13-23339132-C-T

Variant names:

• chr13-23339132-C-T
• rs1160357920
• NM_014363.6:c.4744G>A

Variant summary

Our verdict is Pathogenic. The variant received 16 ACMG points: 16P and 0B. PM1 PM2 PM5 PP3_Moderate PP5_Very_Strong

The NM_014363.6(SACS):​c.4744G>A​(p.Asp1582Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000435 in 1,610,374 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D1582H) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: SACS NM_014363.6 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:9
• Conservation: PhyloP100: 7.57
• Publications: 3 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: Orphanet, G2P, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), Myriad Women’s Health

ACMG classification

Our verdict: Pathogenic. The variant received 16 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 3 uncertain in NM_014363.6
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr13-23339132-C-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2694696.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.907
• PP5: Variant 13-23339132-C-T is Pathogenic according to our data. Variant chr13-23339132-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 458265.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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SACS	NM_014363.6	MANE Select	c.4744G>A	p.Asp1582Asn	missense	Exon 10 of 10	NP_055178.3
	SACS	NM_001437336.1		c.4771G>A	p.Asp1591Asn	missense	Exon 11 of 11	NP_001424265.1
	SACS	NM_001278055.2		c.4303G>A	p.Asp1435Asn	missense	Exon 8 of 8	NP_001264984.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SACS	ENST00000382292.9	TSL:5 MANE Select	c.4744G>A	p.Asp1582Asn	missense	Exon 10 of 10	ENSP00000371729.3
	SACS	ENST00000455470.6	TSL:1	c.2431+2313G>A		intron	N/A	ENSP00000406565.2
	SACS	ENST00000682944.1		c.4771G>A	p.Asp1591Asn	missense	Exon 11 of 11	ENSP00000507173.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152092 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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000411 AC: 6 AN: 1458282 Hom.: 0 Cov.: 36 AF XY: 0.00000414 AC XY: 3 AN XY: 724892

African (AFR) AF: 0.00 AC: 0 AN: 33382

American (AMR) AF: 0.00 AC: 0 AN: 44488

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25964

East Asian (EAS) AF: 0.00 AC: 0 AN: 39642

South Asian (SAS) AF: 0.00 AC: 0 AN: 85734

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53290

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5752

European-Non Finnish (NFE) AF: 0.00000541 AC: 6 AN: 1109774

Other (OTH) AF: 0.00 AC: 0 AN: 60256

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152092 Hom.: 0 Cov.: 33 AF XY: 0.0000135 AC XY: 1 AN XY: 74284

African (AFR) AF: 0.00 AC: 0 AN: 41398

American (AMR) AF: 0.00 AC: 0 AN: 15272

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3464

East Asian (EAS) AF: 0.00 AC: 0 AN: 5196

South Asian (SAS) AF: 0.00 AC: 0 AN: 4824

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10598

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

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68020

Other (OTH) AF: 0.00 AC: 0 AN: 2092

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000151

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:9

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Charlevoix-Saguenay spastic ataxia Pathogenic:7

Oct 04, 2017

Counsyl

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com.

Sep 05, 2021

Genome-Nilou Lab

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Oct 31, 2018

Fulgent Genetics, Fulgent Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Apr 29, 2022

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: SACS c.4744G>A (p.Asp1582Asn) results in a conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 6.6e-06 in 150864 control chromosomes (gnomAD v3.1, genomes dataset). The variant, c.4744G>A, has been reported in the literature in multiple compound heterozygous individuals affected with typical Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS), who carried the French-Canadian founder mutation (c.8844delT (p.Ile2949PhefsX4)) in trans (Thiffault_2013, Briand_2019). Western blot analysis of lymphoblast samples from one of these patients demonstrated a severe decrease in sacsin protein amount (Thiffault_2013). In addition, the variant was also reported in homozygous form in two siblings who were diagnosed with isolated (non-syndromic) motor and sensory neuropathy (Vill_2018). These data indicate that the variant is very likely to be associated with disease. Six clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014, and all laboratories classified the variant as pathogenic/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic.

Nov 08, 2017

Institute of Human Genetics Munich, TUM University Hospital

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Mar 27, 2024

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Jan 01, 2022

PROSPAX: an integrated multimodal progression chart in spastic ataxias, Center for Neurology; Hertie-Institute for Clinical Brain Research

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

Spastic paraplegia Pathogenic:1

Jan 23, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces aspartic acid, which is acidic and polar, with asparagine, which is neutral and polar, at codon 1582 of the SACS protein (p.Asp1582Asn). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with autosomal recessive spastic ataxia of Charlevoix-Saguenay (PMID: 23250129). ClinVar contains an entry for this variant (Variation ID: 458265). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on SACS protein function. Studies have shown that this missense change alters SACS gene expression (PMID: 23250129). For these reasons, this variant has been classified as Pathogenic.

Hereditary spastic paraplegia Pathogenic:1

Dec 12, 2016

Genome Diagnostics Laboratory, The Hospital for Sick Children

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Uncertain	0.12	D
BayesDel_noAF	Uncertain	-0.070
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.68	D
Eigen	Uncertain	0.67
Eigen_PC	Uncertain	0.64
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.96	D
M_CAP	Pathogenic	0.53	D
MetaRNN	Pathogenic	0.91	D
MetaSVM	Uncertain	0.64	D
MutationAssessor	Uncertain	2.4	M
PhyloP100		7.6
PrimateAI	Pathogenic	0.84	D
PROVEAN	Pathogenic	-4.4	D
REVEL	Pathogenic	0.75
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.98
MutPred		0.55		Gain of catalytic residue at I1585 (P = 5e-04)
MVP		0.86
ClinPred		1.0	D
GERP RS		5.3
Varity_R		0.76
gMVP		0.93
Mutation Taster		=9/91	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: rs1160357920; hg19: chr13-23913271;