18-23873194-T-TG

Variant names:

• chr18-23873194-T-TG
• rs80356678
• NM_000227.6:c.151dupG

Variant summary

Our verdict is Pathogenic. The variant received 22 ACMG points: 22P and 0B. PVS1 PS3 PM2 PP5_Very_Strong

The NM_000227.6(LAMA3):​c.151dupG​(p.Val51GlyfsTer4) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000867 in 1,614,094 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV001361867: The variant, c.151dupG, has been reported in the literature in several homozygous, and at least one compound heterozygous individual affected with Laryngoonychocutaneous (or Shabbir) syndrome (McLean_2003). These data indicate that the variant is very likely to be associated with disease. This publication also reported experimental evidence evaluating an impact on protein function, and demonstrated that the variant caused a frameshift with a predicted stop codon in an exon that is specific to the laminin alpha-3a isoform, however did not result in nonsense-mediated mRNA decay due to rescue of the transcript by an alternative translation start site downstream, thus resulting in an N-terminal truncation of the laminin alpha-3a protein. The altered protein was demonstrated to be present in normal amount in patient derived skin biopsy material, however decreased cell-stromal junctions with reduced numbers of anchoring filaments were detected that is consistent with mechanism of the disease (McLean_2003)." and additional evidence is available in ClinVar. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: LAMA3 NM_000227.6 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 0.0440
• Publications: 4 publications found

Genes affected

LAMA3 (HGNC:6483): (laminin subunit alpha 3) The protein encoded by this gene belongs to the laminin family of secreted molecules. Laminins are heterotrimeric molecules that consist of alpha, beta, and gamma subunits that assemble through a coiled-coil domain. Laminins are essential for formation and function of the basement membrane and have additional functions in regulating cell migration and mechanical signal transduction. This gene encodes an alpha subunit and is responsive to several epithelial-mesenchymal regulators including keratinocyte growth factor, epidermal growth factor and insulin-like growth factor. Mutations in this gene have been identified as the cause of Herlitz type junctional epidermolysis bullosa and laryngoonychocutaneous syndrome. Alternative splicing and alternative promoter usage result in multiple transcript variants. [provided by RefSeq, Dec 2014]

LAMA3 Gene-Disease associations (from GenCC):

• junctional epidermolysis bullosa

  Inheritance: AR Classification: DEFINITIVE Submitted by: Myriad Women’s Health
• laryngo-onycho-cutaneous syndrome

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), G2P, Genomics England PanelApp
• junctional epidermolysis bullosa Herlitz type

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Orphanet
• junctional epidermolysis bullosa, non-Herlitz type

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp
• generalized junctional epidermolysis bullosa non-Herlitz type

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 22 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PS3: PS3 evidence extracted from ClinVar submissions: SCV001361867: The variant, c.151dupG, has been reported in the literature in several homozygous, and at least one compound heterozygous individual affected with Laryngoonychocutaneous (or Shabbir) syndrome (McLean_2003). These data indicate that the variant is very likely to be associated with disease. This publication also reported experimental evidence evaluating an impact on protein function, and demonstrated that the variant caused a frameshift with a predicted stop codon in an exon that is specific to the laminin alpha-3a isoform, however did not result in nonsense-mediated mRNA decay due to rescue of the transcript by an alternative translation start site downstream, thus resulting in an N-terminal truncation of the laminin alpha-3a protein. The altered protein was demonstrated to be present in normal amount in patient derived skin biopsy material, however decreased cell-stromal junctions with reduced numbers of anchoring filaments were detected that is consistent with mechanism of the disease (McLean_2003).; SCV002318758: Functional studies provide strong evidence of the variant having a damaging effect on the gene or gene product (PMID: 12915477).
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 18-23873194-T-TG is Pathogenic according to our data. Variant chr18-23873194-T-TG is described in ClinVar as Pathogenic. ClinVar VariationId is 42049.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000227.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	LAMA3	NM_000227.6	MANE Plus Clinical	c.151dupG	p.Val51GlyfsTer4	frameshift	Exon 1 of 38	NP_000218.3
	LAMA3	NM_198129.4	MANE Select	c.4998+1534dupG		intron	N/A	NP_937762.2	Q16787-2
	LAMA3	NM_001127718.4		c.151dupG	p.Val51GlyfsTer4	frameshift	Exon 1 of 37	NP_001121190.2	A0A0A0MTS5

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	LAMA3	ENST00000269217.11	TSL:1 MANE Plus Clinical	c.151dupG	p.Val51GlyfsTer4	frameshift	Exon 1 of 38	ENSP00000269217.5	Q16787-1
	LAMA3	ENST00000587184.5	TSL:1	c.151dupG	p.Val51GlyfsTer4	frameshift	Exon 1 of 37	ENSP00000466557.1	Q16787-4
	LAMA3	ENST00000313654.14	TSL:1 MANE Select	c.4998+1534dupG		intron	N/A	ENSP00000324532.8	Q16787-2

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152220 Hom.: 0 Cov.: 32

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: 0.000414

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000159 AC: 4 AN: 251494 AF XY: 0.0000221

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461874 Hom.: 0 Cov.: 31 AF XY: 0.0000151 AC XY: 11 AN XY: 727236

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.000139 AC: 12 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111996

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152220 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74368

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

African (AFR) AF: 0.00 AC: 0 AN: 41464

American (AMR) AF: 0.00 AC: 0 AN: 15284

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5196

South Asian (SAS) AF: 0.000414 AC: 2 AN: 4830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10618

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68038

Other (OTH) AF: 0.00 AC: 0 AN: 2090

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
3	-	-	Laryngo-onycho-cutaneous syndrome (3)
1	-	-	Junctional epidermolysis bullosa gravis of Herlitz (1)
1	-	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.044
Mutation Taster		=7/193	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs80356678; hg19: chr18-21453158;