chr20-33439020-C-G

Position:

• chr20-33439020-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_003098.3(SNTA1):​c.317G>C​(p.Arg106Pro) variant causes a missense 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R106Q) has been classified as Benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: SNTA1 NM_003098.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.67

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SNTA1	NM_003098.3	c.317G>C	p.Arg106Pro	missense_variant	2/8	ENST00000217381.3	NP_003089.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SNTA1	ENST00000217381.3	c.317G>C	p.Arg106Pro	missense_variant	2/8	1	NM_003098.3	ENSP00000217381.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

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

Jul 25, 2022

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with proline, which is neutral and non-polar, at codon 106 of the SNTA1 protein (p.Arg106Pro). This variant has not been reported in the literature in individuals affected with SNTA1-related conditions. 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. 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: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). ClinVar contains an entry for this variant (Variation ID: 1000782). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Benign	-0.028	T
BayesDel_noAF	Benign	-0.28
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.44	T
Eigen	Uncertain	0.42
Eigen_PC	Uncertain	0.39
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Benign	0.68	T
M_CAP	Benign	0.023	T
MetaRNN	Uncertain	0.47	T
MetaSVM	Benign	-0.89	T
MutationAssessor	Benign	2.0	M
PrimateAI	Pathogenic	0.82	D
PROVEAN	Uncertain	-3.8	D
REVEL	Benign	0.24
Sift	Uncertain	0.0030	D
Sift4G	Uncertain	0.0090	D
Polyphen		0.44	B
Vest4		0.52
MutPred		0.58		Loss of MoRF binding (P = 0.0154);
MVP		0.46
MPC		1.1
ClinPred		0.97	D
GERP RS		4.0
Varity_R		0.73
gMVP		0.66

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: rs75025585; hg19: chr20-32026826;