HTRA1 and schwannoma: Mansouri et al. [111] observed that a significant proportion of painful schwannomas in patients with SWN affected the lower extremities, occurring predominantly in females and particularly in those with germline PVs in LZTR1. Furthermore, 16% of the very painful schwannomas were positive for the somatic SH3PXD2A-HTRA1 gene fusion [111] (Sect.