rs759555791

chr6-129288059-G-Achr6-129288059-G-C

Variant summary

Our verdict is Pathogenic. Variant got 20 ACMG points: 20P and 0B. PVS1 PP3_Strong PP5_Very_Strong

The NM_000426.4(LAMA2):c.2749+1G>A variant causes a splice donor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000616 in 1,460,502 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: LAMA2 NM_000426.4 splice_donor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 10.0

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 20 ACMG points.

• PVS1: Splicing variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 6-129288059-G-A is Pathogenic according to our data. Variant chr6-129288059-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 552629.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr6-129288059-G-A is described in Lovd as [Pathogenic]. Variant chr6-129288059-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
LAMA2	NM_000426.4	c.2749+1G>A		splice_donor_variant		ENST00000421865.3
LAMA2	NM_001079823.2	c.2749+1G>A		splice_donor_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
LAMA2	ENST00000421865.3	c.2749+1G>A		splice_donor_variant		5	NM_000426.4
LAMA2	ENST00000617695.5	c.2749+1G>A		splice_donor_variant		5
LAMA2	ENST00000618192.5	c.2749+1G>A		splice_donor_variant		5		P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250932 Hom.: 0 AF XY: 0.00000737 AC XY: 1 AN XY: 135612

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS 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: 0.00000616 AC: 9 AN: 1460502 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 726672

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000756

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000360

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Merosin deficient congenital muscular dystrophy Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 02, 2023	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Molecular Diagnostics Laboratory, M Health Fairview: University of Minnesota	Jan 16, 2017	- -

LAMA2-related muscular dystrophy Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Aug 07, 2023

Disruption of this splice site has been observed in individual(s) with clinical features of LAMA2-related muscular dystrophy (PMID: 21922472, 24225367). It has also been observed to segregate with disease in related individuals. This sequence change affects a donor splice site in intron 19 of the LAMA2 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in LAMA2 are known to be pathogenic (PMID: 18700894, 32904964). This variant is present in population databases (rs759555791, gnomAD 0.006%). ClinVar contains an entry for this variant (Variation ID: 552629). 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. -

Merosin deficient congenital muscular dystrophy;C4748327:Muscular dystrophy, limb-girdle, autosomal recessive 23 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Myriad Genetics, Inc.

Nov 08, 2021

NM_000426.3(LAMA2):c.2749+1G>A is a canonical splice variant classified as likely pathogenic in the context of muscular dystrophy, LAMA2-related. c.2749+1G>A has been observed in cases with relevant disease (PMID: 24225367, 21922472). Functional assessments of this variant are not available in the literature. c.2749+1G>A has been observed in population frequency databases (gnomAD: EAS 0.01%). In summary, NM_000426.3(LAMA2):c.2749+1G>A is a canonical splice variant in a gene where loss of function is a known mechanism of disease, is predicted to disrupt protein function, and has been observed more frequently in cases with the relevant disease than in healthy populations. Please note: this variant was assessed in the context of healthy population screening. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.41
Cadd	Pathogenic	34
Dann	Uncertain	1.0
Eigen	Pathogenic	1.3
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.99	D
MutationTaster	Benign	1.0	D
GERP RS		5.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_DL_spliceai		1.0		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs759555791; hg19: chr6-129609204;