rs201307156

Positions:

• chr1-183243203-C-T

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PVS1_Strong PM2 PP5_Very_Strong

The NM_005562.3(LAMC2):​c.3385C>T​(p.Arg1129*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000958 in 1,461,782 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 (★★). Synonymous variant affecting the same amino acid position (i.e. R1129R) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000096 (0 hom.)
• Consequence: LAMC2 NM_005562.3 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 0.787

Genes affected

LAMC2 (HGNC:6493): (laminin subunit gamma 2) Laminins, a family of extracellular matrix glycoproteins, are the major noncollagenous constituent of basement membranes. They have been implicated in a wide variety of biological processes including cell adhesion, differentiation, migration, signaling, neurite outgrowth and metastasis. Laminins, composed of 3 non identical chains: laminin alpha, beta and gamma (formerly A, B1, and B2, respectively), have a cruciform structure consisting of 3 short arms, each formed by a different chain, and a long arm composed of all 3 chains. Each laminin chain is a multidomain protein encoded by a distinct gene. Several isoforms of each chain have been described. Different alpha, beta and gamma chain isomers combine to give rise to different heterotrimeric laminin isoforms which are designated by Arabic numerals in the order of their discovery, i.e. alpha1beta1gamma1 heterotrimer is laminin 1. The biological functions of the different chains and trimer molecules are largely unknown, but some of the chains have been shown to differ with respect to their tissue distribution, presumably reflecting diverse functions in vivo. This gene encodes the gamma chain isoform laminin, gamma 2. The gamma 2 chain, formerly thought to be a truncated version of beta chain (B2t), is highly homologous to the gamma 1 chain; however, it lacks domain VI, and domains V, IV and III are shorter. It is expressed in several fetal tissues but differently from gamma 1, and is specifically localized to epithelial cells in skin, lung and kidney. The gamma 2 chain together with alpha 3 and beta 3 chains constitute laminin 5 (earlier known as kalinin), which is an integral part of the anchoring filaments that connect epithelial cells to the underlying basement membrane. The epithelium-specific expression of the gamma 2 chain implied its role as an epithelium attachment molecule, and mutations in this gene have been associated with junctional epidermolysis bullosa, a skin disease characterized by blisters due to disruption of the epidermal-dermal junction. Two transcript variants resulting from alternative splicing of the 3' terminal exon, and encoding different isoforms of gamma 2 chain, have been described. The two variants are differentially expressed in embryonic tissues, however, the biological significance of the two forms is not known. Transcript variants utilizing alternative polyA_signal have also been noted in literature. [provided by RefSeq, Aug 2011]

ACMG classification

Verdict is Pathogenic. Variant got 14 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.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-183243203-C-T is Pathogenic according to our data. Variant chr1-183243203-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 370953.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
LAMC2	NM_005562.3	c.3385C>T	p.Arg1129*	stop_gained	23/23	ENST00000264144.5	NP_005553.2
LAMC2	XM_047420358.1	c.3328+2812C>T		intron_variant			XP_047276314.1
LAMC2	XM_047420361.1	c.3328+2812C>T		intron_variant			XP_047276317.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
LAMC2	ENST00000264144.5	c.3385C>T	p.Arg1129*	stop_gained	23/23	1	NM_005562.3	ENSP00000264144.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251140 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135744

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: 0.00000881

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000958 AC: 14 AN: 1461782 Hom.: 0 Cov.: 31 AF XY: 0.00000825 AC XY: 6 AN XY: 727190

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 0.0000108

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ExAC AF: 0.0000165 AC: 2

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Junctional epidermolysis bullosa, non-Herlitz type Pathogenic:1

Pathogenic, no assertion criteria provided

research

Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine Ramathibodi Hospital, Mahidol University

Dec 08, 2020

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 29, 2024

This sequence change creates a premature translational stop signal (p.Arg1129*) in the LAMC2 gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 65 amino acid(s) of the LAMC2 protein. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This variant has not been reported in the literature in individuals affected with LAMC2-related conditions. ClinVar contains an entry for this variant (Variation ID: 370953). This variant disrupts a region of the LAMC2 protein in which other variant(s) (p.Thr1132Asnfs*38) have been determined to be pathogenic (PMID: 11564184). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Junctional epidermolysis bullosa gravis of Herlitz Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Counsyl

May 24, 2016

- -

Epidermolysis bullosa, junctional 3B, severe Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center

Dec 19, 2024

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.31
CADD	Pathogenic	37
DANN	Uncertain	0.99
Eigen	Uncertain	0.46
Eigen_PC	Uncertain	0.22
FATHMM_MKL	Benign	0.16	N
Vest4		0.64
ClinPred		0.98	D
GERP RS		3.0

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: rs201307156; hg19: chr1-183212338; COSMIC: COSV51454036; COSMIC: COSV51454036;