rs281865118

Positions:

• chr13-23336372-G-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_014363.6(SACS):​c.7504C>T​(p.Arg2502Ter) variant causes a stop gained change. The variant allele was found at a frequency of 0.0000103 in 1,461,782 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000010 (0 hom.)
• Consequence: SACS NM_014363.6 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:11 O:1
• Conservation: PhyloP100: 4.43

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 Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. There are 66 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-23336372-G-A is Pathogenic according to our data. Variant chr13-23336372-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 5513.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr13-23336372-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SACS	NM_014363.6	c.7504C>T	p.Arg2502Ter	stop_gained	10/10	ENST00000382292.9	NP_055178.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SACS	ENST00000382292.9	c.7504C>T	p.Arg2502Ter	stop_gained	10/10	5	NM_014363.6	ENSP00000371729	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000199 AC: 5 AN: 251338 Hom.: 0 AF XY: 0.0000221 AC XY: 3 AN XY: 135832

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000352

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000103 AC: 15 AN: 1461782 Hom.: 0 Cov.: 37 AF XY: 0.00000963 AC XY: 7 AN XY: 727188

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: 0.0000126

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

Alfa AF: 0.0000111 Hom.: 0

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:11 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Charlevoix-Saguenay spastic ataxia Pathogenic:8 Other:1

Pathogenic, no assertion criteria provided	literature only	OMIM	Feb 01, 2000	- -
Pathogenic, criteria provided, single submitter	research	PROSPAX: an integrated multimodal progression chart in spastic ataxias, Center for Neurology; Hertie-Institute for Clinical Brain Research	Jan 01, 2022	- -
not provided, no classification provided	literature only	GeneReviews	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Feb 10, 2023	- -
Pathogenic, no assertion criteria provided	clinical testing	Molecular Genetics Laboratory, BC Children's and BC Women's Hospitals	Oct 25, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Medical Genetics Laboratory, Tarbiat Modares University	Mar 01, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 05, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Sep 03, 2015	- -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Nov 14, 2023	Variant summary: SACS c.7504C>T (p.Arg2502X) results in a premature termination codon, predicted to cause a truncation of the encoded protein, which is a commonly known mechanism for disease. While this variant is not expected to result in nonsense mediated decay, it is predicted to disrupt the last 2,078 amino acids of the protein. Variants downstream of this position have been classified as pathogenic by our laboratory. The variant allele was found at a frequency of 2e-05 in 251338 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.7504C>T has been reported in the literature in multiple individuals affected with Autosomal Recessive Spastic Ataxia Of Charlevoix-Saguenay (e.g., Engert_2000). These data indicate that the variant is very likely to be associated with disease. The following publication was ascertained in the context of this evaluation (PMID: 10655055). Seven submitters have reported clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Spastic paraplegia Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 06, 2023

This sequence change creates a premature translational stop signal (p.Arg2502*) in the SACS gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 2078 amino acid(s) of the SACS protein. This variant is present in population databases (rs281865118, gnomAD 0.006%). This premature translational stop signal has been observed in individuals with autosomal recessive spastic ataxia of Charlevoix-Saguenay (PMID: 10655055, 30901567). This variant is also known as g.5254C>T. ClinVar contains an entry for this variant (Variation ID: 5513). For these reasons, this variant has been classified as Pathogenic. -

Hereditary spastic paraplegia Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Genome Diagnostics Laboratory, The Hospital for Sick Children

Dec 12, 2016

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen

Oct 23, 2020

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.50
CADD	Pathogenic	39
DANN	Uncertain	1.0
Eigen	Uncertain	0.62
Eigen_PC	Uncertain	0.47
FATHMM_MKL	Uncertain	0.89	D
MutationTaster	Benign	1.0	D;D;D
Vest4		0.97
GERP RS		2.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.6

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: rs281865118; hg19: chr13-23910511;