Variant Resolution Through RNA Testing and Affected Tissue Analysis in the Neurofibromatoses: A Case Series

This series reports 3 unrelated individuals with features of neurofibromatosis type 1 (NF1) and/or schwannomatosis (SWN) in whom variants of uncertain significance (VUSs) were resolved through RNA testing and tissue analysis, highlighting the clinical impact of these tests.

Each patient's genetic testing identified a VUS that could have explained their clinical presentation. Because diagnostic criteria were not met, we performed VUS resolution. For patient 1, we conducted tissue analysis and RNA-based Sanger sequencing. For patients 2 and 3, RNA-based Sanger sequencing was pursued.

Tissue analysis and RNA testing reclassified the NF1 c.8050 + 93A>T VUS in patient 1 as pathogenic, confirming diagnosis of NF1. RNA testing of the NF2 c.448-5T>C VUS in patient 2 reclassified the variant as likely benign, ruling out diagnosis of germline neurofibromatosis type 2 (NF2). RNA testing of the SPRED1 c.377-13T>A VUS in patient 3 reclassified the variant as likely benign, ruling out diagnosis of germline Legius syndrome.

Because diagnostic criteria for NF1 and SWN include genetic testing, resolving VUSs in those who do not meet criteria is crucial for clinical care. In this article, we report 3 cases in which RNA testing and tissue analysis clarified pathogenicity of VUSs, thereby affecting clinical care, and in one case providing a definitive diagnosis.