INI1/RCB1/|BAF47 tumour suppressor gene

The gene variously known as hSNF/INI1/SMARCB1/|BAF47 is a putative tumour suppressor gene located on chromosome 22q11.2. It is a member of the SWI/SWF chromatin-remodelling complex and is normally expressed in all tissues.

Staining is nuclear. An antibody reactive with the gene product in formalin-fixed paraffin-embedded tissues is available. Inactivation of the gene occurs in most malignant rhabdoid tumours and loss of staining is potentially diagnostically useful. INI1 mutation does not appear to result in cytoplasmic accumulation of the protein. Negativity occurs even in those malignant rhabdoid tumours in which there is no INI1 deletion or mutation: the mechanism in these cases is not known.

	Renal rhabdoid tumour	0/29 (14 of the 19 cases tested shows INI1 deletion or mutation)1
	Extra-renal rhabdoid tumour	0/15 (7 of the 8 cases tested shows INI1 deletion or mutation)1
	CNS atypical teratoid/rhabdoid tumour	0/20 (all cases confirmed by INI1 mutations)2
	Ewing's sarcoma	13/13 (all cases confirmed by EWS-FL1/ERG positivity)1
	CNS PNET	10/102
	Alveolar rhabdomyosarcoma	3/3 (all cases confirmed by PAX3/7-FKHR positivity)1
	Embryonal rhabdomyosarcoma	2/2 (both cases PAX3/7-FKHR negative)1
	DSRCT	5/5 (all cases confirmed by EWS-WT1 positivity)1
	Renal clear cell sarcoma	4/41
	Wilm's tumour	6/61
	Undifferentiated sarcoma	2/2 (both cases negative for INI1 deletion or mutation)1
	Cellular congenital mesoblastic nephroma	4/41
	Epithelioid sarcoma†	2/2 (focal in one case)1
	Synovial sarcoma	4/4 focal1
	Childhood choroid plexus tumour	5/52
	Childhood craniopharyngeoma	2/22
	Childhood ependymoma	2/22
	Childhood oligodendroglioma	1/22
	Childhood astrocytoma	2/22
	Childhood CNS ganglioglioma	2/22
	Childhood mixed anaplastic oligoastrocytoma	1/1, focal2
	Childhood glioblastoma multiforme	2/22
	Childhood pilocytic astrocytoma	2/22
	Childhood pituitary adenoma	equivocal in one case2
	Childhood CNS germ cell tumour	2/22

^†Epithelioid sarcoma commonly shows loss of alleles from chromosome 22.

References

¹Hoot, A. C., P. Russo, et al. (2004). "Immunohistochemical analysis of hSNF5/INI1 distinguishes renal and extra-renal malignant rhabdoid tumors from other pediatric soft tissue tumors." Am J Surg Pathol 28(11): 1485-91.

²Judkins, A. R., J. Mauger, et al. (2004). "Immunohistochemical analysis of hSNF5/INI1 in pediatric CNS neoplasms." Am J Surg Pathol 28(5): 644-50.

This page last revised 4.1.2005.

©SMUHT/PW Bishop