chr6-129315822-GGTTTCTCTACATATAATCCTCAA-G

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 16 ACMG points: 16P and 0B. PVS1PP5_Very_Strong

The NM_000426.4(LAMA2):c.3799_3821delTTCTCTACATATAATCCTCAAGT(p.Phe1267AspfsTer11) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000192 in 1,613,988 control chromosomes in the GnomAD database, with no homozygous occurrence. It is difficult to determine the true allele frequency of this variant because it is of type DEL_BIG, and the frequency of such variant types in population databases may be underestimated and unreliable. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000020 ( 0 hom. )

Consequence

LAMA2
NM_000426.4 frameshift

Scores

Not classified

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:6

Conservation

PhyloP100: 9.51

Publications

2 publications found

Variant links:

Genes affected

LAMA2 (HGNC:6482): (laminin subunit alpha 2) Laminin, an extracellular protein, is a major component of the basement membrane. It is thought to mediate the attachment, migration, and organization of cells into tissues during embryonic development by interacting with other extracellular matrix components. It is composed of three subunits, alpha, beta, and gamma, which are bound to each other by disulfide bonds into a cross-shaped molecule. This gene encodes the alpha 2 chain, which constitutes one of the subunits of laminin 2 (merosin) and laminin 4 (s-merosin). Mutations in this gene have been identified as the cause of congenital merosin-deficient muscular dystrophy. Two transcript variants encoding different proteins have been found for this gene. [provided by RefSeq, Jul 2008]

LAMA2 Gene-Disease associations (from GenCC):

congenital merosin-deficient muscular dystrophy 1A
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), Myriad Women’s Health, G2P
LAMA2-related muscular dystrophy
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
muscular dystrophy, limb-girdle, autosomal recessive 23
Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)

LAMA2 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 16 ACMG points.

PVS1

Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

PP5

Variant 6-129315822-GGTTTCTCTACATATAATCCTCAA-G is Pathogenic according to our data. Variant chr6-129315822-GGTTTCTCTACATATAATCCTCAA-G is described in ClinVar as Pathogenic. ClinVar VariationId is 280520.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
LAMA2	NM_000426.4 link	c.3799_3821delTTCTCTACATATAATCCTCAAGT	p.Phe1267AspfsTer11	frameshift_variant	Exon 26 of 65	ENST00000421865.3	NP_000417.3
LAMA2	NM_001079823.2 link	c.3799_3821delTTCTCTACATATAATCCTCAAGT	p.Phe1267AspfsTer11	frameshift_variant	Exon 26 of 64		NP_001073291.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein
LAMA2	ENST00000421865.3 link	c.3799_3821delTTCTCTACATATAATCCTCAAGT	p.Phe1267AspfsTer11	frameshift_variant	Exon 26 of 65	5	NM_000426.4	ENSP00000400365.2
LAMA2	ENST00000618192.5 link	c.4063_4085delTTCTCTACATATAATCCTCAAGT	p.Phe1355AspfsTer11	frameshift_variant	Exon 27 of 66	5		ENSP00000480802.2
LAMA2	ENST00000617695.5 link	c.3799_3821delTTCTCTACATATAATCCTCAAGT	p.Phe1267AspfsTer11	frameshift_variant	Exon 26 of 64	5		ENSP00000481744.2

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152198

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000294

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000159

AC:

AN:

251390

AF XY:

0.0000147

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000352

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000198

AC:

AN:

1461790

Hom.:

AF XY:

0.0000220

AC XY:

AN XY:

727198

show subpopulations

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

African (AFR)

AF:

0.0000299

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.0000383

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39698

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53346

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.0000243

AC:

AN:

1111990

Other (OTH)

AF:

0.00

AC:

AN:

60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.394

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

AF:

0.0000131

AC:

AN:

152198

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74352

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41448

American (AMR)

AF:

0.00

AC:

AN:

15276

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5196

South Asian (SAS)

AF:

0.00

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10618

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000294

AC:

AN:

68038

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.500

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.0000434

Hom.:

Bravo

AF:

0.0000151

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Merosin deficient congenital muscular dystrophy

Pathogenic:2

Oct 18, 2017

Counsyl

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Mar 03, 2024

Baylor Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not provided

Pathogenic:2

May 01, 2019

Revvity Omics, Revvity

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Apr 30, 2024

GeneDx

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Published functional studies demonstrate a damaging effect on LAMA2 expression, leading to complete absence of merosin on muscle staining (PMID: 17765811, 20207543); Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); Also known as p.V1274fsX11; This variant is associated with the following publications: (PMID: 17765811, 20207543, 30055037, 37476021) -

LAMA2-related muscular dystrophy

Pathogenic:1

Nov 30, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change creates a premature translational stop signal (p.Phe1267Aspfs*11) in the LAMA2 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in LAMA2 are known to be pathogenic (PMID: 18700894, 32904964). This variant is present in population databases (rs750220830, gnomAD 0.004%). This premature translational stop signal has been observed in individuals with merosin deficient congenital muscular dystrophy 1A (PMID: 20207543). ClinVar contains an entry for this variant (Variation ID: 280520). For these reasons, this variant has been classified as Pathogenic. -

Merosin deficient congenital muscular dystrophy;C4748327:Muscular dystrophy, limb-girdle, autosomal recessive 23

Pathogenic:1

May 27, 2024

Fulgent Genetics, Fulgent Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

9.5

Mutation Taster

=0/200

disease causing (ClinVar)

(source)

Splicing

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

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over