NF2-related Schwannomatosis Diagnosed Before and After 30 Years of Age: Differences in Disease Presentation and Rates of Positive Genetic Testing.
OBJECTIVE: Characterize pathogenic variants, rates of mosaicism, genetic testing yield, and disease severity among patients with NF2-related schwannomatosis dichotomized by diagnosis before or after the age of 30. STUDY DESIGN: Retrospective analysis. SETTING: Tertiary referral center multidisciplinary NF2 clinic from 2021 to 2024. PATIENTS: Patients with NF2-related schwannomatosis. INTERVENTION: Next-generation sequencing. MAIN OUTCOME MEASURE: Rates of mosaicism, genetic testing rates and yield, and overall disease severity by tumor burden. RESULTS: From 2021 to 2024, there were 32 patients ≥30 years of age and 39 patients diagnosed at younger ages. Patients diagnosed ≥30 years exhibited decreased likelihood of receiving genetic testing (53% vs. 85%; P =0.009) and decreased genetic yield (defined as identification of a pathogenic genetic variant in those undergoing testing; 65% vs. 85%; P =0.20). Both age groups demonstrated similar rates of pathogenic variant type with loss-of-function being the predominant variant detected in 73% vs. 67%, for ≥30 vs. <30 years of age; P =0.90. Those ≥30 years harbored fewer number of average anatomic regions involved by tumor (2.3 vs. 3.4; P <0.001) and decreased total number of tumors (7 vs. 12; P <0.001). CONCLUSIONS: Patients diagnosed with NF2-related schwannomatosis at age ≥30 years exhibited reduced disease severity compared with those diagnosed at a younger age despite harboring similar distributions of genetic pathogenic variants inclusive of loss-of-function pathogenic variants. These observations emphasize the importance of considering patient age in addition to genetic testing for diagnostic framing tailored to patients' biology and clinical context to optimize care in the setting of NF2-related schwannomatosis.