Systematic Reclassification of FLNB Variants of Uncertain Significance in Larsen Syndrome

Abstract Objectives The aimed to re-evaluate eighteen (18) Variants of Uncertain Significance (VUS) in the FLNB gene to test the effectiveness of the ACMG/AMP guidelines and assess their clinical implications in probands with Larsen Syndrome (LRS, OMIM 150250). Methods The methodology followed the steps listed in the ACMG/AMP guidelines, selecting VUS in FLNB previously functionally studied and compared with the classifications available in the ClinVar database. The VUS were analyzed for frequency in secondary databases and of functional and structural impact was performed using the meta-prediction software CADD and REVEL. Family segregation, data obtained from LOVD and HGMD. The clinical data analyzed were collected from ClinVar, VarSome, and PubMed. Results After reclassification, 8 (44.4%) were reclassified as Pathogenic (P) and 8 (44.4%) as Likely Pathogenic (LP), while 2 (11.1%) remained as VUS due to insufficient or conflicting evidence. The reclassifications were primarily driven by computational evidence (PP3), population data (PM2), and available clinical data (PP4). However, a significant proportion of variants lacked primary clinical or segregation data, which represents a major limitation of this study. Discussion This research demonstrates the value of systematically applying ACMG/AMP guidelines to reduce the diagnostic uncertainty of VUS in LRS. However, it also highlights the critical dependence on publicly available, high-quality clinical and segregation data. The reclassification of these variants has direct implications for clinical management, including genetic counselling, surveillance, and therapeutic interventions, while emphasising the urgent need for data sharing initiatives to resolve the remaining uncertainties.