PSENEN and histiocytic sarcoma: 48 Next-generation sequencing of the entire NCSTN gene was initially performed in samples from 95 subjects enrolled in either study and select variants found in these subjects were further evaluated in 443 subjects with HS.48 One missense NCTSN mutation was identified in a patient without a family history of HS.48 Liu et al.56 reported a 29-year-old male smoker with no family history of HS who had a deletion mutation in PSENEN, which was the first time a PSENEN mutation was reported in a sporadic case of HS.