We found underlying NF2 or mutations in NF2 in 45% of cases (n = 63; Fig. 2a): 14% of SP-EPN samples were obtained from patients with known NF2 (n = 19) and 31% of samples had NF2 mutations (n = 43) or homozygous loss of NF2 (n = 1) that were detected only in tumor material with no available blood analysis and no documented clinical criteria of NF2 (Fig. 2a). Here, NF2 is linked to neoplasm.