chr13-23355579-G-A

Variant names:

Variant summary

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

The NM_014363.6(SACS):c.1033C>T(p.Arg345Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000126 in 1,613,958 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.00011 ( 0 hom., cov: 33)

Exomes 𝑓: 0.00013 ( 0 hom. )

Consequence

SACS
NM_014363.6 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:6B:1

Conservation

PhyloP100: 3.00

Variant links:

Genes affected

SACS (HGNC:10519): (sacsin molecular chaperone) This gene encodes the sacsin protein, which includes a UbL domain at the N-terminus, a DnaJ domain, and a HEPN domain at the C-terminus. The gene is highly expressed in the central nervous system, also found in skin, skeletal muscles and at low levels in the pancreas. This gene includes a very large exon spanning more than 12.8 kb. Mutations in this gene result in autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS), a neurodegenerative disorder characterized by early-onset cerebellar ataxia with spasticity and peripheral neuropathy. The authors of a publication on the effects of siRNA-mediated sacsin knockdown concluded that sacsin protects against mutant ataxin-1 and suggest that "the large multi-domain sacsin protein is able to recruit Hsp70 chaperone action and has the potential to regulate the effects of other ataxia proteins" (Parfitt et al., PubMed: 19208651). A pseudogene associated with this gene is located on chromosome 11. Alternative splicing of this gene results in multiple transcript variants. [provided by RefSeq, May 2013]

SACS links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

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 rank	MANE	Protein	UniProt
SACS	NM_014363.6 link	c.1033C>T	p.Arg345Trp	missense_variant	Exon 8 of 10	ENST00000382292.9	NP_055178.3	Q9NZJ4-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SACS	ENST00000382292.9 link	c.1033C>T	p.Arg345Trp	missense_variant	Exon 8 of 10	5	NM_014363.6	ENSP00000371729.3		Q9NZJ4-1

Frequencies

GnomAD3 genomes

AF:

0.000105

AC:

AN:

152078

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000724

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000393

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000735

Gnomad OTH

AF:

0.000478

GnomAD3 exomes

AF:

0.0000597

AC:

AN:

251392

Hom.:

AF XY:

0.0000589

AC XY:

AN XY:

135866

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000867

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.000196

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000440

Gnomad OTH exome

AF:

0.000163

GnomAD4 exome

AF:

0.000128

AC:

187

AN:

1461880

Hom.:

Cov.:

AF XY:

0.000139

AC XY:

101

AN XY:

727242

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000894

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.000151

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.000151

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.000105

AC:

AN:

152078

Hom.:

Cov.:

AF XY:

0.0000942

AC XY:

AN XY:

74280

show subpopulations

Gnomad4 AFR

AF:

0.0000724

Gnomad4 AMR

AF:

0.000393

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.000207

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000735

Gnomad4 OTH

AF:

0.000478

Alfa

AF:

0.0000772

Hom.:

Bravo

AF:

0.000159

TwinsUK

AF:

0.000270

AC:

ALSPAC

AF:

0.00

AC:

ExAC

AF:

0.0000741

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:6Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Charlevoix-Saguenay spastic ataxia

Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 05, 2021	- -
Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -
Uncertain significance, criteria provided, single submitter	clinical testing	New York Genome Center	Sep 03, 2021	The c.1033C>T (p.Arg345Trp) variant identified in the SACS gene substitutes a well conserved Arginine for Tryptophan at amino acid 345/4580 (exon 8/10). This variant is found with low frequency in gnomAD(v3.1.1)(16 heterozygotes, 0 homozygotes; allele frequency: 1.05e-5) suggesting it is not a common benign variant in the populations represented in that database. In silico algorithms predict this variant to be Damaging (SIFT; score:0.001) and Pathogenic (REVEL;score:0.6349) to the function of the canonical transcript. This variant is reported as a Variant of Uncertain Significance in ClinVar (VarID:411689), and to our current knowledge has not been reported in affected individuals in the literature. The p.Arg345 residue is not within a mapped domain of SACS (UniProtKB:Q9NZJ4). Given the lack of compelling evidence for its pathogenicity, the c.1033C>T (p.Arg345Trp) variant identified in the SACS gene is reported as a Variant of Uncertain Significance. -

not specified

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Nov 29, 2024

Variant summary: SACS c.1033C>T (p.Arg345Trp) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 6e-05 in 251392 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in SACS causing Charlevoix-Saguenay spastic ataxia, allowing no conclusion about variant significance. To our knowledge, no occurrence of c.1033C>T in individuals affected with Charlevoix-Saguenay spastic ataxia and no experimental evidence demonstrating its impact on protein function have been reported. ClinVar contains an entry for this variant (Variation ID: 411689). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Inborn genetic diseases

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 26, 2023

The c.1033C>T (p.R345W) alteration is located in exon 8 (coding exon 7) of the SACS gene. This alteration results from a C to T substitution at nucleotide position 1033, causing the arginine (R) at amino acid position 345 to be replaced by a tryptophan (W). Based on data from gnomAD, the T allele has an overall frequency of 0.006% (15/251392) total alleles studied. The highest observed frequency was 0.02% (6/30612) of South Asian alleles. This amino acid position is well conserved in available vertebrate species. This alteration is predicted to be deleterious by in silico analysis. Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Jun 29, 2019

In silico analysis, which includes protein predictors and evolutionary conservation, supports that this variant does not alter protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Spastic paraplegia

Benign:1

Benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 15, 2024

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.19

BayesDel_addAF

Uncertain

0.068

BayesDel_noAF

Uncertain

0.13

CADD

Uncertain

DANN

Uncertain

1.0

DEOGEN2

Benign

0.20

T;.;.

Eigen

Uncertain

0.26

Eigen_PC

Benign

0.12

FATHMM_MKL

Uncertain

0.91

LIST_S2

Uncertain

0.97

D;D;D

M_CAP

Pathogenic

0.35

MetaRNN

Uncertain

0.57

D;D;D

MetaSVM

Uncertain

0.69

MutationAssessor

Uncertain

2.8

M;.;.

PrimateAI

Benign

0.45

PROVEAN

Benign

-1.2

N;.;.

REVEL

Uncertain

0.64

Sift

Uncertain

0.0010

D;.;.

Sift4G

Pathogenic

0.0010

D;.;.

Polyphen

0.96

D;.;.

Vest4

0.63

MutPred

0.50

Loss of disorder (P = 0.0109);Loss of disorder (P = 0.0109);Loss of disorder (P = 0.0109);

MVP

0.81

ClinPred

0.48

GERP RS

2.8

Varity_R

0.13

gMVP

0.80

Splicing

Name

Calibrated prediction

Score

Prediction

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over