20-33408520-C-G

Position:

• chr20-33408520-C-G

Variant summary

Our verdict is Likely benign. Variant got -4 ACMG points: 0P and 4B. BS2

The NM_003098.3(SNTA1):​c.1505G>C​(p.Gly502Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000547 in 1,461,516 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000055 (0 hom.)
• Consequence: SNTA1 NM_003098.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.60

Genes affected

SNTA1 (HGNC:11167): (syntrophin alpha 1) Syntrophins are cytoplasmic peripheral membrane scaffold proteins that are components of the dystrophin-associated protein complex. This gene is a member of the syntrophin gene family and encodes the most common syntrophin isoform found in cardiac tissues. The N-terminal PDZ domain of this syntrophin protein interacts with the C-terminus of the pore-forming alpha subunit (SCN5A) of the cardiac sodium channel Nav1.5. This protein also associates cardiac sodium channels with the nitric oxide synthase-PMCA4b (plasma membrane Ca-ATPase subtype 4b) complex in cardiomyocytes. This gene is a susceptibility locus for Long-QT syndrome (LQT) - an inherited disorder associated with sudden cardiac death from arrhythmia - and sudden infant death syndrome (SIDS). This protein also associates with dystrophin and dystrophin-related proteins at the neuromuscular junction and alters intracellular calcium ion levels in muscle tissue. [provided by RefSeq, Jan 2013]

LOC124904889 (HGNC:):

ACMG classification

Verdict is Likely_benign. Variant got -4 ACMG points.

• BS2: High AC in GnomAdExome4 at 8 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SNTA1	NM_003098.3	c.1505G>C	p.Gly502Ala	missense_variant	8/8	ENST00000217381.3	NP_003089.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SNTA1	ENST00000217381.3	c.1505G>C	p.Gly502Ala	missense_variant	8/8	1	NM_003098.3	ENSP00000217381.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000547 AC: 8 AN: 1461516 Hom.: 0 Cov.: 30 AF XY: 0.00000550 AC XY: 4 AN XY: 727086

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: 0.00000630

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Long QT syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 22, 2019

This sequence change replaces glycine with alanine at codon 502 of the SNTA1 protein (p.Gly502Ala). The glycine residue is highly conserved and there is a small physicochemical difference between glycine and alanine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with SNTA1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Uncertain	0.14	D
BayesDel_noAF	Uncertain	-0.040
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.72	D
Eigen	Benign	0.15
Eigen_PC	Benign	0.11
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Uncertain	0.15	D
MetaRNN	Uncertain	0.72	D
MetaSVM	Uncertain	-0.047	T
MutationAssessor	Uncertain	2.2	M
PrimateAI	Pathogenic	0.85	D
PROVEAN	Pathogenic	-5.0	D
REVEL	Uncertain	0.59
Sift	Uncertain	0.017	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.60
MutPred		0.48		Gain of relative solvent accessibility (P = 0.0522);
MVP		0.77
MPC		0.95
ClinPred		0.98	D
GERP RS		3.6
Varity_R		0.59
gMVP		0.62

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

LitVar

Other links and lift over

dbSNP: rs1989651824; hg19: chr20-31996326;