RHABDOID TUMOURS PREDISPOSITION SYNDROME 2
Investigation of two sisters with ATRT/MRT who did not show abnormal BAF47/SMARCB1/INI1 immunohistochemical staining or germline or somatic mutations in SMARCB1 led to the identification of germline mutations in the partner molecule BRG1/SMARCA4 (Schneppenheim et al. 2010). As for SMARCB1, immunohistochemical testing showed loss of BRG1/SMARCA4 in the Tumours. The mutation was transmitted from an unaffected father. A second family containing a nine-month-old boy with an ATRT and a germline mutation in SMARCA4 has also been reported (Hasselblatt et al. 2011). Therefore testing of SMARCA4 might be indicated if the immunohistochemical staining of an ATRT/MRT for BAF47/INI1 is normal. The full spectrum of diseases associated with germline SMARCA4 mutations remains to be determined.