Genetic Variant SMARCB1:n.777A>C (chr22-23801195-A-C) – ACMG Classification: Likely_benign (-2 pts)

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2BP4_Strong

The ENST00000491967.2(SMARCB1):n.777A>C variant causes a non coding transcript exon change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000786 in 1,272,212 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 7.9e-7 ( 0 hom. )

Consequence

SMARCB1
ENST00000491967.2 non_coding_transcript_exon

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 0.125

Publications

0 publications found

Variant links:

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 Gene-Disease associations (from GenCC):

Coffin-Siris syndrome
Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, ClinGen
intellectual disability, autosomal dominant 15
Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae)
rhabdoid tumor predisposition syndrome 1
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Genomics England PanelApp, Ambry Genetics, Labcorp Genetics (formerly Invitae), ClinGen
SMARCB1-related schwannomatosis
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Ambry Genetics
familial multiple meningioma
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
familial rhabdoid tumor
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
schwannomatosis
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
complex neurodevelopmental disorder
Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics

SMARCB1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.89).

Transcripts

RefSeq

Gene	Transcript	HGVSc	Effect	Exon rank	MANE	Protein	UniProt
SMARCB1	NM_003073.5 link	c.500+114A>C	intron_variant	Intron 4 of 8	ENST00000644036.2	NP_003064.2	Q12824-1
SMARCB1	NM_001362877.2 link	c.554+60A>C	intron_variant	Intron 4 of 8		NP_001349806.1
SMARCB1	NM_001317946.2 link	c.527+60A>C	intron_variant	Intron 4 of 8		NP_001304875.1	G5E975Q9H836
SMARCB1	NM_001007468.3 link	c.473+114A>C	intron_variant	Intron 4 of 8		NP_001007469.1	Q12824-2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMARCB1	ENST00000644036.2 link	c.500+114A>C		intron_variant	Intron 4 of 8		NM_003073.5	ENSP00000494049.2		Q12824-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

7.86e-7

AC:

AN:

1272212

Hom.:

Cov.:

AF XY:

0.00000156

AC XY:

AN XY:

639642

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

29654

American (AMR)

AF:

0.00

AC:

AN:

40274

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

24614

East Asian (EAS)

AF:

0.00

AC:

AN:

37692

South Asian (SAS)

AF:

0.00

AC:

AN:

80282

European-Finnish (FIN)

AF:

0.00

AC:

AN:

51668

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5434

European-Non Finnish (NFE)

AF:

0.00000105

AC:

AN:

948520

Other (OTH)

AF:

0.00

AC:

AN:

54074

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.275

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.89

CADD

Benign

2.0

(source)

DANN

Benign

0.39

PhyloP100

0.13

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over