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Vestibular schwannomas are benign nerve sheath tumours that arise on the vestibulocochlear nerves. Vestibular schwannomas are known to occur in the context of tumour predisposition syndromes NF2 -related and LZTR1 -related schwannomatosis. However, the majority of vestibular schwannomas present sporadically without identification of germline pathogenic variants. To identify novel genetic associations with risk of vestibular schwannoma development, we conducted a genome-wide association study in a cohort of 911 sporadic vestibular schwannoma cases collated from the neurofibromatosis type 2 genetic testing service in the north-west of England, UK and 5500 control samples from the UK Biobank resource. One risk locus reached genome-wide significance in our association analysis (9p21.3, rs1556516, P = 1.47 × 10−13, odds ratio = 0.67, allele frequency = 0.52). 9p21.3 is a genome-wide association study association hotspot, and a number of genes are localized to this region, notably CDKN2B-AS1 and CDKN2A/B , also referred to as the INK4 locus. Dysregulation of gene products within the INK4 locus have been associated with multiple pathologies and the genes in this region have been observed to directly impact the expression of one another. Recurrent associations of the INK4 locus with components of well-described oncogenic pathways provides compelling evidence that the 9p21.3 region is truly associated with risk of vestibular schwannoma tumorigenesis. [ABSTRACT FROM AUTHOR]

Objectives: Schwannomatosis is a dominantly inherited condition predisposing to schwannomas of mainly spinal and peripheral nerves with some diagnostic overlap with neurofibromatosis-2 (NF2), but the underlying epidemiology is poorly understood. We present the birth incidence and prevalence allowing for overlap with NF2., Methods: Schwannomatosis and NF2 cases were ascertained from the Manchester region of England (population=4.8 million) and from across the UK. Point prevalence and birth incidence were calculated from regional birth statistics. Genetic analysis was also performed on NF2 , LZTR1 and SMARCB1 on blood and tumour DNA samples when available., Results: Regional prevalence for schwannomatosis and NF2 were 1 in 126 315 and 50 500, respectively, with calculated birth incidences of 1 in 68 956 and 1 in 27 956. Mosaic NF2 causes a substantial overlap with schwannomatosis resulting in the misdiagnosis of at least 9% of schwannomatosis cases. LZTR1 -associated schwannomatosis also causes a small number of cases that are misdiagnosed with NF2 (1%-2%), due to the occurrence of a unilateral vestibular schwannoma. Patients with schwannomatosis had lower numbers of non-vestibular cranial schwannomas, but more peripheral and spinal nerve schwannomas with pain as a predominant presenting symptom. Life expectancy was significantly better in schwannomatosis (mean age at death 76.9) compared with NF2 (mean age at death 66.2; p=0.004)., Conclusions: Within the highly ascertained North-West England population, schwannomatosis has less than half the birth incidence and prevalence of NF2., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)