. Many contributing factors account for this racial disparity, such as socioeconomic status and the age when women give birth, but even after considering such factors, studies have found that the racial disparity persists, suggesting that genetic factors may play a crucial role in this breast cancer racial inequality. METHODS: This study utilizes the All of Us database, The Cancer Genome Atlas (TCGA), and an array of bioinformatics tools to integrate differential mutation and gene expression analyses, aiming to identify genes potentially associated with this racial disparity. Although previous studies have identified genes associated with this breast cancer racial disparity through mutation or gene expression analysis, no studies have considered both simultaneously. Ultimately, this study considers both mutation and gene expression to discover novel genes linked to this racial disparity. RESULTS: After mutation analysis, this study identified FBXW7, a gene involved in the destruction of oncogenic proteins, as being associated with this racial inequality. FBXW7  was the only gene that presented differences in both mutation frequency and gene expression between African Americans and Caucasians. The other four candidate genes, such as COL12A1, whose upregulation plays a critical role in tumor progression, may also be linked to this racial inequality. CONCLUSION: By combining both mutation and gene expression analysis, this research offers a unique perspective into this issue. Furthermore, the identification of FBXW7 provides insight into this racial disparity, which can contribute to the pursuit of more effective or personalized treatment for both Caucasian and African American breast cancer patients. Finally, the multi-level method presented could possibly apply to other racial disparities, providing a distinctive perspective that cannot be found with other methods.

Effect of C-to-T transition at CpG sites on tumor suppressor genes in tumor development in cattle evaluated by somatic mutation analysis in enzootic bovine leukosis.

Oncogenic transformation of normal cells is caused by mutations and chromosomal abnormalities in cancer-related genes. Enzootic bovine leukosis (EBL) is a malignant B-cell lymphoma caused by bovine leukemia virus (BLV) infection in cattle. Although a small fraction of BLV-infected cattle develops EBL after a long latent period, the mechanisms for oncogenesis in EBL cattle remain largely unknown. In this study, we analyzed the types and patterns of somatic mutations in cancer cells from 36 EBL cases, targeting 21 cancer-related genes. Various somatic mutations were identified in eight genes, TP53, KMT2D, CREBBP, KRAS, PTEN, NOTCH1, MYD88, and CARD11. In addition, TP53 gene was found to be mutated in 69.4% of EBL cases, with most being biallelic mutations. In some cases, associations were observed between the ages at which cattle had developed EBL and somatic mutation patterns; young onset of EBL possibly occurs due to high impact mutations affecting protein translation and biallelic mutations. Furthermore, nucleotide substitution patterns indicated that cytosine at CpG sites tended to be converted to thymine in many EBL cases, which was considered to be the result of spontaneous deamination of 5-methylcytosine. These results demonstrate how somatic mutations have occurred in cancer cells leading to EBL development, thereby explaining its pathogenic mechanism. These findings will contribute to a better understanding and future elucidation of disease progression in BLV infection.IMPORTANCEEnzootic bovine leukosis (EBL) is a malignant and lethal disease in cattle. Currently, there are no effective vaccines or therapeutic methods against bovine leukemia virus (BLV) infection, resulting in severe economic losses in livestock industry. This study provides a renewed hypothesis to explain the general mechanisms of EBL onset by combining the previous finding that several integration sites of BLV provirus can affect the increase in survival and proliferation of infected cells. We demonstrate that two additional random events are necessary for oncogenic transformation in infected cell clones, elucidating the reason why only few infected cattle develop EBL. Further exploration of somatic mutation and BLV integration sites could support this hypothesis more firmly, potentially contributing to the development of novel control methods for EBL onset.

Low remission rates and high incidence of adverse events in a prospective VEXAS syndrome registry.

OBJECTIVE: We aimed to gather real-world clinical evidence of detailed disease activity, treatments, remission rates, and adverse events (AEs) associated with vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome in a prospective study. METHODS: Patients in Japan suspected of having VEXAS syndrome were enrolled in a registry study. A novel disease activity measure (VEXASCAF) assessing 11 symptoms associated with VEXAS syndrome was evaluated at enrolment and after 3 months. AEs, survival, CRP levels, and treatments were also recorded at enrolment and 3 months after enrolment. All exons of UBA1 were sequenced using a next-generation sequencer to determine the variant allele frequencies of pathogenic variants in the peripheral blood of all patients. RESULTS: Of the 55 registered patients, 30 patients were confirmed to have pathogenic variants of UBA1. All patients were male, with a median age of 73.5 years. VEXASCAF and CRP levels decreased significantly at 3 months post-enrolment, but the oral prednisolone dose did not change. Only two patients achieved complete remission according to FRENVEX at 3 months after enrolment. During the observation period of 6 months, 28 AEs were observed, including 3 deaths, 4 malignancies from two cases, 2 thromboses, and 13 infections (including 4 mycobacterial infections). Inflammation of the lung and cervical region (i.e. parotid and submandibular gland swelling, tonsillitis, cervical swelling, and pain) were the most common AEs. CONCLUSIONS: Patients with VEXAS syndrome required high-dose glucocorticoids to achieve remission, and complications-such as malignancy, thrombosis, and infection-occurred frequently within a short observation period.

FAT4 Mutation is Related to Tumor Mutation Burden and Favorable Prognosis in Gastric Cancer.

Objective: This study aimed to investigate the frequently mutated genes in Gastric Cancer (GC), assess their association with Tumor Mutation Burden (TMB) and the patients' survival, and identify the potential biomarkers for tailored therapy. Methods: Simple somatic mutation data of GC were collected from the TCGA and ICGC databases. The high-frequency mutated genes were identified from both datasets. The samples were initially dichotomized into wild-type and mutation groups based on the status of overlapping genes. TMB difference between the two groups was evaluated by the Mann-Whitney U-test. Survival difference between the two groups was compared by the Kaplan-Meier method with a log-rank test. The prognostic value of the target gene was assessed by the Cox proportional hazards model. The signaling pathways involved in FAT4 mutation were identified by Gene Set Enrichment Analysis (GSEA). The fractions of different tumor-infiltrating immune cells were calculated by the CIBERSORT algorithm. Results: 21 overlapping genes with frequent mutation were identified in both datasets. Mutation of these genes was significantly associated with higher TMB (P<0.05) in GC. The survival of the FAT4 mutation group was superior to the wild-type group. FAT4 mutation was also identified as an independent favorable prognostic factor for the GC patients. GSEA indicated that FAT4 mutation activated the signaling pathways involved in energy metabolism. Finally, CD4 memory-activated T cells, follicular helper T cells, and gamma delta T cells were significantly more enriched, while naïve B cells and regulatory T cells (Tregs) were significantly less enriched in the FAT4 mutation group (P<0.05). Conclusion: FAT4 mutation is relevant to TMB and favorable prognosis in GC, which may become a useful biomarker for immunotherapy of GC patients.

Next generation sequence-based targeted somatic mutation analysis in thyroid nodules with pathologically diagnosed as indeterminate cytology.

PURPOSE: The management of indeterminate thyroid nodules remains a topic of ongoing debate, particularly regarding the differentiation of malignancy. Somatic mutation analysis offers crucial insights into tumor characteristics. This study aimed to assist the clinical management of indeterminate nodules with somatic mutation analysis. METHODS: Aspiration samples from 20 indeterminate thyroid nodules were included in the study. A next-generation sequencing panel containing 67 genes was used for molecular profiling. The results were compared with pathology data from surgical material, which is considered the gold standard. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. RESULTS: Variants in six genes (NRAS, BRAF, TP53, TERT, PTEN, PIK3CA) were detected in 10 out of 20 samples. We identified nine Tier 1 or 2 variants in 10 (67 %) out of 15 malignant nodules (NRAS, BRAF, TP53, TERT, PTEN, PIK3CA) and one Tier 2 (PIK3CA) variant in one out of five benign nodules. The study demonstrated an NPV of 40 %, a PPV of 90 %, a specificity of 80 %, and a sensitivity of 60 %. CONCLUSION: Based on the detected molecular markers, at least nine patients (45 %) could be managed correctly without needing a repeat FNAB attempt. This study underscores the clinical practicality of molecular tests in managing nodules with indeterminate cytology. Additionally, this study emphasizes the importance of considering the patient's age when determining the DNA- or RNA-based genetic testing method. Finally, we discussed the significance of the somatic mutation profile and its impact on the current pathological classification.

Whole exome sequencing in relapsed or refractory childhood cancer: case series.

Background: The prognosis for relapsed or refractory childhood cancer is approximately 20%. Genetic alterations are one of the significant contributing factors to the prognosis of patients. Objective: To investigate the molecular profile of relapsed or refractory childhood cancers in Thai cases. Methods: The study design is a descriptive study of patients <18 years old, suspected or diagnosed of relapsed or refractory childhood cancer who underwent whole exome sequencing (WES). Results: WES was successfully performed in both the tumor and the blood or saliva samples obtained from 4 unrelated patients. Six different variants were identified in the NCOR2, COL6A3, TP53, and SMAD4 genes. These alterations were found to be associated with tumor aggressiveness. Conclusion: This study is the first one to demonstrate genetic alterations by using WES in relapsed or refractory childhood cancer in Thai cases.

Mitochondrial DNA copy number associated dementia risk by somatic mutations and frailty.

Mitochondrial dysfunction is linked to physical impairment and dementia. Mitochondrial DNA copy number (mtDNAcn) from blood may predict cognitive decline and dementia risk, but the effect of somatic mutations or frailty is unknown. We estimated mtDNAcn using fastMitoCalc and microheteroplasmies using mitoCaller, from Whole Genome Sequencing (WGS) data. In 189,566 participants free of dementia at study entry (mean age = 56 ± 8), we examined the association between mtDNAcn and subsequent dementia diagnosis using Cox regression. Cognition was assessed in a subset on average 8.9 years later. We examined the associations between mtDNAcn and cognitive measures using multivariable linear regression, adjusted for demographic factors, mtDNAcn-related parameters, and apolipoprotein E ε4 status. We further stratified by frailty and microheteroplasmies. Over an average follow-up of 13.2 years, 3533 participants developed dementia. Each SD higher mtDNAcn (16) was associated with 4.2% lower all-cause dementia hazard (HR = 0.958, p = 0.030), 6% lower non-AD dementia hazard (HR = 0.933, p = 0.022), and not-AD dementia hazard. The associations between mtDNAcn and all-cause dementia and non-AD dementia were stronger among those who were pre-frail or frail or with higher microheteroplasmies. Higher mtDNAcn was associated with higher DSST scores (p = 0.036) and significant only among those with higher microheteroplasmies or frailty (p = 0.029 and 0.048, respectively). mtDNAcn was also associated with delta TMT and paired associate learning only in pre-frail/frail participants (p = 0.007 and 0.045, respectively). Higher WGS-based mtDNAcn in human blood is associated with lower dementia risk, specifically non-AD dementia, and specific cognitive function. The relationships appear stronger in high somatic mutations or frailty. Future studies are warranted to investigate biological underpinnings.

Somatic mutations in arteriovenous malformations in hereditary hemorrhagic telangiectasia support a bi-allelic two-hit mutation mechanism of pathogenesis.

Hereditary hemorrhagic telangiectasia (HHT) is an inherited disorder of vascular malformations characterized by mucocutaneous telangiectases and arteriovenous malformations (AVMs) in internal organs. HHT is caused by inheritance of a loss of function mutation in one of three genes. Although individuals with HHT are haploinsufficient for one of these genes throughout their entire body, rather than exhibiting a systemic vascular phenotype, vascular malformations occur as focal lesions in discrete anatomic locations. The inconsistency between genotype and phenotype has provoked debate over whether haploinsufficiency or a different mechanism gives rise to the vascular malformations. We previously showed that HHT-associated skin telangiectases develop by a two-hit mutation mechanism in an HHT gene. However, somatic mutations were identified in only half of the telangiectases, raising the question whether a second-hit somatic mutation is a necessary (required) event in HHT pathogenesis. Here, we show that another mechanism for the second hit is loss of heterozygosity across the chromosome bearing the germline mutation. Secondly, we investigate the two-hit mutation mechanism for internal organ AVMs, the source of much of the morbidity of HHT. Here, we identified somatic molecular genetic events in eight liver telangiectases, including point mutations and a loss of heterozygosity event. We also identified somatic mutations in one pulmonary AVM and two brain AVMs, confirming that mucocutaneous and internal organ vascular malformations undergo the same molecular mechanisms. Together, these data argue that bi-allelic loss of function in an HHT gene is a required event in the pathogenesis of HHT-associated vascular malformations.

Functional landscape of genome-wide postzygotic somatic mutations between monozygotic twins.

Monozygotic (MZ) twins originate from a single fertilized egg, making them genetically identical at the time of conception. However, postzygotic somatic mutations (PZMs) can introduce genetic differences after separation. Although whole-genome sequencing (WGS) sheds light on somatic mutations in cancer genomics, its application in genomic studies of MZ twins remains limited. In this study, we investigate PZMs in 30 healthy MZ twin pairs from the Osaka University Center for Twin Research using WGS (average depth = 23.8) and a robust germline-calling algorithm. We find high genotype concordance rates (exceeding 99%) in MZ twins. We observe an enrichment of PZMs with variant allele frequency around 0.5 in twins with highly concordant genotypes. These PZMs accumulate more frequently in non-coding regions compared with protein-coding regions, which could potentially influence gene expression. No significant association is observed between the number of PZMs and age or sex. Direct sequencing confirms a missense mutation in the ANKRD35 gene among the PZMs. By applying a genome-wide mutational signature pattern technique, we detect an age-related clock-like signature in these early postzygotic somatic mutations in MZ twins. Our study provides insights that contribute to a deeper understanding of genetic variation in MZ twins.

Molecular Genetics of Pheochromocytoma/Paraganglioma.

Pheochromocytomas and paragangliomas (PPGL) are neuroendocrine tumors which secrete catecholamines, causing cardiovascular compromise. While isolated tumors and locoregional disease can be treated surgically, treatment options for metastatic disease are limited, and no targeted therapies exist. Approximately 25% of PPGL are causatively associated with germline pathogenic variants, which are known risk factors for multifocal and metastatic PPGL. Knowledge of somatic driver mutations continues to evolve. Molecular classification of PPGL has identified three genomic subtypes: Cluster 1 (pseudohypoxia), Cluster 2 (kinase signaling) and Cluster 3 (Wnt-altered). This review summaries recent studies characterizing the tumor microenvironment, genomic drivers of tumorigenesis and progression, and current research on molecular targets for novel diagnostic and therapeutic strategies in PPGL.

Allogenic haematopoietic stem cell transplantation in VEXAS: A review of 33 patients.

Vacuolation, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome is a multisystem disease due to a genetic mutation in the ubiquitin-activating enzyme (UBA1). Allogeneic haematopoietic stem cell transplantation (allo-HSCT) offers both therapeutic and cure but also carries significant risks. A review of VEXAS and HSCT cases was undertaken. Thirty-three patients were identified; majority males (n = 32, 97.0%), median time from symptoms to HSCT: 3 years (IQR 2.0-4.8) and median age of 59 years (IQR 52.5-65.5). UBA1 mutation Met41Thr was most common (11/32, 34.4%). The median variant allele frequency was 56.5% (IQR 43.0-73.5) with no correlation with increasing age. Prior to HSCT, 4.5 (IQR 2.8-6) treatments were trialled. Peripheral blood HSCT (30/31, 96.8%) and HLA-matched, unrelated donor (18/32, 56.3%) were most common. Conditioning regimens varied, with reduced intensity treatment with fludarabine as a co-agent most frequently administered (12/31, 38.7%). Both acute and/or chronic GVHD (18/32, 56.3%) and infections were common (12/32, 37.5%). Overall, 27 individuals (81.8%) were alive, and those undergoing HSCT prospectively had median follow up of 9 months (IQR 3.8-14.4). Of the six deceased, infection was implicated in four. In 11 cases with post-HSCT molecular data, a complete eradication of UBA1 mutation was reported. In summary, while consensus treatment strategy regarding VEXAS is lacking, this review highlights HSCT may remain not only a therapeutic option but also enable cure. However, considerations regarding comorbidities, concurrent haematological disorders as well as overall risks of GVHD and infections need to be made. Key points • Very few reported prospective cases of VEXAS and allogeneic haematopoietic stem cell transplantation (allo-HSCT) have been reported. • While risks of graft versus host disease and infection remain barriers, this treatment modality remains an option for selected patients. • Allo-HSCT is the only treatment strategy which can remove the UBA1 mutation.

Somatic mutations in tumor-infiltrating lymphocytes impact on antitumor immunity.

Immune checkpoint inhibitors (ICIs) exert clinical efficacy against various types of cancers by reinvigorating exhausted CD8+ T cells that can expand and directly attack cancer cells (cancer-specific T cells) among tumor-infiltrating lymphocytes (TILs). Although some reports have identified somatic mutations in TILs, their effect on antitumor immunity remains unclear. In this study, we successfully established 18 cancer-specific T cell clones, which have an exhaustion phenotype, from the TILs of four patients with melanoma. We conducted whole-genome sequencing for these T cell clones and identified various somatic mutations in them with high clonality. Among the somatic mutations, an SH2D2A loss-of-function frameshift mutation and TNFAIP3 deletion could activate T cell effector functions in vitro. Furthermore, we generated CD8+ T cell-specific Tnfaip3 knockout mice and showed that Tnfaip3 function loss in CD8+ T cell increased antitumor immunity, leading to remarkable response to PD-1 blockade in vivo. In addition, we analyzed bulk CD3+ T cells from TILs in additional 12 patients and identified an SH2D2A mutation in one patient through amplicon sequencing. These findings suggest that somatic mutations in TILs can affect antitumor immunity and suggest unique biomarkers and therapeutic targets.