rs1555254439

Variant names:

• chr13-23355780-G-A
• rs1555254439
• NM_014363.6:c.832C>T

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_014363.6(SACS):​c.832C>T​(p.Gln278*) variant causes a stop gained change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 33)
• Consequence: SACS NM_014363.6 stop_gained
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 4.04
• Publications: 0 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 12 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 13-23355780-G-A is Pathogenic according to our data. Variant chr13-23355780-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 551347.Status of the report is criteria_provided_single_submitter, 1 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.832C>T	p.Gln278*	stop_gained	Exon 8 of 10	NP_055178.3
	SACS	NM_001437336.1		c.832C>T	p.Gln278*	stop_gained	Exon 8 of 11	NP_001424265.1
	SACS	NM_001278055.2		c.391C>T	p.Gln131*	stop_gained	Exon 6 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.832C>T	p.Gln278*	stop_gained	Exon 8 of 10	ENSP00000371729.3
	SACS	ENST00000455470.6	TSL:1	c.832C>T	p.Gln278*	stop_gained	Exon 8 of 11	ENSP00000406565.2
	SACS	ENST00000682944.1		c.832C>T	p.Gln278*	stop_gained	Exon 8 of 11	ENSP00000507173.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions as Germline

Significance: Pathogenic

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
2	-	-	Charlevoix-Saguenay spastic ataxia (2)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.26
CADD	Pathogenic	35
DANN	Uncertain	1.0
Eigen	Pathogenic	0.69
Eigen_PC	Uncertain	0.43
FATHMM_MKL	Uncertain	0.86	D
PhyloP100		4.0
Vest4		0.89
ClinPred		0.98	D
GERP RS		3.8
Mutation Taster		=1/199	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: rs1555254439; hg19: chr13-23929919;