rs769023941

chr22-23825375-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM2 PP2 PP3_Strong

The NM_003073.5(SMARCB1):c.946C>T(p.Arg316Trp) variant causes a missense change. The variant allele was found at a frequency of 0.00000342 in 1,461,786 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R316Q) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: SMARCB1 NM_003073.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 4.99

Genes affected

SMARCB1 (HGNC:11103): (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1) The protein encoded by this gene is part of a complex that relieves repressive chromatin structures, allowing the transcriptional machinery to access its targets more effectively. The encoded nuclear protein may also bind to and enhance the DNA joining activity of HIV-1 integrase. This gene has been found to be a tumor suppressor, and mutations in it have been associated with malignant rhabdoid tumors. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Dec 2015]

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, SMARCB1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.973

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SMARCB1	NM_003073.5	c.946C>T	p.Arg316Trp	missense_variant	7/9	ENST00000644036.2
SMARCB1	NM_001362877.2	c.1000C>T	p.Arg334Trp	missense_variant	7/9
SMARCB1	NM_001317946.2	c.973C>T	p.Arg325Trp	missense_variant	7/9
SMARCB1	NM_001007468.3	c.919C>T	p.Arg307Trp	missense_variant	7/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SMARCB1	ENST00000644036.2	c.946C>T	p.Arg316Trp	missense_variant	7/9		NM_003073.5	A1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000796 AC: 2 AN: 251354 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135858

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461786 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 727182

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000450

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	curation	Sema4, Sema4	Feb 07, 2022	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Mar 14, 2023	The p.R316W variant (also known as c.946C>T), located in coding exon 7 of the SMARCB1 gene, results from a C to T substitution at nucleotide position 946. The arginine at codon 316 is replaced by tryptophan, an amino acid with dissimilar properties. This variant has been detected in multiple individuals with no reported features of Coffin-Siris syndrome (Ambry internal data). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Missense and in-frame variants in SMARCB1 are known to cause neurodevelopmental disorders; however, such associations with rhabdoid tumor predisposition syndrome are exceedingly rare (Kosho T et al. Am J Med Genet C Semin Med Genet. 2014 Sep;166C(3):262-75; Eaton KW et al. Pediatr Blood Cancer. 2011 Jan;56(1):7-15). Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Nov 14, 2023

This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 316 of the SMARCB1 protein (p.Arg316Trp). This variant is present in population databases (rs769023941, gnomAD 0.002%). This variant has not been reported in the literature in individuals affected with SMARCB1-related conditions. ClinVar contains an entry for this variant (Variation ID: 464341). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt SMARCB1 protein function with a positive predictive value of 80%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.36
Cadd	Pathogenic	34
Dann	Pathogenic	1.0
Eigen	Pathogenic	0.93
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	0.97	D
M_CAP	Pathogenic	0.40	D
MetaRNN	Pathogenic	0.97	D;D;D;D
MetaSVM	Uncertain	0.74	D
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.93	D
PROVEAN	Pathogenic	-7.3	D;.;D;.
REVEL	Pathogenic	0.80
Sift	Pathogenic	0.0	D;.;D;.
Sift4G	Pathogenic	0.0	D;.;D;.
Polyphen		1.0	.;D;D;.
Vest4		0.89
MutPred		0.88		.;.;Loss of MoRF binding (P = 0.1432);.;
MVP		0.88
MPC		2.6
ClinPred		1.0	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.99
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs769023941; hg19: chr22-24167562; COSMIC: COSV54094093;