rs121913571

Positions:

• chr6-129516231-C-T

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_Strong PP5_Very_Strong

The NM_000426.4(LAMA2):​c.9253C>T​(p.Arg3085Ter) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000479 in 1,461,846 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 Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: LAMA2 NM_000426.4 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 3.37

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]

(HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 12 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.
• PP5: Variant 6-129516231-C-T is Pathogenic according to our data. Variant chr6-129516231-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 14291.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr6-129516231-C-T is described in Lovd as [Pathogenic]. Variant chr6-129516231-C-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
LAMA2	NM_000426.4	c.9253C>T	p.Arg3085Ter	stop_gained	65/65	ENST00000421865.3
LOC102723409	XR_001743860.2	n.12102+6246G>A		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
LAMA2	ENST00000421865.3	c.9253C>T	p.Arg3085Ter	stop_gained	65/65	5	NM_000426.4
	ENST00000665046.1	n.788+6246G>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251280 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135788

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: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1461846 Hom.: 0 Cov.: 32 AF XY: 0.00000688 AC XY: 5 AN XY: 727226

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: 0.0000187

Gnomad4 NFE exome AF: 0.00000540

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000756

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Merosin deficient congenital muscular dystrophy Pathogenic:3

Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 25, 2023	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Oct 09, 2001	- -
Likely pathogenic, no assertion criteria provided	clinical testing	Counsyl	Nov 15, 2017	- -

LAMA2-related muscular dystrophy Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Dec 18, 2023

This sequence change creates a premature translational stop signal (p.Arg3085*) in the LAMA2 gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 38 amino acid(s) of the LAMA2 protein. This variant is present in population databases (rs121913571, gnomAD 0.0009%). This premature translational stop signal has been observed in individual(s) with autosomal recessive congenital muscular dystrophy (PMID: 11591858, 34777456). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 14291). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Dec 20, 2022

Previously reported in a patient with congenital muscular dystrophy who had an abnormal merosin staining through immunohistochemistry and a second LAMA2 variant identified; however, parental testing was not reported (He et al., 2001); Not observed at significant frequency in large population cohorts (gnomAD); Nonsense variant predicted to result in protein truncation, as the last 38 amino acids are lost, and other loss-of-function variants have been reported downstream in HGMD; This variant is associated with the following publications: (PMID: 18937996, 27854218, 11591858, 34777456) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.51
CADD	Pathogenic	40
DANN	Uncertain	1.0
Eigen	Pathogenic	0.80
Eigen_PC	Uncertain	0.59
FATHMM_MKL	Uncertain	0.81	D
MutationTaster	Benign	1.0	A
Vest4		0.63
GERP RS		3.8

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.11		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: rs121913571; hg19: chr6-129837376;