13-23340880-A-C

Variant names:

• chr13-23340880-A-C
• NM_014363.6:c.2996T>G

Variant summary

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

The NM_014363.6(SACS):​c.2996T>G​(p.Ile999Ser) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: SACS NM_014363.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.98

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]

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 rank	MANE	Protein	UniProt
SACS	NM_014363.6	c.2996T>G	p.Ile999Ser	missense_variant	Exon 10 of 10	ENST00000382292.9	NP_055178.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SACS	ENST00000382292.9	c.2996T>G	p.Ile999Ser	missense_variant	Exon 10 of 10	5	NM_014363.6	ENSP00000371729.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 36

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Spastic paraplegia Uncertain:1

Sep 01, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces isoleucine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 999 of the SACS protein (p.Ile999Ser). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SACS-related conditions. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt SACS protein function. 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	Benign	0.30
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.15
CADD	Benign	21
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.71	.;D
Eigen	Benign	-0.061
Eigen_PC	Benign	0.096
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Benign	0.83	T;T
M_CAP	Uncertain	0.16	D
MetaRNN	Uncertain	0.57	D;D
MetaSVM	Uncertain	-0.021	T
MutationAssessor	Uncertain	2.4	.;M
PrimateAI	Benign	0.36	T
PROVEAN	Uncertain	-3.4	D;D
REVEL	Pathogenic	0.73
Sift	Uncertain	0.0010	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		0.017	.;B
Vest4		0.42
MutPred		0.73		.;Loss of helix (P = 0.0041);
MVP		0.83
ClinPred		0.96	D
GERP RS		6.0
Varity_R		0.46
gMVP		0.85

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr13-23915019;