Wadsworth Paul A, Chen Simon B, Lawrence Lauren, Ho Chandler C, Le Joseph E, Libiran Paolo, Grayson Peter C, Ferrada Marcela A, Beck David B, Suarez Carlos J
Department of Pathology, Stanford University School of Medicine, Stanford, CA, United States.
Present affiliation: Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.
Am J Clin Pathol. 2025 Sep 9;164(3):360-366. doi: 10.1093/ajcp/aqaf051.
VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) is a recently described autoinflammatory syndrome caused by pathogenic variants in UBA1. However, there is a dearth of widely available UBA1 testing aside from large, expensive sequencing studies. Thus, we sought to rapidly develop, validate, and clinically deploy a cost-effective assay for detecting the most common UBA1 variants.
We developed, validated, and implemented a single base extension mass spectrometry assay for detecting pathogenic UBA1 variants at the c.121, c.122, and c.118-1 positions in patients with suspected VEXAS syndrome. Assay performance characteristics were assessed using peripheral blood and bone marrow samples from patients with (n = 8) and without (n = 36) VEXAS.
The assay demonstrated a lower limit of detection (LOD) of 10% variant allele fraction for each mutation. The analytical accuracy, sensitivity, and specificity were each demonstrated to be 100% at the LOD, with excellent intra- and interrun reproducibility. Based on literature review of reported UBA1 variants associated with VEXAS, to date, this assay detects the most prevalent variants, with a clinical sensitivity of 97% or more.
A cost-effective, mass spectrometry-based assay with high analytical and clinical performance can feasibly be implemented in hospital laboratories for diagnosis of VEXAS syndrome.
VEXAS（空泡、E1酶、X连锁、自身炎症性、体细胞）是一种最近被描述的由UBA1基因致病性变异引起的自身炎症综合征。然而，除了大型、昂贵的测序研究外，缺乏广泛可用的UBA1检测方法。因此，我们试图快速开发、验证并在临床上应用一种经济有效的检测方法来检测最常见的UBA1变异。
我们开发、验证并实施了一种单碱基延伸质谱分析法，用于检测疑似VEXAS综合征患者中位于c.121、c.122和c.118-1位置的致病性UBA1变异。使用来自患有（n = 8）和未患有（n = 36）VEXAS的患者的外周血和骨髓样本评估检测性能特征。
该检测方法对每个突变的检测下限（LOD）为10%变异等位基因分数。在检测下限处，分析准确性、灵敏度和特异性均显示为100%，批内和批间重复性良好。基于对已报道的与VEXAS相关的UBA1变异的文献综述，迄今为止，该检测方法可检测到最常见的变异，临床灵敏度达到97%或更高。
一种具有高分析性能和临床性能的经济有效的基于质谱的检测方法可以在医院实验室中切实可行地用于VEXAS综合征的诊断。
