rs1555255676

Variant names:

• chr13-23368485-G-A
• rs1555255676
• NM_014363.6:c.262C>T

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The ENST00000382292.9(SACS):​c.262C>T​(p.Arg88*) variant causes a stop gained, splice region change. The variant allele was found at a frequency of 0.00000274 in 1,458,998 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. R88R) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: SACS ENST00000382292.9 stop_gained, splice_region
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 5.75
• Publications: 1 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 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-23368485-G-A is Pathogenic according to our data. Variant chr13-23368485-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 559870.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: ENST00000382292.9. 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.262C>T	p.Arg88*	stop_gained splice_region	Exon 5 of 10	NP_055178.3
	SACS	NM_001278055.2		c.-180C>T		5_prime_UTR_premature_start_codon_gain	Exon 3 of 8	NP_001264984.1
	SACS	NM_001437336.1		c.262C>T	p.Arg88*	stop_gained splice_region	Exon 5 of 11	NP_001424265.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SACS	ENST00000382292.9	TSL:5 MANE Select	c.262C>T	p.Arg88*	stop_gained splice_region	Exon 5 of 10	ENSP00000371729.3
	SACS	ENST00000455470.6	TSL:1	c.262C>T	p.Arg88*	stop_gained splice_region	Exon 5 of 11	ENSP00000406565.2
	SACS	ENST00000402364.1	TSL:2	c.-1989C>T		5_prime_UTR_premature_start_codon_gain	Exon 3 of 8	ENSP00000385844.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1458998 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 725618

African (AFR) AF: 0.00 AC: 0 AN: 33436

American (AMR) AF: 0.00 AC: 0 AN: 44500

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25990

East Asian (EAS) AF: 0.00 AC: 0 AN: 39676

South Asian (SAS) AF: 0.00 AC: 0 AN: 85724

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53336

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00000360 AC: 4 AN: 1110270

Other (OTH) AF: 0.00 AC: 0 AN: 60300

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions as Germline

Significance: Pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
2	-	-	Charlevoix-Saguenay spastic ataxia (2)
2	-	-	not provided (2)
1	-	-	Charcot-Marie-Tooth disease X-linked dominant 1 (1)
1	-	-	Spastic paraplegia (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.51
CADD	Pathogenic	40
DANN	Uncertain	1.0
Eigen	Uncertain	0.64
Eigen_PC	Uncertain	0.46
FATHMM_MKL	Uncertain	0.95	D
PhyloP100		5.7
Vest4		0.77
GERP RS		4.7
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: rs1555255676; hg19: chr13-23942624; COSMIC: COSV66534636; COSMIC: COSV66534636;