13-23335031-TA-T

Variant names:

• chr13-23335031-TA-T
• rs281865117
• NM_014363.6:c.8844delT

Variant summary

Our verdict is Pathogenic. The variant received 22 ACMG points: 22P and 0B. PVS1 PS3 PM2 PP5_Very_Strong

The NM_014363.6(SACS):​c.8844delT​(p.Ile2949PhefsTer4) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000291 in 1,613,368 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV000918180: The lack of the of sacsin protein was confirmed by Western blott performed on immortalized lymphoblasts extracted from homozygous carriers." and additional evidence is available in ClinVar. Synonymous variant affecting the same amino acid position (i.e. P2948P) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000031 (0 hom.)
• Consequence: SACS NM_014363.6 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:14 O:1
• Conservation: PhyloP100: -0.680
• Publications: 14 publications found

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 Gene-Disease associations (from GenCC):

• Charlevoix-Saguenay spastic ataxia

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Laboratory for Molecular Medicine, PanelApp Australia, G2P, Myriad Women’s Health, Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 22 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 320 pathogenic variants in the truncated region.
• PS3: PS3 evidence extracted from ClinVar submissions: SCV000918180: The lack of the of sacsin protein was confirmed by Western blott performed on immortalized lymphoblasts extracted from homozygous carriers.; SCV000552973: Experimental studies have shown that this premature translational stop signal affects SACS function (PMID: 22307627).
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-23335031-TA-T is Pathogenic according to our data. Variant chr13-23335031-TA-T is described in ClinVar as Pathogenic. ClinVar VariationId is 5512.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_014363.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SACS	NM_014363.6	MANE Select	c.8844delT	p.Ile2949PhefsTer4	frameshift	Exon 10 of 10	NP_055178.3
	SACS	NM_001437336.1		c.8871delT	p.Ile2958PhefsTer4	frameshift	Exon 11 of 11	NP_001424265.1	A0A804HIQ1
	SACS	NM_001278055.2		c.8403delT	p.Ile2802PhefsTer4	frameshift	Exon 8 of 8	NP_001264984.1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SACS	ENST00000382292.9	TSL:5 MANE Select	c.8844delT	p.Ile2949PhefsTer4	frameshift	Exon 10 of 10	ENSP00000371729.3	Q9NZJ4-1
	SACS	ENST00000455470.6	TSL:1	c.2432-5548delT		intron	N/A	ENSP00000406565.2	H0Y6M8
	SACS	ENST00000682944.1		c.8871delT	p.Ile2958PhefsTer4	frameshift	Exon 11 of 11	ENSP00000507173.1	A0A804HIQ1

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152180 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000638 AC: 16 AN: 250832 AF XY: 0.0000590

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000290

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000132

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000308 AC: 45 AN: 1461188 Hom.: 0 Cov.: 37 AF XY: 0.0000330 AC XY: 24 AN XY: 726850

African (AFR) AF: 0.00 AC: 0 AN: 33422

American (AMR) AF: 0.0000224 AC: 1 AN: 44698

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26092

East Asian (EAS) AF: 0.00 AC: 0 AN: 39692

South Asian (SAS) AF: 0.00 AC: 0 AN: 86220

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53386

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 0.0000378 AC: 42 AN: 1111542

Other (OTH) AF: 0.0000331 AC: 2 AN: 60374

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152180 Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2 AN XY: 74356

African (AFR) AF: 0.00 AC: 0 AN: 41442

American (AMR) AF: 0.00 AC: 0 AN: 15280

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5202

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10626

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000294 AC: 2 AN: 68010

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.000174 Hom.: 0

Bravo AF: 0.0000113

EpiCase AF: 0.00

EpiControl AF: 0.000356

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
9	-	-	Charlevoix-Saguenay spastic ataxia (10)
2	-	-	not provided (2)
1	-	-	Hereditary spastic paraplegia (1)
1	-	-	SACS-related disorder (1)
1	-	-	Spastic paraplegia (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		-0.68
Mutation Taster		=0/200	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs281865117; hg19: chr13-23909170;