Genetic Variant SMARCA2:p.Ser16Ser (chr9-2029070-G-C) – ACMG Classification: Likely_benign (-3 pts)

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2BP4_StrongBP7

The NM_003070.5(SMARCA2):c.48G>C(p.Ser16Ser) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000708 in 1,412,278 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. Synonymous variant affecting the same amino acid position (i.e. S16S) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 7.1e-7 ( 0 hom. )

Consequence

SMARCA2
NM_003070.5 synonymous

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: -1.73

Publications

0 publications found

Variant links:

Genes affected

SMARCA2 (HGNC:11098): (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 2) The protein encoded by this gene is a member of the SWI/SNF family of proteins and is highly 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. Alternatively spliced transcript variants encoding different isoforms have been found for this gene, which contains a trinucleotide repeat (CAG) length polymorphism. [provided by RefSeq, Jan 2014]

SMARCA2 Gene-Disease associations (from GenCC):

intellectual disability-sparse hair-brachydactyly syndrome
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae), ClinGen

SMARCA2 links:

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ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -3 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.56).

BP7

Synonymous conserved (PhyloP=-1.73 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMARCA2	NM_003070.5 link	c.48G>C	p.Ser16Ser	synonymous_variant	Exon 2 of 34	ENST00000349721.8	NP_003061.3	P51531-1Q8N9Q1Q56A76
SMARCA2	NM_001289396.2 link	c.48G>C	p.Ser16Ser	synonymous_variant	Exon 2 of 34		NP_001276325.1	P51531-1Q8N9Q1B4DSC8
SMARCA2	NM_139045.4 link	c.48G>C	p.Ser16Ser	synonymous_variant	Exon 2 of 33		NP_620614.2	P51531-2Q8N9Q1Q56A76
SMARCA2	NM_001289397.2 link	c.48G>C	p.Ser16Ser	synonymous_variant	Exon 2 of 33		NP_001276326.1	P51531F6VDE0

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMARCA2	ENST00000349721.8 link	c.48G>C	p.Ser16Ser	synonymous_variant	Exon 2 of 34	5	NM_003070.5	ENSP00000265773.5		P51531-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

7.08e-7

AC:

AN:

1412278

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

698258

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:

32044

American (AMR)

AF:

0.00

AC:

AN:

37960

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25344

East Asian (EAS)

AF:

0.00

AC:

AN:

36736

South Asian (SAS)

AF:

0.00

AC:

AN:

80974

European-Finnish (FIN)

AF:

0.00

AC:

AN:

50018

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5390

European-Non Finnish (NFE)

AF:

9.21e-7

AC:

AN:

1085366

Other (OTH)

AF:

0.00

AC:

AN:

58446

⚠️ 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: 0.375

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.56

CADD

Benign

6.8

(source)

DANN

Benign

0.73

PhyloP100

-1.7

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

ClinVar

Computational scores

Splicing

Publications

Other links and lift over