rs1555787120

Positions:

• chr19-11039466-AGG-AC

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PVS1 PM2

The NM_001387283.1(SMARCA4):​c.4180_4181delinsC​(p.Gly1394GlnfsTer101) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. G1394G) has been classified as Uncertain significance. Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SMARCA4 NM_001387283.1 frameshift
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.730

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 Pathogenic. Variant got 10 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SMARCA4	NM_001387283.1	c.4180_4181delinsC	p.Gly1394GlnfsTer101	frameshift_variant	30/36	ENST00000646693.2
SMARCA4	NM_003072.5	c.4171-1840_4171-1839delinsC		intron_variant		ENST00000344626.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SMARCA4	ENST00000646693.2	c.4180_4181delinsC	p.Gly1394GlnfsTer101	frameshift_variant	30/36		NM_001387283.1
SMARCA4	ENST00000344626.10	c.4171-1840_4171-1839delinsC		intron_variant		1	NM_003072.5	P4

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

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

Invitae

Oct 16, 2023

This sequence change creates a premature translational stop signal (p.Gly1394Glnfs*101) in 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. Information on the frequency of this variant in the gnomAD database is not available, as this variant may be reported differently in the database. This premature translational stop signal has been observed in individual(s) with epthelial ovarian cancer (PMID: 29204511). 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

Jun 10, 2024

The c.4180_4181delGGinsC variant, located in coding exon 29 of the SMARCA4 gene, results from the deletion of two nucleotides and insertion of one nucleotide causing a translational frameshift with a predicted alternate stop codon (p.G1394Qfs*101). This alteration is expected to result in premature protein truncation or nonsense-mediated mRNA decay. Loss-of-function variants in SMARCA4 are known to cause rhabdoid tumor predisposition syndrome including small cell carcinoma of the ovary-hypercalcemic type (SCCOHT); however, such associations with neurodevelopmental disorders are exceedingly rare (Kosho T et al. Am J Med Genet C Semin Med Genet. 2014 Sep;166C(3):262-75; Jelinic P et al. Nat Genet. 2014 May;46(5):424-6). However, this region of the SMARCA4 gene is excluded from other biologically relevant transcripts. Based on the supporting evidence, the association of this alteration with rhabdoid tumor predisposition syndrome is unknown; however, the association of this alteration with Coffin-Siris syndrome is unlikely. -

Computational scores

Source: dbNSFP v4.3

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555787120; hg19: chr19-11150143;