rs1298640170

Positions:

• chr22-23803427-A-C
• chr22-23803427-A-G

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_003073.5(SMARCB1):​c.628+5A>C variant causes a splice donor 5th base, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,732 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: SMARCB1 NM_003073.5 splice_donor_5th_base, intron
• Scores: Splicing: ADA: 0.0007403
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.804

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_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.85).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SMARCB1	NM_003073.5	c.628+5A>C		splice_donor_5th_base_variant, intron_variant		ENST00000644036.2	NP_003064.2
SMARCB1	NM_001007468.3	c.601+5A>C		splice_donor_5th_base_variant, intron_variant			NP_001007469.1
SMARCB1	NM_001317946.2	c.655+5A>C		splice_donor_5th_base_variant, intron_variant			NP_001304875.1
SMARCB1	NM_001362877.2	c.682+5A>C		splice_donor_5th_base_variant, intron_variant			NP_001349806.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SMARCB1	ENST00000644036.2	c.628+5A>C		splice_donor_5th_base_variant, intron_variant			NM_003073.5	ENSP00000494049	A1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461732 Hom.: 0 Cov.: 34 AF XY: 0.00000138 AC XY: 1 AN XY: 727160

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

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

Aug 08, 2023

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. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant is not likely to affect RNA splicing. ClinVar contains an entry for this variant (Variation ID: 664339). This variant has not been reported in the literature in individuals affected with SMARCB1-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change falls in intron 5 of the SMARCB1 gene. It does not directly change the encoded amino acid sequence of the SMARCB1 protein. It affects a nucleotide within the consensus splice site. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 31, 2022

The c.628+5A>C intronic variant results from an A to C substitution 5 nucleotides after coding exon 5 in the SMARCB1 gene. This nucleotide position is poorly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will not have any significant effect on splicing. 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_noAF	Benign	-0.85
CADD	Benign	9.9
DANN	Benign	0.43
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.3

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.00074
dbscSNV1_RF	Benign	0.11
SpliceAI score (max)		0.010		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: rs1298640170; hg19: chr22-24145614;