rs780348174

chr13-23324457-CTG-C

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PVS1_Strong PM2 PP5_Very_Strong

The NM_000231.3(SGCG):c.800_801del(p.Cys267SerfsTer51) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,806 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: SGCG NM_000231.3 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 9.07

Genes affected

SGCG (HGNC:10809): (sarcoglycan gamma) This gene encodes gamma-sarcoglycan, one of several sarcolemmal transmembrane glycoproteins that interact with dystrophin. The dystrophin-glycoprotein complex (DGC) spans the sarcolemma and is comprised of dystrophin, syntrophin, alpha- and beta-dystroglycans and sarcoglycans. The DGC provides a structural link between the subsarcolemmal cytoskeleton and the extracellular matrix of muscle cells. Defects in the encoded protein can lead to early onset autosomal recessive muscular dystrophy, in particular limb-girdle muscular dystrophy, type 2C (LGMD2C). [provided by RefSeq, Oct 2008]

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 14 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 4 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-23324457-CTG-C is Pathogenic according to our data. Variant chr13-23324457-CTG-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 552513.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr13-23324457-CTG-C is described in Lovd as [Pathogenic]. Variant chr13-23324457-CTG-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SGCG	NM_000231.3	c.800_801del	p.Cys267SerfsTer51	frameshift_variant	8/8	ENST00000218867.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SGCG	ENST00000218867.4	c.800_801del	p.Cys267SerfsTer51	frameshift_variant	8/8	1	NM_000231.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000795 AC: 2 AN: 251472 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135916

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.0000992

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461806 Hom.: 0 AF XY: 0.00000413 AC XY: 3 AN XY: 727210

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.0000383

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Alfa AF: 0.000111 Hom.: 0

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Autosomal recessive limb-girdle muscular dystrophy type 2C Pathogenic:4

Pathogenic, no assertion criteria provided	literature only	OMIM	Nov 01, 1996	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Jun 13, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Apr 14, 2023	ClinVar contains an entry for this variant (Variation ID: 552513). This variant is also known as ∆801–TC. This frameshift has been observed in individual(s) with limb-girdle muscular dystrophy (PMID: 8923014, 24638197). This variant is present in population databases (rs780348174, gnomAD 0.01%). This sequence change results in a frameshift in the SGCG gene (p.Cys267Serfs*51). While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 25 amino acid(s) of the SGCG protein and extend the protein by 25 additional amino acid residues. For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Cys283 amino acid residue in SGCG. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 8968757, 22095924). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Aug 09, 2023	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

CeGaT Center for Human Genetics Tuebingen

Jun 01, 2020

- -

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: rs780348174; hg19: chr13-23898596;