Isofetamid is a succinate dehydrogenase inhibitor (SDHI) fungicide used to combat gray mold. As a single-site fungicide, it inhibits cellular respiration and offers a novel chemical solution for managing strawberry gray mold in Shanghai. This research evaluated the response of 260 Botrytis cinerea populations to isofetamid collected from strawberry orchards across various districts of Shanghai (2019 to 2023), examined SdhB gene mutations linked to resistance, and studied cross-resistance relationships among four SDHIs: boscalid, isofetamid, fluopyram, and fluxapyroxad. The results demonstrated that the EC50 values of 183 isolates for isofetamid ranged from 0.001 to 0.33 μg/ml, with a mean value of 0.16 ± 0.01 μg/ml. The frequency distribution of these EC50 values exhibited a unimodal curve, suggesting it can be considered as the baseline sensitivity. From 2019 to 2023, a significant upward trend in resistance frequency to isofetamid was observed. Four distinct SdhB mutations were detected: H272Y/R, N230I, and P225F, at frequencies of 5.38, 26.15, 20.0, and 9.62%, respectively. H272Y isolates showed the highest susceptibility to isofetamid and fluopyram but were either resistant (R) or highly resistant (HR) to fluxapyroxad and boscalid. The N230I and P225F mutations resulted in R or HR to all tested SDHIs. Additionally, the cross-resistance analysis indicated that mutations conferring resistance to fluopyram also reduced isofetamid efficacy, while mutations conferring resistance to boscalid similarly compromised fluxapyroxad activity against B. cinerea. These results suggest that isofetamid is a highly effective fungicide against B. cinerea in Shanghai, but a significant increase in resistance frequencies occurred year by year. Consequently, adopting strategic fungicide rotations will reduce future selection pressure on existing SDHI-resistant isolates.

Succinate dehydrogenase inhibitor (SDHI) fungicides are used to manage Stemphylium leaf blight (SLB) of onion caused by the fungus Stemphylium vesicarium. The SDHIs commonly used for SLB management in New York (NY) onion production are boscalid (first registered in 2005), fluxapyroxad (2015), fluopyram (2016), and pydiflumetofen (2019). However, reduced field performance of these products across multiple onion-producing regions within NY has been encountered. We quantified the in vitro sensitivity of S. vesicarium isolates collected from five onion-producing regions throughout NY in 2016, 2018, and 2020. To evaluate whether variations in in vitro sensitivity phenotypes were associated with target-site mutations, sequencing of the sdhB, sdhC, and sdhD genes associated with fungicide response was conducted. We identified a shift in sensitivity over a short period, that is, although more than 90% of isolates sampled in 2016 were sensitive to fluopyram and fluxapyroxad (EC50 < 1 mg/liter), more than 50% of isolates sampled in 2018 exhibited reduced sensitivity (EC50 > 1 mg/liter). This change in fungicide sensitivity was observed in three of the four main onion-producing regions of NY and emphasizes the need for improved disease management practices to preserve their efficacy. Primers were developed to sequence the full sdh genes of 176 isolates from all regions and years sampled. Thirteen single-nucleotide polymorphisms were identified in the sdhB, sdhC, and sdhD genes, and 11 were found to predict nonsynonymous amino acid (aa) substitutions. The isolates with genotypes P230H (SDHB) and G79R, H134N/R, and C135R (SDHC) were associated with the reduced sensitivity of S. vesicarium to fluopyram and fluxapyroxad. These putative aa substitutions were not associated with effects on mycelial growth at one temperature. Spatiotemporal analyses revealed a clear shift in population structure from wild-type populations in 2016 to diverse genotypes with multiple substitutions across onion-producing regions by 2020. The rapid, diverse, and widespread distribution of genotypes with putative aa substitutions suggests an ongoing adaptation and the presence of strong selective forces in S. vesicarium in NY.

Objective. To evaluate the role of molecular genetic testing in patients with pheochromocytomas and paragangliomas, to determine genotype-phenotype correlations and their impact on clinical characteristics, imaging approaches, and prognosis. Materials and methods. The prospective study included 14 patients hospitalized at the O. O. Shalimov National Scientific Center for Surgery and Transplantology of the National Academy of Medical Sciences of Ukraine in 2018–2025. All patients underwent genetic testing using next-generation sequencing with confirmation of mutations by the Sanger method, biochemical examination (liquid chromatography–tandem mass spectrometry for metanephrines, normetanephrines, 3-methoxytyramine), morphological and immunohistochemical studies. Computed tomography and magnetic resonance imaging were performed, as well as functional imaging (positron emission tomography/computed tomography using the radiopharmaceuticals DOTA-SSA and FDOPA). Descriptive and comparative statistics were used for statistical analysis. Results. Pathogenic or likely pathogenic gene mutations were detected in 12 (85.7%) of 14 patients. The most common were SDHB gene mutations (64.3%), associated with a noradrenergic or "biochemically silent" phenotype and a high risk of metastasis (21.4%). Patients with VHL and RET (MEN2A) gene mutations had characteristic multifocality and bilateral tumors. Functional imaging revealed genotype-specific patterns: positron emission tomography/computed tomography with DOTA-SSA demonstrated high sensitivity in SDHB-associated tumors (over 90%), while FDOPA was optimal for VHL- and RET/NF1-associated tumors. The disease debuted earliest in patients with SDHB-associated tumors (median age 32 years), and its clinical manifestations differed depending on the genotype. Conclusions. Molecular genetic testing is critically important for risk stratification and personalized management of patients with pheochromocytomas/paragangliomas. Identification of genotype-phenotype correlations enables disease prognosis, informed choice of functional imaging method, planning of screening for first-degree relatives , and determination of therapeutic strategy, including theranostic approaches.

Abstract Background: Breast cancer is the most common non-cutaneous malignancy among women, with around 10% of cases involving germline mutations in DNA repair genes. Germline mutations in BRCA1/2 genes significantly increase breast cancer risk. Other relevant genes to increase the risk of breast cancer include TP53, PTEN, PALB2, CHEK2, and ATM. Multigene panel testing can sequence many genes, sometimes identifying non-disease-related genes and variants of unknown significance. Methods: We reviewed patients with newly diagnosed breast cancer diagnosis from 2022 to 2024 in our institution. Germline genetic testing was offered to all newly diagnosed breast cancer patients at the time of diagnosis irrespective of their family history. Testing was offered to patients with invasive breast cancer and ductal carcinoma in situ. The goal of this study was to identify the prevalence of genes not attributed to increasing the risk of breast cancer and the implications of those results. Results: A total of 478 patients (Invasive cancer and DCIS) were seen in our oncology clinic from January 2022 to December 2024. The median age at diagnosis was 66 years (range 28-91). Invasive ductal cancer (IDC) was the most common subtype (66%), followed by DCIS (18%). Most patients had estrogen-positive cancer (81%), and approximately 14% had HER2-positive disease (62% HER2 low). We found 27 patients with pathogenic germline mutations which are not related to breast cancer risk. The most common mutation was MUYTH (7 patients), followed by FH gene (3 patients). MSH3, LZTR1, and HOXB13 genes were each found in 2 patients. APC, BAP1, BLM, BRIP1, NTHL1, SDHA, SDHB, MSH6, MITF, and FLCN genes were each identified in one patient. All patients with MUYTH mutations had hormone-positive (HER 2 negative) disease contrary to the limited observation of triple-negative breast cancer related to the MUYTH gene in the available literature. Patients with positive mutations were offered genetic counseling and referred to a high-risk genetics' clinic. FANCM was observed in one patient which has rarely been associated with an increased risk of triple-negative breast cancer. Conclusion: We present our single institution's experience of germline mutations in breast cancer patients. Previously, we observed CHEK2 being the most common breast cancer-related germline mutation in our patient population. This analysis focuses on identifying germline mutations without an increased risk of breast cancer. MUTYH was the most common pathogenic mutation identified. Further studies are needed to determine the actual risk percentage of breast cancer associated with the MUTYH gene. Universal testing for all breast cancer patients is feasible with the lower cost of multi-gene panels. However, identifying other non-disease-related genes, as observed in our study, has implications. Patients must be informed about the consequences of a positive result, including genetic counseling, additional screening tests, and testing of immediate family members. Citation Format: M. Zafar, M. Krishnakumar, A. Reddy. Non-breast cancer related germline mutations in breast cancer patients: a single institution experience [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS3-05-18.

Acromegaly and gigantism are rare neuroendocrine diseases caused by excessive secretion of growth hormone (GH) and/ or high levels of insulin-like growth factor (IGF-1). Gigantism develops when excess GH or IGF-1 leads to accelerated linear growth before the completion of puberty and the closure of the epiphyses, most commonly caused by a somatotropic pituitary adenoma. The diagnosis of somatotropinoma in childhood is particularly challenging due to its subtle and nonspecific clinical presentation. Somatotropinomas at a young age are more often caused by genetic abnormalities and have a more aggressive course. The article presents a clinical case of acrogigantism in a patient with two identified heterozygous variants in the PRKAR1A and SDHB genes. The scientific interest of the described observation is due to the debut of gigantism in childhood, complex pathogenetic treatment, as well as the experience of using the growth hormone receptor antagonist pegvisomant in a teenager in Russia.

Background: Pheochromocytomas (PCCs) and paragangliomas (PGLs), collectively known as PPGLs, are rare neuroendocrine tumors that produce catecholamines. The majority of PPGL cases are caused by germline and/or somatic mutations in over 20 different genes. A study of post-surgical PCC patients revealed a high risk of new tumor recurrence in both hereditary and apparently sporadic cases, suggesting that some germline mutations remain undetected. Since transcript levels can indicate gene dysfunction, our study focuses on the transcriptional profiling of PCC-associated genes in post-surgical patients. Methods: RT-PCR was performed on blood samples from patients and a control group. The t-SNE algorithm was applied to the transcriptional data. Sanger sequencing was used to identify mutations in the coding sequences of the VHL, SDHB, RET, and NF1 genes. Results: We obtained transcriptional profiles for 11 genes involved in the Krebs cycle and for 21 genes involved in the hypoxia, PI3K/AKT/mTOR, and RAS/RAF/ERK signaling pathways. We identified a minimal set of 16 genes with stable transcription levels that can be used to differentiate PCC patients from controls. Germline mutations in the VHL, SDHB, RET and NF1 genes, which correlated with an altered transcriptional profile, were detected in three patients. Conclusions: Our pilot data suggest that transcript levels of the genes involved in Krebs cycle, hypoxia, PI3K/AKT/mTOR, and RAS/RAF/ERK signaling pathways indicate their potential suitability as a candidate diagnostic marker. The results from this pilot study form the basis for a larger project to investigate gene transcription in an expanded cohort of patients who have undergone surgery for PCC.

Mutations in sdhB and sdhC genes confer different cross-resistance patterns to SDHI fungicides in isolates of Passalora nattrassii, causal agent of leaf mold in eggplant, and high efficacy of pyribencarb against cytb-mutant isolates

Background and aimVitamin B12 deficiency remains a major cause of nutritional anemia in children, particularly in low- and middle-income countries. While intramuscular (IM) vitamin B12 is the traditional treatment, the sublingual route offers a simpler, painless alternative with potentially comparable efficacy. Thus, this study was planned to compare the efficacy of sublingual versus IM vitamin B12 supplementation in children with confirmed vitamin B12 deficiency anemia.Materials and methodsA prospective comparative study was conducted among children aged 1-15 years at a tertiary care center in Uttar Pradesh. Participants were randomized by using a computer-generated table into two groups: Group A received IM vitamin B12, and Group B received sublingual vitamin B12 for 12 weeks. Blinding of study subjects or the investigating officer was not possible due to obvious differences in the routes of administration of the drugs (IM vs. sublingual). However, the outcome assessors, including the laboratory personnel and the statistician, were blinded to avoid bias. The allocation concealment was performed using the sequentially numbered, opaque, sealed envelopes (SNOSE) method to minimize selection bias by the investigating officer. Hematological parameters, such as hemoglobin (Hb), mean corpuscular volume, total leucocyte count, platelet count, and serum B12, were evaluated at baseline, one month, and three months. Our primary outcome measures were correction of anemia beyond WHO age-specific thresholds and correction of B12 levels to >300 pg/mL as per the Indian Academy of Pediatrics guidelines.ResultsA total of 73 patients (Group A: 36 and Group B: 37) with comparable baseline clinical and hematological characteristics participated in the study. The baseline mean ± SD Hb levels were 8.33 ± 1.14 g/dL in Group A and 8.46 ± 1.24 g/dL in Group B, while the mean ± SD B12 levels were 132.53 ± 38.33 pg/mL and 141.20 ± 31.65 pg/mL in Groups A and B, respectively. The mean ± SD Hb levels at three months were 12.07 ± 0.78 g/dL and 12.31 ± 0.73 g/dL in Group A and Group B, respectively, showing a significant increase from baseline, although the results were comparable across both groups. Statistically significant increments of serum B12 levels (Group A: 329.30 ± 34.94 pg/mL; Group B: 337.08 ± 44.19 pg/mL) were also noted. Normalization of B12 levels was achieved in 100%, while a nonanemic status was achieved in 80.8% (59/73) of the participants. Both routes were well tolerated, and no adverse events were noted during the study period.ConclusionsSublingual vitamin B12 is as effective as IM administration for pediatric B12 deficiency anemia. Although the parenteral route remains the gold standard in cases with neurological involvement or severe thrombocytopenia, the sublingual route may be considered for maintenance therapy, as it is a noninvasive, child-friendly alternative that also offers a distinct cost benefit. Therefore, the sublingual route may be considered a potential option, pending evidence from larger, multicenter trials with longer follow-up periods.

The widespread emergence of fungicide-resistant Botrytis cinerea populations, together with increasingly strict regulatory constraints, has intensified the need for alternative and environmentally sustainable strategies for gray mold management. This study evaluates spray-induced gene silencing (SIGS) targeting mitochondrial respiration through double-stranded RNAs (dsRNAs) directed against sdhB and cytB genes. These genes encode key subunits of respiratory complexes II and III, key targets and determinants of resistance to SDHI and QoI fungicides, respectively. Exogenous application of these dsRNAs significantly reduced B. cinerea conidial germination (~50%), lesion development in tomato leaves and apple fruits (~45%), fungal biomass (~50%), and transcript levels of sdhB (3.2-fold) and cytB (2.0-fold). When combined with sublethal doses of boscalid (SDHI) or azoxystrobin (QoI), dsRNA treatments markedly decreased lesion severity in fungicide-sensitive isolates, achieving substantial but not full equivalent to field-dose fungicide efficacy. In resistant isolates, dsRNA alone consistently reduced disease symptoms, and its combination with sublethal-dose fungicides further enhanced control. When dsRNA was applied together with full-rate fungicide, lesion development declined sharply across all resistant isolates, and in some cases gray mold symptoms were completely eradicated, indicating the strong biological effect achieved by the RNAi-fungicide combination. Sequence identity analyses revealed strong cross-species activity among closely related Botrytis and Sclerotiniaceae species, with no predicted effects on unrelated fungi, plants, or humans. This work provides the first demonstration of a dual-target SIGS strategy acting on mitochondrial respiration, highlighting its potential as a precise, eco-compatible, and effective tool for managing B. cinerea resistance within integrated pest management frameworks.

Aim To determine if antibiotic tolerance impairs prophylactic antibiotics against Methicillin Resistant Staphylococcus aureus (MRSA) in orthopedic surgery Method We evaluated MRSA strains for resistance to vancomycin and ceftobiprole, using broth microdilution (BMD). We evaluated antibiotic tolerance using the Tolerance Disk Test (TD-test). Whole genome sequencing was used to identify mutations underlying tolerance. Tolerant and non-tolerant strains were subjected to a mouse prosthetic joint infection (PJI) model following a single dose of vancomycin given 60 minutes prior to surgery and infection. Bacterial load was evaluated by in vivo bioluminescent imaging for 30 days and by ex vivo enumeration of tissue bacterial colony forming units (CFUs) after completion of the experiment. Tolerance was further compared between wild type, mutant and deletion strains using TD-test and kill curve analysis in normal and low oxygen tension (normoxia and hypoxia, respectively). Results We tested 17 osteogenic MRSA strains of which none were resistant to vancomycin. Two strains, however, were highly tolerant to vancomycin (Figure 1A-B). Whole genome sequencing revealed a mutation in the sdhB gene, which is part of the succinate dehydrogenase (SDH) enzyme complex and essential for energy production and respiration. In a mouse prosthetic joint infection model, the mutant ( sdhB N51S ) led to a ~100-fold higher bacterial load post-antibiotic treatment compared to wild-type (p=0.0286; Figure 1C-E). Deletion of sdhB significantly reduced antibiotic tolerance for both vancomycin and ceftobiprole (Figure 1F-H). Hypoxia increased antibiotic tolerance in wild-type and sdhB N51S mutant strain but did not impact the D sdhB deletion strain (Figure 1I-K). Conclusions A mutation in sdhB , a key regulator of metabolism and energy production in S. aureus , is associated with hypoxia-driven antibiotic tolerance and reduces the efficacy of prophylactic antibiotics. Interestingly, deletion of the gene renders the bacteria highly susceptible to antibiotics, highlighting this mechanism as a potential therapeutic target. For any figures or tables, please contact the authors directly.

Disclosure: H. Marasandra Ramesh: None. A. Paudel: None. F. Manas: None. J. Pamula: None.Introduction: Pheochromocytoma is a tumor arising from adrenal medullary chromaffin cells. Most patients with pheochromocytoma have disease-causing germline mutations and they present at a younger age. Here we present a case of recurrent metastatic pheochromocytoma in a young patient with a loss of SDHB gene in the tumor. Case Presentation: A 25-year-old female with a history of migraine and hypertension was incidentally found to have a 3.5 cm left adrenal nodule. She had long term symptoms of headaches, nausea, dizziness, vision changes, night sweats and palpitations and history of multiple emergency visits for hypertensive emergencies. Lab work showed elevated plasma free total metanephrines (1825 pg/ml, normal < 205 pg/ml) and 24-hour urine total metanephrines (6334 ug/day, normal 140-785 ug/day). Ga-68 Dotatate scan showed increased radiotracer uptake in left adrenal mass. Hereditary paraganglioma- pheochromocytoma panel (including sequencing and deletion/duplication analysis of MAX, NF1, RET, SDHA,SDHAf2, SDHB, SDHC, SDHD, TMEM127, and VHL genes) was negative. She underwent robotic left adrenalectomy. Pathology was consistent with composite pheochromocytoma (pheochromocytoma and ganglioneuroma), 6.5 cm in size, with focal areas of necrosis, extension into margins and extra-adrenal adipose tissue and lymphovascular invasion. SDHB immunostaining revealed loss of SDHB in the tumor. She presented again 3 years later with recurrence of headaches, vision changes, anxiety, night sweats and palpitations. Lab work again showed elevated plasma free total metanephrines (3307 pg/mL, normal < 205 pg/ml) and 24-hour urine total metanephrines (5109 ug/day, normal 140-785 ug/day). CT findings were consistent with recurrent pheochromocytoma adjacent to pancreatic tail, with new metastatic disease involving multiple para-aortic lymph nodes, the right lobe of the liver and skeletal metastasis involving the sacrum and left sixth rib. NM MIBG scan showed no abnormal accumulation, but Ga-68 Dotatate scan showed increased radiotracer uptake in left adrenal mass. She underwent distal pancreatectomy, hepatic wedge resection, splenectomy, and lymphadenectomy and is currently undergoing chemotherapy. Discussion: Malignant pheochromocytoma is diagnosed when there is evidence of metastases at non-chromaffin sites distant from the primary tumor such as lymph nodes, bones, liver, lung, or brain. Larger tumor size (≥5 cm) and young age at diagnosis are predictors of increased risk of malignancy. Usually, about 10 % of pheochromocytomas are malignant but mutations of SDHB gene lead to metastatic disease in 40% or more of affected patients. There are no specific systemic treatment guidelines for metastatic pheochromocytoma however, debulking surgery, chemotherapy, radionuclide therapy, tyrosine kinase inhibitors and immunotherapy are some of the standards of therapy.Presentation: Saturday, July 12, 2025

Disclosure: S. Lee: None. L. Needleman: None. J. Park: None. R. Schugar: None. J.P. Annes: None.Pathogenic mutations in the succinate dehydrogenase complex, particularly in the SDHB gene, predispose individuals to hereditary pheochromocytoma and paraganglioma (hPPGL). However, more than 80% of missense SDHB variants are classified as variants of uncertain significance (VUS) in ClinVar. Consequently, numerous families harboring an SDHB VUS are at elevated oncologic risk, but do not benefit from early detection protocols. As SDHB pathogenicity is caused by impaired SDH enzymatic activity, functional evaluation may help resolve VUS classification. Hence, we developed a functional biochemical assay using CRISPR/Cas9-engineered SDHB-knockout HEK293 cells to assess succinate/fumarate ratios by LC-MS/MS as a proxy for SDH enzymatic activity. Loss of SDHB led to a marked elevation in the succinate/fumarate ratio, which was restored by transfection of wild-type SDHB. Expression of 35 classified variants (9 benign, 26 pathogenic) clustered into low and high succinate/fumarate ratio groups, validating the assay’s ability to resolve SDHB variant functionality. To improve interpretability, we converted succinate/fumarate ratios into SDH % activity, which was used for the logistic regression modeling of known variants. Using the trained model, P(path) and OddsPath values were calculated to assign ACMG/AMP functional evidence strength (BS3/PS3). Compared to the computational predictor REVEL, our assay provided superior discrimination between benign and pathogenic variants. This model was applied to 33 VUSs, including 16 Stanford patient alleles and three causative of Leigh syndrome. Twenty-three VUSs demonstrated wild-type-like activity (BS3), while 10 exhibited marked SDH dysfunction and were assigned PS3strong. Following ACMG/AMP guidelines, mock clinical interpretation that included our functional assay recategorized 78% of SDHB VUSs (16 likely benign and 10 likely pathogenic). Notably, all SDHB VUSs affecting highly conserved cysteine residues responsible for Fe-S cluster coordination showed complete enzymatic loss, confirming the critical function of these domains. Interestingly, recessive mitochondrial disease-associated SDHB variants (Leighs) were not reliably distinguished from wild-type-like variants, indicating these variants are not causative for hPPGL. Finally, pathogenic variants with relatively lower succinate/fumarate ratios than PPGL-predominant variants were associated with increased occurrence of head and neck paragangliomas (HNPGL; r2=0.45; p=0.0001). Logistic modeling identified a metabolic threshold predictive of tumor location; hence, SDH dysfunction severity influences location-specific tumor risk. Together, these data establish a robust, quantitative platform for SDHB variant classification with immediate clinical implications for risk assessment and tumor surveillance.Presentation: Saturday, July 12, 2025

Disclosure: O. Onwudiwe: None. A.M. Aviles Melendez: None. R. Zafar: None.Background: Pheochromocytoma is a rare neuroendocrine tumor originating from chromaffin cells in the adrenal glands. Most cases are benign and may be unilateral or bilateral, with an incidence of 0.29 to 0.66 cases per 100,000 person-years. Symptoms include paroxysmal attacks of headaches, sweating, palpitations, and hypertension, although some cases, like the one described here, can be asymptomatic. Case: A 64-year-old woman, a former smoker with no significant history, was referred to the endocrine clinic for an incidental left adrenal mass identified during lung cancer screening. CT and MRI confirmed a 4 cm left adrenal mass. She was asymptomatic, with a family history notable for breast and lung cancer in her sister and prostate cancer in her father. Biochemical evaluation revealed elevated plasma and urine metanephrines and normetanephrines. Dopamine, renin, and aldosterone were negative. Following alpha and beta blockade, she underwent a left adrenalectomy. Pathology confirmed pheochromocytoma, with tumor cells staining positive for synaptophysin, chromogranin, GATA-3, and focal staining for S-100 and SOX-10. SDHB immunohistochemical staining showed retained expression. She recovered well and remained asymptomatic at her one-month follow-up. Discussion: Pheochromocytoma, though rare, can present asymptomatically, as in this case. Risk factors include genetic and non-genetic contributors. A significant proportion is linked to inherited syndromes, such as MEN2A, MEN2B, NF1, and VHL. Germline mutations in RET, VHL, NF1, SDHB, and other genes are also associated with pheochromocytomas and paragangliomas. Even asymptomatic pheochromocytomas require treatment due to the risk of hypertensive crises and severe cardiovascular complications, including myocardial infarction, pulmonary edema, stroke, and Tako-Tsubo cardiomyopathy. Excessive catecholamine secretion can precipitate multi-organ failure or a pheochromocytoma crisis, characterized by hyperthermia, encephalopathy, and labile blood pressure. Without treatment, pheochromocytomas can metastasize, leading to poor prognosis and significantly increased mortality. Historical data show that up to 50% of cases were identified post-mortem due to fatal cardiovascular events. Conclusion: Untreated pheochromocytoma poses risks of fatal cardiovascular events, multi-organ failure, and metastasis, all contributing to increased mortality. Current guidelines strongly advocate for treating all pheochromocytomas, regardless of symptoms, to prevent these potentially life-threatening outcomes.Presentation: Saturday, July 12, 2025

Sarcopenia and obesity, two prevalent metabolic disorders in aging populations, often coexist and share overlapping pathophysiological mechanisms, yet the molecular mechanisms underlying their comorbidity remain elusive. This study aimed to identify key gene expression signatures and pathways underlying their comorbidity through integrative transcriptomic and bioinformatics analyses. Gene expression datasets from sarcopenia (GSE111016, skeletal muscle) and obesity (GSE152991, adipose tissue) were downloaded from the GEO database. Differentially expressed genes (DEGs) were identified using the limma package, and 208 common differentially expressed genes (CDEGs) were selected via Venn diagram intersection. Functional enrichment analyses (GO and KEGG) were performed to explore shared biological processes and pathways. A protein-protein interaction (PPI) network was constructed using STRING and Cytoscape, and key CDEGs were identified via ten topological algorithms (e.g., MCC, Degree) in the CycloHubba plugin. Pearson correlation analysis and qPCR were used to validate gene co-expression patterns and expression levels in tissue samples. GO and KEGG analyses revealed that CDEGs were significantly enriched in mitochondrial oxidative phosphorylation, electron transport chain, and thermogenesis pathways, with overlap in neurodegenerative disease pathways. The PPI network and multi-algorithm integration identified four key CDEGs: SDHB, SDHD, ATP5F1A, and ATP5F1B, all of which are components of mitochondrial respiratory chain complexes. These genes exhibited strong positive correlations (r > 0.86, p < 10⁻¹²) in both datasets and were significantly downregulated in sarcopenia and obesity tissues, as validated by qPCR. This study confirms mitochondrial dysfunction, particularly impaired oxidative phosphorylation, as a common pathological mechanism linking sarcopenia and obesity. The key genes SDHB, SDHD, ATP5F1A, and ATP5F1B represent potential therapeutic targets for managing these comorbid metabolic disorders. Future research should explore their functional roles in energy metabolism and cross-tissue crosstalk to develop targeted interventions.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-18824-y.

A total of 442 non-synonymous SNPs (nsSNPs) in the SDHB gene were screened using four predictive tools: SIFT, AlignGVGD, PANTHER, and MutPred. Four high-risk variants (H132P, R177C, R217C, and R230C) were consistently predicted to be deleterious across all tools. Among them, the R217C variant was prioritized for detailed downstream analysis due to its high oncogenic scores and significant structural disruptions. Conservation profiling indicated these variants occurred at highly conserved and solvent-accessible residues. Molecular dynamics simulation revealed the R217C mutant exhibits increased rigidity, altered radius of gyration, reduced flexibility, and constrained principal motions, suggesting functional damagein mitochondrial Complex II. MuTarget analysis revealed that SDHB has limited transcriptional impact as a genotype but is significantly modulated by upstream mutations in cancers such as colon adenocarcinoma, sarcoma, and ovarian cancer. Survival analysis using TCGA datasets showed a trend toward poorer disease-free survival in sarcoma and lower overall survival in SDHB-mutated stomach adenocarcinoma and PCPG cases. Together, these results highlight the pathogenic potential of specific SDHB nsSNPs, particularly R217C, and support their relevance in cancer development and prognosis.

Fenopyramid is a new succinate dehydrogenase inhibitor (SDHI), which will be soon launched on the market. Sensitivity detection and resistance risk assessment should be performed promptly to track the emergence of fenopyramid resistance and establish resistance management strategies. In this study, the sensitivity of 78 R. solani isolates to fenopyramid was evaluated, along with resistance risk, cross-resistance patterns, fitness costs, and resistance mechanisms in the lab. Three low-level resistant mutants and three high-level resistant mutants were obtained by repeated exposures of wild-type sensitive isolates to fenopyramid. The fitness in mycelial growth, mycelial biomass, and pathogenicity of the low-level resistant mutants were less than or similar to that of the parental isolate. There was no fitness cost in the high-level resistant mutants in comparison with that of the parental isolate. Fenopyramid had moderate to strong cross-resistance with commonly used SDHIs thifluzamide, boscalid, carboxin, flubeneteram, and non-SDHIs fluazinam. Overall, the results suggest that the resistance risk of R. solani to fenopyramid is moderate. Mixtures of fenopyramid with four DMIs showed synergistic effects. Therefore, it is recommended to mix fenopyramid with DMIs in a proper mass ratio to avoid and delay the development of fenopyramid-resistance. No mutations or significant expression changes were detected in the target-site genes SDHA, SDHB, SDHC, and SDHD. Other nontarget-related resistance mechanism may be responsible and require further investigation.

Glomus tumors, also known as paragangliomas, were previously classified as benign tumors; however, the WHO classification of endocrine and neuroendocrine tumors 4th edition no longer classified paragangliomas as benign and malignant given any lesion can have metastatic potential. Temporal bone glomus tumors are classified into glomus tympanicum tumors and glomus jugulare tumors. Complete surgical resection is preferred for glomus tympanicum tumors whereas, for glomus jugulare tumors, it is necessary to evaluate age, tumor extension, hearing, and neurological symptoms to determine treatment strategy. In cases of catecholamine production, cranial nerve paralysis, young age, and SDHB gene mutations, surgery should be considered. The infratemporal fossa type A approach is one of the main surgical approaches for glomus jugulare tumors. Management of glomus jugulare tumors requires a thorough understanding of pathophysiology of the tumor including biochemistry, genetics, and metastasis. Surgery, radiotherapy, and active surveillance are treatment options, and should be individualized to patients to maintain quality of life.

Family matters! - a rare case of SDHB gene linked metastatic paraganglioma

The RS0 cell line is a rat-derived pheochromocytoma line developed as a model to study pheochromocytoma/paraganglioma caused by hereditary mutations of the SDHB gene. Previous studies demonstrated that xenografts of the RS0 parent tumor replicate characteristics of their human counterparts, including loss of SDHB and upregulation of genes in hypoxia signaling pathways activated by EPAS1/HIF2A. Establishment of the cell line required a low O2 concentration, as cell proliferation was arrested in a traditional cell culture atmosphere of 20% O2. The present study profiled the effects of 20% versus 5% O2 and EPAS1/HIF2A inhibitors on the RS0 cell phenotype and tested how RS0 cells cultured under these influences compare to their parent xenografts and normal rat adrenal medulla. O2 concentration in cell cultures influences almost every aspect of the cells' biology, most obviously proliferation but also ultrastructure, transcriptome, metabolism and endocrine function. The cells most closely resemble their xenografts when maintained in a low O2 environment, but some differences between the cells in vivo and in vitro are not fully explained. Genes downregulated in high O2 are predominantly associated with the cell cycle, while those upregulated in low O2 include stemness and neuronal progenitor markers that may have contributed to the establishment of the cell line, as well as drug targets expressed in human pheochromocytoma/paraganglioma. Some effects of high O2 are mimicked by EPAS1/HIF2A inhibitors currently considered for treatment of metastatic Sdh-deficient PPGL, while others may be HIF-independent. The cytostatic effect of EPAS1/HIF2A inhibitors is reversible, suggesting possible limits to their usefulness as monotherapies.

The piggyBac+TET-on transposon induction system has a high efficiency in integrating exogenous genes in multiple cell types, can precisely integrate to reduce genomic damage, has a flexible gene expression regulation, and a strong genetic stability. When used in conjunction with somatic cell nuclear transfer experiments, it can precisely and effectively reveal the intrinsic mechanisms of early biological development. This study successfully reprogrammed black-boned sheep fibroblasts (SFs) into induced pluripotent stem cells (iPSCs) using the piggyBac+TET-on transposon system and investigated their impact on early embryonic development. Seven exogenous reprogramming factors (bovine OCT4, SOX2, KLF4, cMyc, porcine NANOG, Lin-28, and SV40 Large T) were delivered into SFs, successfully inducing iPSCs. A growth performance analysis revealed that iPSC clones exhibited a raised or flat morphology with clear edges, positive alkaline phosphatase staining, and normal karyotypes. The transcriptome analysis indicated a significant enrichment of iPSCs in oxidative phosphorylation and cell proliferation pathways, with an up-regulated expression of the ATP5B, SDHB, Bcl-2, CDK1, and Cyclin D1 genes and a down-regulated expression of BAX (p < 0.05). Somatic cell nuclear transfer experiments demonstrated that the cleavage rate (85% ± 2.12) and blastocyst rate (52% ± 2.11) of the iPSCs were significantly higher than those of the SFs (p < 0.05). The detection of trilineage marker genes confirmed that the expression levels of endoderm (DCN, NANOS3, FOXA2, FOXD3, SOX17), mesoderm (KDR, CD34, NFH), and ectoderm (NEUROD) markers in iPSCs were significantly higher than in SFs (p < 0.01). The findings demonstrate that black-boned sheep iPSCs possess pluripotency and the potential to differentiate into all three germ layers, revealing the mechanisms by which reprogrammed iPSCs influence early embryonic development and providing a critical foundation for research on sheep pluripotent stem cells.