17-50168424-G-C

Variant names:

• chr17-50168424-G-C
• rs1555568758
• NM_000023.4:c.436G>C

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_000023.4(SGCA):​c.436G>C​(p.Glu146Gln) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: SGCA NM_000023.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.69

Genes affected

SGCA (HGNC:10805): (sarcoglycan alpha) This gene encodes a component of the dystrophin-glycoprotein complex (DGC), which is critical to the stability of muscle fiber membranes and to the linking of the actin cytoskeleton to the extracellular matrix. Its expression is thought to be restricted to striated muscle. Mutations in this gene result in type 2D autosomal recessive limb-girdle muscular dystrophy. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a topological_domain Extracellular (size 266) in uniprot entity SGCA_HUMAN there are 108 pathogenic changes around while only 2 benign (98%) in NM_000023.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.969

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SGCA	NM_000023.4	c.436G>C	p.Glu146Gln	missense_variant	Exon 5 of 10	ENST00000262018.8	NP_000014.1
SGCA	NM_001135697.3	c.436G>C	p.Glu146Gln	missense_variant	Exon 5 of 8		NP_001129169.1
SGCA	NR_135553.2	n.472G>C		non_coding_transcript_exon_variant	Exon 5 of 9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SGCA	ENST00000262018.8	c.436G>C	p.Glu146Gln	missense_variant	Exon 5 of 10	1	NM_000023.4	ENSP00000262018.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1439490 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 713762

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Autosomal recessive limb-girdle muscular dystrophy type 2D Uncertain:1

Apr 24, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glutamic acid with glutamine at codon 146 of the SGCA protein (p.Glu146Gln). The glutamic acid residue is highly conserved and there is a small physicochemical difference between glutamic acid and glutamine. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a SGCA-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.43
BayesDel_addAF	Pathogenic	0.30	D
BayesDel_noAF	Pathogenic	0.20
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.91	.;D;D
Eigen	Pathogenic	0.71
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.83	T;T;T
M_CAP	Pathogenic	0.44	D
MetaRNN	Pathogenic	0.97	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.4	M;M;.
PrimateAI	Uncertain	0.62	T
PROVEAN	Benign	-2.0	N;N;N
REVEL	Pathogenic	0.89
Sift	Uncertain	0.0050	D;D;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;D;.
Vest4		0.79
MutPred		0.87		Loss of glycosylation at S151 (P = 0.0804);Loss of glycosylation at S151 (P = 0.0804);.;
MVP		0.98
MPC		1.1
ClinPred		0.99	D
GERP RS		4.5
Varity_R		0.39
gMVP		0.95

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs1555568758; hg19: chr17-48245785;