Genetic Variant SGCA:p.Glu146* (chr17-50168424-G-T) – ACMG Classification: Pathogenic (10 pts)

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1PM2

The NM_000023.4(SGCA):c.436G>T(p.Glu146*) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000695 in 1,439,490 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. E146E) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.9e-7 ( 0 hom. )

Consequence

SGCA
NM_000023.4 stop_gained

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 8.69

Publications

0 publications found

Variant links:

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]

SGCA Gene-Disease associations (from GenCC):

autosomal recessive limb-girdle muscular dystrophy
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
autosomal recessive limb-girdle muscular dystrophy type 2D
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Myriad Women’s Health, Laboratory for Molecular Medicine, Orphanet

SGCA links:

ENSG00000253730 (HGNC:):

ENSG00000253730 links:

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ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 10 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;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SGCA	NM_000023.4 link	c.436G>T	p.Glu146*	stop_gained	Exon 5 of 10	ENST00000262018.8	NP_000014.1	Q16586-1A0A0S2Z4Q1
SGCA	NM_001135697.3 link	c.436G>T	p.Glu146*	stop_gained	Exon 5 of 8		NP_001129169.1	Q16586-2A0A0S2Z4P8
SGCA	NR_135553.2 link	n.472G>T		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 link	c.436G>T	p.Glu146*	stop_gained	Exon 5 of 10	1	NM_000023.4	ENSP00000262018.3		Q16586-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.95e-7

AC:

AN:

1439490

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

713762

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33228

American (AMR)

AF:

0.00

AC:

AN:

41300

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25626

East Asian (EAS)

AF:

0.0000257

AC:

AN:

38848

South Asian (SAS)

AF:

0.00

AC:

AN:

82620

European-Finnish (FIN)

AF:

0.00

AC:

AN:

51510

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5726

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1101180

Other (OTH)

AF:

0.00

AC:

AN:

59452

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.225

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.62

BayesDel_noAF

Pathogenic

0.65

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

Eigen

Pathogenic

1.0

Eigen_PC

Pathogenic

0.86

FATHMM_MKL

Pathogenic

0.99

PhyloP100

8.7

Vest4

0.78

GERP RS

4.5

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.060

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over