rs775059063

chr13-23341435-CAT-C

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.2439_2440del(p.Val815GlyfsTer4) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000112 in 1,613,908 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: 𝑓 0.000039 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: SACS NM_014363.6 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:12
• Conservation: PhyloP100: 2.97

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 458 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-23341435-CAT-C is Pathogenic according to our data. Variant chr13-23341435-CAT-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 188856.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SACS	NM_014363.6	c.2439_2440del	p.Val815GlyfsTer4	frameshift_variant	10/10	ENST00000382292.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SACS	ENST00000382292.9	c.2439_2440del	p.Val815GlyfsTer4	frameshift_variant	10/10	5	NM_014363.6	P1

Frequencies

GnomAD3 genomes AF: 0.0000394 AC: 6 AN: 152186 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.000121

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000193

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251256 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135802

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461722 Hom.: 0 AF XY: 0.0000110 AC XY: 8 AN XY: 727168

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.0000188

Gnomad4 NFE exome AF: 0.00000719

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000394 AC: 6 AN: 152186 Hom.: 0 Cov.: 33 AF XY: 0.0000404 AC XY: 3 AN XY: 74338

Gnomad4 AFR AF: 0.000121

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000193

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000453

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:12

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Charlevoix-Saguenay spastic ataxia Pathogenic:7

Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Jan 07, 2021	- -
Likely pathogenic, criteria provided, single submitter	literature only	Counsyl	Jun 27, 2014	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 05, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 18, 2023	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Sep 28, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Institute of Human Genetics, Heidelberg University	Mar 23, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	Medical Genetics Laboratory, Tarbiat Modares University	Mar 01, 2020	- -

not provided Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen	Oct 23, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	Athena Diagnostics	Jul 08, 2019	The variant results in a shift of the reading frame, and is therefore predicted to result in the loss of a functional protein. Found in at least one symptomatic patient, and found in general population data that is consistent with pathogenicity. -
Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Dec 07, 2022	Frameshift variant predicted to result in protein truncation, as the last 3765 amino acids are replaced with 3 different amino acids, and other loss-of-function variants have been reported downstream in the Human Gene Mutation Database (HGMD); Not observed at a significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 23043354, 31429931, 35303589) -

Spastic paraplegia Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Sep 09, 2022

This sequence change creates a premature translational stop signal (p.Val815Glyfs*4) in the SACS gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 3765 amino acid(s) of the SACS protein. This variant is present in population databases (rs775059063, gnomAD 0.008%). This premature translational stop signal has been observed in individual(s) with spastic ataxia of Charlevoix-Saguenay (PMID: 23043354). ClinVar contains an entry for this variant (Variation ID: 188856). This variant disrupts a region of the SACS protein in which other variant(s) (p.Leu4303*, p.Arg3903*) have been determined to be pathogenic (PMID: 19892370, 21745802; Invitae). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Abnormal central motor function Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Kariminejad - Najmabadi Pathology & Genetics Center

Jul 10, 2021

- -

Computational scores

Source: dbNSFP v4.3

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: rs775059063; hg19: chr13-23915574; COSMIC: COSV66540773;