rs886043693

Variant names:

• chr6-129098371-T-A
• rs886043693
• NM_000426.4:c.595T>A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PP3_Strong

The NM_000426.4(LAMA2):​c.595T>A​(p.Cys199Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000547 in 1,461,778 control chromosomes in the GnomAD database, with no homozygous occurrence. 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: 0.0000055 (0 hom.)
• Consequence: LAMA2 NM_000426.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 8.01

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a domain Laminin N-terminal (size 251) in uniprot entity LAMA2_HUMAN there are 14 pathogenic changes around while only 1 benign (93%) in NM_000426.4
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.985

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
LAMA2	NM_000426.4	c.595T>A	p.Cys199Ser	missense_variant	Exon 4 of 65	ENST00000421865.3	NP_000417.3
LAMA2	NM_001079823.2	c.595T>A	p.Cys199Ser	missense_variant	Exon 4 of 64		NP_001073291.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
LAMA2	ENST00000421865.3	c.595T>A	p.Cys199Ser	missense_variant	Exon 4 of 65	5	NM_000426.4	ENSP00000400365.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251416 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135886

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 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: 0.00000547 AC: 8 AN: 1461778 Hom.: 0 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727202

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: 0.00000630

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Dec 12, 2023

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: LAMA2 c.595T>A (p.Cys199Ser) results in a non-conservative amino acid change located in the Laminin, N-terminal domain (IPR008211) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 251416 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.595T>A has been reported in the literature in the compound heterozygous state in at least one individual affected with Laminin Alpha 2-Related Dystrophy (e.g. Chan_2014, Sframeli_2017). These data do not allow any conclusion about variant significance. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 24957499, 28688748). Four submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Merosin deficient congenital muscular dystrophy Uncertain:1

Jan 24, 2018

Counsyl

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

LAMA2-related muscular dystrophy Uncertain:1

Apr 15, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces cysteine, which is neutral and slightly polar, with serine, which is neutral and polar, at codon 199 of the LAMA2 protein (p.Cys199Ser). This variant is present in population databases (no rsID available, gnomAD 0.0009%). This missense change has been observed in individual(s) with limb-girdle muscular dystrophy (PMID: 24957499). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 287678). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on LAMA2 protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

not provided Uncertain:1

Jun 09, 2016

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Congenital muscular dystrophy due to partial LAMA2 deficiency Uncertain:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. However, the evidence from the literature, in combination with allele frequency data from public databases where available, was not sufficient to rule this variant in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.42
CADD	Pathogenic	28
DANN	Uncertain	0.99
DEOGEN2	Benign	0.079	.;T;D
Eigen	Pathogenic	0.96
Eigen_PC	Pathogenic	0.87
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.89	D;D;D
M_CAP	Uncertain	0.23	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	0.94	D
MutationAssessor	Pathogenic	4.3	.;.;H
PrimateAI	Pathogenic	0.88	D
PROVEAN	Pathogenic	-9.4	.;.;D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	.;.;D
Polyphen		1.0	.;.;D
Vest4		0.97
MutPred		0.94		Gain of disorder (P = 0.0018);Gain of disorder (P = 0.0018);Gain of disorder (P = 0.0018);
MVP		0.92
MPC		0.53
ClinPred		1.0	D
GERP RS		5.3
Varity_R		0.98
gMVP		0.95

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: rs886043693; hg19: chr6-129419516;