SMARCA4 and Treacher-Collins syndrome: Concomitant mutations in two or more SWI/SNF genes have not been described in TCS to date, but do occur in SMARCA4-deficient carcinoma, olfactory carcinoma and neuroendocrine carcinomas [25,40,41,42,43,44,45]—tumors that with TCS may be regarded as different morphotypes of one tumor entity [24,25,46].