19-11039554-G-C

Position:

• chr19-11039554-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PVS1_Moderate PM2

The NM_001387283.1(SMARCA4):​c.4266+1G>C variant causes a splice donor change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: SMARCA4 NM_001387283.1 splice_donor
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: -0.196

Genes affected

SMARCA4 (HGNC:11100): (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 4) The protein encoded by this gene is a member of the SWI/SNF family of proteins and is similar to the brahma protein of Drosophila. Members of this family have helicase and ATPase activities and are thought to regulate transcription of certain genes by altering the chromatin structure around those genes. The encoded protein is part of the large ATP-dependent chromatin remodeling complex SNF/SWI, which is required for transcriptional activation of genes normally repressed by chromatin. In addition, this protein can bind BRCA1, as well as regulate the expression of the tumorigenic protein CD44. Mutations in this gene cause rhabdoid tumor predisposition syndrome type 2. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, May 2012]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.018849207 fraction of the gene. Cryptic splice site detected, with MaxEntScore 7.4, offset of -11, new splice context is: cacGTgcgt. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SMARCA4	NM_001387283.1	c.4266+1G>C		splice_donor_variant		ENST00000646693.2	NP_001374212.1
SMARCA4	NM_003072.5	c.4171-1753G>C		intron_variant		ENST00000344626.10	NP_003063.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SMARCA4	ENST00000646693.2	c.4266+1G>C		splice_donor_variant			NM_001387283.1	ENSP00000495368
SMARCA4	ENST00000344626.10	c.4171-1753G>C		intron_variant		1	NM_003072.5	ENSP00000343896	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 26

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Rhabdoid tumor predisposition syndrome 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 09, 2021

This sequence change affects a donor splice site in intron 30 of the SMARCA4 gene. Loss-of-function variants in SMARCA4 are known to be pathogenic (PMID: 24658001, 24658002). However, tissue-specific alternative splicing of SMARCA4 gene results in functional isoforms lacking in-frame exon 30 (also known as exon 28B, PMID: 18437052). For this reason the clinical significance of loss of function variants in exon 30 is currently uncertain. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with SMARCA4-related conditions. ClinVar contains an entry for this variant (Variation ID: 470387). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 03, 2023

The c.4266+1G>C intronic variant results from a G to C substitution one nucleotide after coding exon 29 of the SMARCA4 gene. This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will not have any significant effect on splicing. RNA studies have demonstrated that this alteration results in a transcript predicted to lead to a protein with an in-frame loss of the 32 amino acids of coding exon 29. However, the exact functional impact of the deleted amino acids is unknown as this region of the SMARCA4 gene is excluded from other biologically relevant transcripts (Ambry internal data). Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.33	T
BayesDel_noAF	Benign	-0.71
CADD	Benign	17
DANN	Benign	0.86
Eigen	Benign	-0.57
Eigen_PC	Benign	-0.75
FATHMM_MKL	Benign	0.0060	N
MutationTaster	Benign	1.0	N;N;N;N;N;N;N;N;N
GERP RS		0.54
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.91
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: rs1060502086; hg19: chr19-11150230;