22-23801047-A-G

Position:

• chr22-23801047-A-G

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 3P and 2B. PM2 PP2 BP4_Moderate

The NM_003073.5(SMARCB1):​c.466A>G​(p.Met156Val) variant causes a missense change. The variant allele was found at a frequency of 0.00000205 in 1,461,882 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: SMARCB1 NM_003073.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 4.82

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]

SMARCB1 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), SMARCB1. . Gene score misZ 3.6016 (greater than the threshold 3.09). Trascript score misZ 4.8554 (greater than threshold 3.09). GenCC has associacion of gene with schwannomatosis 1, familial multiple meningioma, rhabdoid tumor predisposition syndrome 1, complex neurodevelopmental disorder, intellectual disability, autosomal dominant 15, familial rhabdoid tumor, schwannomatosis, Coffin-Siris syndrome.
• BP4: Computational evidence support a benign effect (MetaRNN=0.23051742).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SMARCB1	NM_003073.5	c.466A>G	p.Met156Val	missense_variant	4/9	ENST00000644036.2	NP_003064.2
SMARCB1	NM_001362877.2	c.466A>G	p.Met156Val	missense_variant	4/9		NP_001349806.1
SMARCB1	NM_001317946.2	c.439A>G	p.Met147Val	missense_variant	4/9		NP_001304875.1
SMARCB1	NM_001007468.3	c.439A>G	p.Met147Val	missense_variant	4/9		NP_001007469.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SMARCB1	ENST00000644036.2	c.466A>G	p.Met156Val	missense_variant	4/9		NM_003073.5	ENSP00000494049.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251482 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135916

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: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461882 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727240

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: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 01, 2018

This sequence change replaces methionine with valine at codon 156 of the SMARCB1 protein (p.Met156Val). The methionine residue is moderately conserved and there is a small physicochemical difference between methionine and valine. This variant is present in population databases (rs540120954, ExAC <0.01%) but has not been reported in the literature in individuals with a SMARCB1-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies. In summary, this variant is a rare missense change that is not predicted to affect protein function. There is no indication that it causes disease, but the available evidence is currently insufficient to prove that conclusively. Therefore, it has been classified as a Variant of Uncertain Significance. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 07, 2022

The p.M156V variant (also known as c.466A>G), located in coding exon 4 of the SMARCB1 gene, results from an A to G substitution at nucleotide position 466. The methionine at codon 156 is replaced by valine, an amino acid with highly similar properties. This amino acid position is well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. 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). Based on the supporting evidence, the association of this alteration with Coffin-Siris syndrome is unknown; however, the association of this alteration with rhabdoid tumor predisposition syndrome is unlikely. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.069
BayesDel_addAF	Uncertain	0.11	D
BayesDel_noAF	Benign	-0.090
CADD	Benign	19
DANN	Benign	0.86
DEOGEN2	Benign	0.26	.;T;T;T
Eigen	Benign	-0.45
Eigen_PC	Benign	-0.16
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Uncertain	0.90	.;.;.;D
M_CAP	Benign	0.041	D
MetaRNN	Benign	0.23	T;T;T;T
MetaSVM	Uncertain	-0.16	T
MutationAssessor	Benign	-0.28	.;N;.;.
PrimateAI	Pathogenic	0.81	D
PROVEAN	Benign	-0.19	N;.;N;N
REVEL	Uncertain	0.38
Sift	Benign	1.0	T;.;T;T
Sift4G	Benign	1.0	T;.;T;T
Polyphen		0.0, 0.55	.;B;B;P
Vest4		0.38
MutPred		0.41		Loss of disorder (P = 0.1197);.;Loss of disorder (P = 0.1197);.;
MVP		0.69
ClinPred		0.38	T
GERP RS		4.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.22
gMVP		0.53

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: rs540120954; hg19: chr22-24143234;