rs775112258

Positions:

• chr6-129328299-C-T

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PVS1 PP5_Very_Strong

The NM_000426.4(LAMA2):​c.4198C>T​(p.Arg1400*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000616 in 1,461,804 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 (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: LAMA2 NM_000426.4 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 3.21

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 Pathogenic. Variant got 16 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PP5: Variant 6-129328299-C-T is Pathogenic according to our data. Variant chr6-129328299-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 557566.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr6-129328299-C-T is described in Lovd as [Likely_pathogenic]. Variant chr6-129328299-C-T is described in Lovd as [Pathogenic]. Variant chr6-129328299-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
LAMA2	NM_000426.4	c.4198C>T	p.Arg1400*	stop_gained	29/65	ENST00000421865.3	NP_000417.3
LAMA2	NM_001079823.2	c.4198C>T	p.Arg1400*	stop_gained	29/64		NP_001073291.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
LAMA2	ENST00000421865.3	c.4198C>T	p.Arg1400*	stop_gained	29/65	5	NM_000426.4	ENSP00000400365.2
LAMA2	ENST00000618192.5	c.4462C>T	p.Arg1488*	stop_gained	30/66	5		ENSP00000480802.2
LAMA2	ENST00000617695.5	c.4198C>T	p.Arg1400*	stop_gained	29/64	5		ENSP00000481744.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251330 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135844

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: 0.00

Gnomad OTH exome AF: 0.000163

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1461804 Hom.: 0 Cov.: 32 AF XY: 0.00000688 AC XY: 5 AN XY: 727206

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000630

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

TwinsUK AF: 0.00 AC: 0

ALSPAC AF: 0.000519 AC: 2

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Oct 01, 2024	LAMA2: PVS1, PM3:Strong, PM2 -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Aug 14, 2023	Nonsense 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); This variant is associated with the following publications: (PMID: 31589614, 26039597, 24225367, 35924034, 37415604, 31069529) -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Feb 06, 2020	- -

Merosin deficient congenital muscular dystrophy Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 20, 2024	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Apr 04, 2018	- -

LAMA2-related muscular dystrophy Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 04, 2024

This sequence change creates a premature translational stop signal (p.Arg1400*) 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 (rs775112258, gnomAD 0.003%). This premature translational stop signal has been observed in individuals with congenital muscular dystrophy (PMID: 24225367). ClinVar contains an entry for this variant (Variation ID: 557566). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	40
DANN	Uncertain	1.0
Eigen	Pathogenic	0.73
Eigen_PC	Uncertain	0.60
FATHMM_MKL	Uncertain	0.86	D
Vest4		0.92
GERP RS		4.2

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: rs775112258; hg19: chr6-129649444; COSMIC: COSV70350217;