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In-Season Assessment of Dietary Intake and Match Demands of Men's Collegiate Rugby Sevens Players
Horlock, Conor F., Allen, Leah E. , Jones, Margaret T., Fields, Jennifer B., Jagim, Andrew R.

Mayo Clinic

Journal of Strength & Conditioning Research | June 1, 2026 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.1519/jsc.0000000000005473 | PMID 42223156 Get It

Abstract Horlock, CF, Allen, LE, Jagim, AR, Jones, MT, and Fields, JB. In-season assessment of dietary intake and match demands of men’s collegiate Rugby Sevens players. J Strength Cond Res XX(X): 000–000, 2026—Limited research has examined the external workload demands and dietary intake of collegiate men's Rugby Sevens players. Therefore, the purpose of this study was to (a) quantify match demands in Division 1-AA collegiate Rugby Sevens across a competitive season, and (b) assess players' dietary intake relative to sport-specific nutrition guidelines. Division 1-AA men's collegiate Rugby Sevens players ( n = 13; age: mass: 87 ± 14 kg; body fat %: 20 ± 4%) wore a global positional system device during all matches ( n = 17). External load metrics were total distance (TD) (m), sprint distance (>20.1 km·h −1 ), high-intensity distance (>18.1–20.0 km·h −1 ), meters per minute (m·min −1 ), acceleration efforts (#), deceleration efforts (#), sprint efforts (#), high-speed efforts (#), player load (PL) (arbitrary unit [AU]), PL per minute (AU/min), and estimated energy expenditure (EE) (kcal). Dietary intake was assessed at the start of the season using a 4-day food log. Linear mixed models examined changes in workload parameters across tournament matches. Spearman's rank correlation and linear regression assessed relationships and predictability of EE and external workloads. One-samples t test compared dietary intake relative to established guidelines ( p ≤ 0.05). No significant differences in workload metrics were observed across individual matches. Total distance ( r = 0.968, p < 0.001), m·min −1 ( r = 0.973, p < 0.001), PL ( r = 0.912, p < 0.001), and PL/min ( r = 0.855, p < 0.001) had the strongest correlations with EE. Players significantly underconsumed calories ( p = 0.028) and carbohydrates ( p < 0.01). Monitoring external workloads and assessing dietary intake can provide coaches with strategies to optimize sports performance and nutrition support to prepare players for competition demands.
Pemigatinib for Unresectable or Metastatic Cholangiocarcinoma With Fibroblast Growth Factor Receptor–2 Rearrangement: Results From the Phase III FIGHT-302 Trial
Bekaii‐Saab, Tanios , Wilmink, Hanneke , Garufi, Carlo , Tran, Nguyen H. , Tortora, Giampaolo , Braud, Filippo de, Lonardi, Sara , Lin, E., Babiker, Hani, Lin, Bruce, Martín, Andrés Muñoz, Bridgewater, J, Knox, J J, Scott-Brown, Martin , Veronese, Luisa, Ioannidis, Sonia, Gilmartin, Aidan, Janik, John E., Guo, Yufei, Furuse, Junji , Ioka, Tatsuya , Rimassa, Lorenza , Braud, Filippo de , Bekaii-Saab, Tanios S , Melisi, Davide , Tran, Nguyen , Tortora, Giampaolo , De Braud, Filippo , Lonardi, Sara , Babiker, Hani , Fornaro, Lorenzo , Muñoz Martín, Andrés , Bridgewater, John , Knox, Jennifer J , De Vos-Geelen, Judith , Scott-Brown, Martin , Furuse, Junji , Rimassa, Lorenza , Vogel, Arndt , Frödin, Jan‐Erik , Lin, Bruce, Fornaro, Lorenzo , Knox, Jennifer J. , Veronese, Maria Luisa, Gilmartin, Aidan G., Janik, John E.

Mayo Clinic

Journal of Clinical Oncology | June 1, 2026 | Volume: 44 | Issue: 23 | Pages: 2187-2197

10.1200/jco-26-00788 | PMID 42223137 Get It

PURPOSE Cholangiocarcinoma is a rare cancer associated with poor prognosis. Pemigatinib was the first FGFR1-3 inhibitor approved for second-line therapy and beyond, on the basis of the phase II FIGHT-202 trial. Here, we assess efficacy and safety of first-line pemigatinib. METHODS FIGHT-302 is a phase III, randomized, global trial evaluating pemigatinib as first-line therapy (ClinicalTrials.gov identifier: NCT03656536 ). Adults with advanced cholangiocarcinoma with FGFR2 rearrangement were randomized 1:1 to receive pemigatinib (13.5 mg once daily) or chemotherapy (1,000 mg/m 2 gemcitabine plus 25 mg/m 2 cisplatin once per day on days 1 and 8 of every 3-week cycle for ≤8 cycles) and were stratified by prior receipt of chemotherapy, geographic region, and tumor burden. Pemigatinib crossover was allowed for patients progressing on chemotherapy. The primary end point was progression-free survival (PFS). Secondary efficacy, safety, and exploratory end points were also analyzed. RESULTS Overall, 4,563 patients were prescreened, 196 were screened, and 167 randomly assigned to receive pemigatinib (n = 83) or chemotherapy (n = 84) before early closure of the study because of a change in standard of care. The median PFS was 8.3 months in the pemigatinib group versus 6.8 months in the chemotherapy group (hazard ratio, 0.58 [95% CI, 0.39 to 0.87]; nominal P = .0078); objective response rate was 47% versus 15%, and the median duration of response was 14.2 versus 6.3 months. Median overall survival was similar (24.4 v 25.0 months, respectively). In the crossover group (n = 42, second-line pemigatinib), the median PFS was 8.1 months. Safety was consistent with the known profile of pemigatinib. CONCLUSION To our knowledge, this was the largest, first-line, randomized, phase III trial of a targeted therapy for advanced FGFR2- rearranged cholangiocarcinoma. Pemigatinib demonstrated prolonged median PFS compared with chemotherapy, with no new safety findings.
Indications and Outcomes of Non-Emergent Cardiac Surgery Following Transcatheter Aortic Valve Replacement
Schaff, Hartzell V, Greason, Kevin L. , Bagameri, Gabor, Dearani, Joseph A, Holst, Kimberly , Pochettino, Alberto, Arghami, Arman , Todd, Austin, Crestanello, Juan A, Schaff, Hartzell V. , Qamar, Younus , Schaff, Hartzell , Holst, Kimberly A, Pochettino, Alberto , Arghami, Arman , Dearani, Joseph A. , Pochettino, Alberto , Todd, Austin , Crestanello, Juan A.

Mayo Clinic

Interdisciplinary CardioVascular and Thoracic Surgery | June 1, 2026 | Volume: 41 | Issue: 7 | Pages: No page available

10.1093/icvts/ivag142 | PMID 42231119 Get It

Abstract Objectives This study examined the indications, frequency, and outcomes of cardiac surgery following transcatheter aortic valve replacement (TAVR) at a single institution. As TAVR volumes increase, understanding the nature and outcomes of subsequent cardiac operations is critical, particularly as the procedure expands to younger, lower-risk populations. Methods We analysed outcomes of 61 patients who underwent cardiac surgery after TAVR at our institution from August 2011 to September 2023, excluding periprocedural complications and staged procedures. Patients were stratified into 2 groups: those requiring surgical aortic valve replacement (SAVR) with or without concomitant procedures (n = 33) and those undergoing non-SAVR cardiac operations (n = 28). Data were collected from a prospectively maintained cardiovascular surgery database and electronic health records. Indications for surgery, operative characteristics, and outcomes were analysed, with survival assessed using Kaplan-Meier estimates. Results The median interval between TAVR and cardiac surgery was 19 months. Indications for SAVR included infective endocarditis (36%), non-structural valve deterioration (36%), structural valve deterioration (12%), and valve thrombosis (6%). Non-SAVR operations primarily addressed mitral valve disease (43%) and coronary artery disease (29%). Operative mortality was 6.6%, with no deaths in the endocarditis subgroup. Postoperative complications included prolonged mechanical ventilation (18%), new-onset renal failure (7%), and stroke (2%). Kaplan-Meier survival estimates were 83% at 1 year and 50% at 5 years. Conclusions Although complex, cardiac operations in patients who have undergone TAVR can be performed with acceptable mortality rates. Structural valve deterioration, paravalvular leak, and endocarditis were the primary indications for SAVR, while mitral valve and coronary artery disease predominated in non-SAVR cases. These findings highlight the importance of considering nonaortic valve pathologies in TAVR planning, particularly as the procedure expands to younger, lower-risk populations.
The impact of global recruitment and country income on placebo rates in inflammatory bowel disease clinical trials
Goodwin, Shane W. , Yuan, Yuhong , Singh, Siddharth, Solitano, Virginia , Bose, Rishabh , Shehab, Mohammad , Narula, Neeraj , Ma, Christopher, Ahuja, Vineet , Ahuja, Vineet , Narula, Neeraj , Jairath, V , Solitano, Virginia , Singh, S , Vuyyuru, Sudheer K. , Jairath, Vipul , Ahuja, Vineet

Mayo Clinic

Journal of Crohn's and Colitis | June 1, 2026 | Volume: 20 | Issue: 6 | Pages: No page available

10.1093/ecco-jcc/jjag081 | PMID 42357952 Get It

Abstract Introduction Despite progress in understanding placebo effects in clinical trials of inflammatory bowel disease (IBD), there is a limited understanding of how socioeconomic factors of recruiting countries impact placebo rates. We investigated the association of socioeconomic factors across recruitment sites on placebo rates in IBD randomized controlled trials. Methods We examined the association of clinical and endoscopic remission and response to the weighted Gross National Index (GNI) per capita, Human Development Index (HDI), and out-of-pocket health expenditures as a percentage of current health expenditures (OOP_CHE) of identified trials using mixed effects linear regression. Results Across 76 trials (Crohn’s disease [CD]: n = 32; ulcerative colitis [UC]: n = 44), placebo response rates over time were largely stable, with a small increase across time in clinical remission for CD trials (β = 0.4% per increase in study year, 95% CI: 0.3%-0.84%, P = .04) and a small decrease across time in endoscopic response for UC trials (β = −1.39% per increase in study year, 95% CI: −1.79, −0.99, P &lt; .001). Clinical response was most susceptible to changes in socioeconomic factors in IBD trials (β = −2.96% per 10 000 USD increase in study GNI, 95% CI: −4.98, −0.95%, P = .004; P &lt; .05 for HDI and OOP_CHE). Across both conditions, decreases in clinical response were associated with increases in HDI and OOP_CHE (CD HDI: β = −1.15% per 0.01 increase in study HDI, 95% CI: −2.24, −0.06%, P = .04; UC HDI: β = −0.66% per 0.01 increase in study HDI, 95% CI: −1.19, −0.12%, P = .02). Discussion We found that placebo clinical response was most susceptible to influences of site-level socioeconomic wellbeing. These findings highlight that estimation of placebo rates in trial planning should account for geographic location of recruiting sites.
Aspirin Use and Liver-Related Outcomes in Metabolic Dysfunction-Associated Steatotic Liver Disease: A Systematic Review and Meta-Analysis
Jamal, Fares , Elshaer, Amani, Claassen, Pierce L., Viggiano, Taylor, Barnhill, Michele , Chascsa, David M. , Aqel, Bashar , Hamad, Abdullah , Chascsa, David M , Aqel, Bashar A. , Lizaola-Mayo, Blanca C, Jamal, Fares , Elshaer, Amani , Viggiano, Taylor , Barnhill, Michele , Vargas, Hugo E. , Lizaola‐Mayo, Blanca

Mayo Clinic

Biomedicines | June 1, 2026 | Volume: 14 | Issue: 6 | Pages: 1249

10.3390/biomedicines14061249 | PMID 42351677 Get It

Background: Given aspirin’s biologic plausibility for antifibrotic and antineoplastic effects, we conducted a systematic review and meta-analysis to examine the association between aspirin use and major liver-related outcomes in metabolic dysfunction-associated steatotic liver disease (MASLD). To our knowledge, this is the first systematic review and meta-analysis restricted exclusively to patients with biopsy- or registry-confirmed MASLD. Methods: A comprehensive search of Ovid MEDLINE, Ovid EMBASE, Scopus, and Web of Science was performed in October 2025. Studies enrolling adults with a confirmed MASLD diagnosis were included; those with viral hepatitis or alcohol-related liver disease were excluded. Outcomes assessed included hepatocellular carcinoma (HCC), fibrosis progression, cirrhosis, all-cause and liver-related mortality, gastrointestinal (GI) bleeding, hemorrhagic stroke, and liver disease progression. Hazard ratios (HRs) with 95% CIs were pooled using random-effects models. Heterogeneity was assessed using I2 statistics. Results: Seven studies met the eligibility criteria, with approximately 720,000 individuals included. Pooled analysis showed that aspirin use was associated with a significantly lower HCC risk (HR 0.59; 95% CI 0.43–0.81; I2 = 83%). No statistically significant association was found between aspirin use and cirrhosis incidence (HR 0.55; 95% CI 0.13–2.37; I2 = 83.4%) or GI bleeding (HR 1.11; 95% CI 0.74–1.66; I2 = 98.9%). Among the two studies that explored all-cause mortality, aspirin was associated with a modest but statistically significant reduction in all-cause mortality (HR 0.86; 95% CI 0.78–0.95; I2 = 0%). Conclusions: Aspirin use is associated with a reduced risk of HCC and all-cause mortality in MASLD without significantly increasing GI bleeding or hemorrhagic strokes. These associations may reflect aspirin’s anti-inflammatory properties in liver disease. Further RCTs are needed to verify the causal role of aspirin in MASLD management.
Efficacy and Safety of Tirofiban for the Management of Acute Ischemic Stroke: A Systematic Review and Meta‐Analysis of Randomized Controlled Trials (RCTs)
Bullecer, Dorothy Lim, Mohammed, Cara, Loiola, Julie Anne de Lima, Chy, Mary Gabrielle Te, Ramli, Samratul Fuadah, Hussein, Abimbola, showkat, wasid bin, Taikadan, Thahsin, Mutyala, Sarika, Ahmad, Adeel, Alsubari, Asma’a Munasar Ali, Bullecer, Dorothy, Loiola, Julie de Lima , Ayyan, Muhammad , Rehman, Muhammad Aemaz Ur

Mayo Clinic

Brain and Behavior | June 1, 2026 | Volume: 16 | Issue: 6 | Pages: No page available

10.1002/brb3.71520 | PMID 42219764 Get It

ABSTRACT Background : Tirofiban is a GP IIb/IIIa inhibitor, an anti‐platelet drug that is used in ischemic stroke or acute coronary syndromes. The goal of this study is to assess the safety and efficacy of the drug in patients who have suffered an acute ischemic stroke. Methods : A comprehensive search of PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov from inception to December 2025 yielded randomized controlled trials (RCTs) comparing Tirofiban and conventional management in patients with acute ischemic stroke. We assessed the risk of bias using the revised Cochrane “Risk of bias” tool for randomized trials (RoB 2.0). We analyzed the outcomes using RevMan 5.4, with risk ratio (RR) as the effect measure. Results : A total of 9 RCTs with 4210 patients were included in our meta‐analysis. According to our meta‐analysis, the tirofiban group was associated with a statistically significant increase in the patients showing functional independence at 90 days, measured by patients with Modified Rankin Score (mRS) of 0–2 (RR 1.13; CI = 1.06–1.20) and excellent outcome (mRS score 0–1) at 90 days (RR 1.17; CI = 1.05–1.29). We found no statistically significant difference between the two groups regarding mortality (RR 0.94; CI = 0.63–1.40). The tirofiban group had an increased incidence of intracranial hemorrhage (ICH) (RR 1.25; CI = 1.06–1.47) but had a similar incidence of symptomatic ICH as compared to the control group (RR 1.48; CI = 0.98–2.24). Conclusion : This meta‐analysis suggests that tirofiban may improve favorable functional outcomes (mRS 0–2) in acute ischemic stroke, although the certainty of evidence was moderate. While no significant increase in sICH was observed, some analyses showed a higher rate of overall intracranial hemorrhage. These findings should therefore be interpreted cautiously, and further high‐quality randomized trials are needed to confirm the efficacy and safety of tirofiban before routine guideline use.
APOE3-Christchurch variant enhances neurovascular support functions of iPSC-derived mesenchymal stromal cells
Martinez, Paula J. Rodriguez, Yslas, Aria R., Inoue, Yasuteru , Parsons, Tammee M., Baker, Samantha K., Lü, Wenyan, Raulin, Ana‐Caroline , Kanekiyo, Takahisa , Rodriguez Martinez, Paula J, Raulin, Ana-Caroline , Yslas, Aria R.

Mayo Clinic

Frontiers in Molecular Biosciences | June 1, 2026 | Volume: 13 | Issue: No issue available | Pages: No page available

10.3389/fmolb.2026.1778856 | PMID 42306774 Get It

Aging and neurodegenerative disorders like Alzheimer’s Disease (AD) are associated with progressive dysfunction of the blood-brain barrier (BBB) and neurovascular unit (NVU), contributing to impaired vascular integrity and neuronal vulnerability. Apolipoprotein E (APOE) is a key regulator of neurovascular function, and the rare APOE3-R136S “Christchurch” variant ( APOE3Ch ) confers protection against AD. Mesenchymal stromal cells (MSCs) represent a promising cell-based therapy for the treatment of neurodegenerative diseases due to their paracrine effect exerted on vascular and neural cells. To investigate how APOE3Ch influences MSC-mediated neurovascular support, we used isogenic iPSC-derived MSCs (iMSCs) with homozygous APOE3Ch or APOE3 . We found that APOE3Ch iMSCs have stronger immunosuppressive effect on LPS-induced NFκB activation of THP1 cells. APOE3Ch iMSCs also enhanced endothelial barrier resistance and angiogenic capacity compared to APOE3 iMSCs when directly co-cultured with endothelial cells. In addition, conditioned medium from APOE3Ch iMSCs promoted neurite outgrowth more efficiently than that from APOE3 iMSCs. Metabolic profiling revealed differences between APOE3Ch and APOE3 iMSCs, suggesting altered metabolic resilience. Together, these findings demonstrate that iMSCs support vascular and neuronal function through paracrine mechanisms and suggest that APOE3Ch variant improves specific aspects of MSC-mediated neurovascular support. This work highlights the potential of combining MSC-based therapies with protective APOE variants to target BBB and NVU dysfunction in aging and neurodegeneration.
Current views on sustainability in urology: findings from the North Central Section of American Urological Association membership survey
Shi, Chloe, Wang, Susanna, Steinberg, Ryan, DeLancy, John O., Goh, Keow, Adelstein, Sarah, Dangle, Pankaj, Lin, Frank C., Miller, AR, Gettman, Matthew, Steinberg, Ryan L. , Miller, Adam , Adelstein, Sarah A. , Dangle, Pankaj , Lin, Frank C.

Mayo Clinic

Frontiers in Urology | June 1, 2026 | Volume: 6 | Issue: No issue available | Pages: No page available

10.3389/fruro.2026.1818561 | PMID 42305906 Get It

Objective The United Nations defines sustainability as meeting needs of the present without compromising future generations. While often equated to “saving the planet”, sustainability is a diverse topic. Healthcare generates &gt;5% of CO 2 emissions worldwide, yet sustainability efforts in urology are limited. The North Central Section of the American Urological Association (NCSAUA) recently convened a Sustainability Task Force to address this topic. This study queried members on sustainability in urologic practice. Methods Following literature review on sustainability in surgery/urology, a 19-item anonymous REDCap survey was developed and distributed via email to NCSAUA members (N = 1607). The survey assessed current best practice, institutional/personal sustainability, and demographics. Responses were compiled and summarized using descriptive statistics. Results Survey response rate was 4.9% (79/1607). Respondents were most commonly from metropolitan areas (82%), male (71%), and in practice for 5–14 years (29%). Sustainability topics were prioritized as: (1) financial, (2) future workforce, (3) environmental. Over half (56%) reported no institutional sustainability programs or were unaware of them. Instrument (67%), computer (68%), and paper (65%) recycling were supported by a majority of respondents. However, only 28% and 29% of respondents reported current institutional use of instrument and computer recycling, respectively. Telemedicine was infrequent, with most urologists (58%) conducting 0-5% of visits virtually. Conclusions Current institutional and urologic practice emphasis on sustainability is low. Respondents ranked highest sustainability priorities as financial and future workforce. Efforts to address environmental sustainability were also supported, namely reduction of disposables and waste. The findings support the development of targeted programs to advance sustainability priorities widely.
Comparative evaluation of the Mayo Clinic Florida microdosimetric kinetic model and mMKM for carbon ion treatment planning: A matRad‐based analysis
Liang, Xiaoying, Park, Chunjoo, Lu, Bo, Tan, Jun , Seckler, Lisa, Cristoforetti, Remo , Inaniwa, Taku, Beltran, Chris J., Hartzell, Shannon , Yaddanapudi, Sridhar , Furutani, Keith M. , Parisi, Alessio , Liang, Xiaoying, Lu, Bo , Inaniwa, Taku , Wahl, Niklas , Beltran, Chris

Mayo Clinic

Journal of Applied Clinical Medical Physics | June 1, 2026 | Volume: 27 | Issue: 5 | Pages: No page available

10.1002/acm2.70645 | PMID 42219622 Get It

Abstract Purpose Modeling relative biological effectiveness (RBE) is central to carbon ion radiotherapy treatment planning. The modified Microdosimetric Kinetic Model (mMKM) is a clinically established RBE framework that has guided treatment protocols at many existing carbon centers, while the Mayo Clinic Florida Microdosimetric Kinetic Model (MCF MKM) is a recently developed alternative. This work aims to implement the MCF MKM in the open‐source treatment planning system matRad and to quantitatively compare its RBE‐weighted dose predictions with those of the clinically established mMKM using identical physical dose distributions across multiple disease sites. These findings will help assess their dosimetric equivalence and inform protocol development for carbon ion radiotherapy at MCF. Methods Monte Carlo simulations of the MCF carbon beamline were performed to generate physical (IDD, LET, lateral spread) and biological base data for integration of each RBE model into matRad . Treatment plans were generated for six patients, each corresponding to a different disease site, using clinical beam configurations with carbon‐reference dose prescriptions, and plans were optimized using the MCF MKM. To isolate differences attributable solely to the RBE model, the resulting physical dose distributions were held fixed and RBE‐weighted doses were recalculated using the mMKM. Dose volume histogram (DVH) metrics and spatial dose‐difference maps were used to compare target coverage and organ‐at‐risk doses between the two models. Results Across patient cases, RBE‐weighted dose distributions from MCF MKM and mMKM showed strong agreement. Differences in target coverage were small, with CTV D95% differing by less than 1.6% across all disease sites and maximum target dose differences not exceeding 0.88%. Organ‐at‐risk dose deviations were limited, with differences of 3.0% or less across evaluated DVH metrics. Spatial dose‐difference maps showed that the largest discrepancies occurred in regions of steep dose gradients near target to organ‐at‐risk interfaces, while overall dose conformity and plan quality remained comparable between the two models. Conclusions: This study served as the first systematic model comparison of the MCF MKM and mMKM within a treatment planning environment. These findings suggest that the MCF MKM and mMKM produce dosimetrically consistent RBE‐weighted dose predictions under realistic planning conditions using carbon‐reference parameters. Accordingly, the fractionation schemes developed from years of clinical experience with mMKM implementations may serve as a practical foundation for protocol development at MCF.
Functional Characterization of Myeloid Neoplasm-associated DDX41 Variants Reveals Pathogenic Interaction with Acquired Hotspot Mutation
Fisher, Julianna, Stepanchick, Emily , Wilson, Andrew, 潤一郎, 木田, Adam, Mike , Otero, Mariela V. Perez, Badar, Talha, Kusne, Yael, Ferrer, Alejandro, Patnaik, Mrinal M., Kida, Jun‐ichiro , Badar, Talha , Kusne, Yael , Ferrer, Alejandro , Patnaik, Mrinal M. , Chlon, Timothy M.

Mayo Clinic

No container title available | June 1, 2026 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.64898/2026.05.27.727893 Get It

Abstract Germline variants in DDX41 are the most frequent genetic predisposition to adult hematologic malignancies. The most common variants are truncating, implicating loss of function in the pathogenesis. However, non-truncating variants account for 30-40% of cases, and their impact on essential DDX41 functions remains unknown. We utilized a genetic complementation assay to assess the functionality of 10 recurrent germline non-truncating variants of DDX41. All variants restored viability to Ddx41 -deficient hematopoietic progenitor cells at exogenous expression levels. In contrast, the hotspot mutant p.R525H, which is somatically acquired at disease onset in >50% of patients, failed to restore viability. CRISPR-based modeling in cell lines and mice revealed heterogeneity: some variants were non-functional at endogenous expression levels whereas others maintained complete functionality, supporting normal cell proliferation and even lifelong hematopoiesis in a homozygous setting. Notably, co-expression of p.R525H with some variants caused impaired hematopoietic progenitor cell viability, indicating a dominant-negative effect of p.R525H. In contrast, other variants, all classified as variants of unknown significance, were unaffected by the presence of p.R525H. A screen of 100 disease-associated variants confirmed that many non-truncating germline variants are susceptible to p.R525H-mediated dominant-negative effects, whereas wild-type DDX41 is not. These findings indicate that DDX41 variant curation is complicated by variable effects on functionality and variant-specific interactions with somatically-acquired DDX41 mutations. The dominant-negative effect of p.R525H provides a mechanistic basis for the conclusion of recent patient cohort analyses that co-occurrence with a somatic hotspot mutation is a reliable indicator of DDX41-driven disease in carriers of non-truncating variants.