rs771046502

Positions:

• chr6-129401345-G-A
• chr6-129401345-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PP3_Strong PP5_Moderate

The NM_000426.4(LAMA2):​c.5562+5G>A variant causes a splice donor 5th base, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: LAMA2 NM_000426.4 splice_donor_5th_base, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 5.26

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• 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 6-129401345-G-A is Pathogenic according to our data. Variant chr6-129401345-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 968246.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr6-129401345-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
LAMA2	NM_000426.4	c.5562+5G>A		splice_donor_5th_base_variant, intron_variant		ENST00000421865.3	NP_000417.3
LAMA2	NM_001079823.2	c.5562+5G>A		splice_donor_5th_base_variant, intron_variant			NP_001073291.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
LAMA2	ENST00000421865.3	c.5562+5G>A		splice_donor_5th_base_variant, intron_variant		5	NM_000426.4	ENSP00000400365
LAMA2	ENST00000617695.5	c.5562+5G>A		splice_donor_5th_base_variant, intron_variant		5		ENSP00000481744
LAMA2	ENST00000618192.5	c.5826+5G>A		splice_donor_5th_base_variant, intron_variant		5		ENSP00000480802	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1378038 Hom.: 0 Cov.: 22 AF XY: 0.00 AC XY: 0 AN XY: 690296

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: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

LAMA2-related muscular dystrophy Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 04, 2023

This sequence change falls in intron 38 of the LAMA2 gene. It does not directly change the encoded amino acid sequence of the LAMA2 protein. RNA analysis indicates that this variant induces altered splicing and likely results in a shortened protein product. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with clinical features of LAMA2-related muscular dystrophy (PMID: 12552556; Invitae). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. This variant is also known as IVS37+5G>A. ClinVar contains an entry for this variant (Variation ID: 968246). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant results in skipping of exon 38, but is expected to preserve the integrity of the reading-frame (PMID: 12552556). This variant disrupts the c.5562+5 nucleotide in the LAMA2 gene. Other variant(s) that disrupt this nucleotide have been determined to be pathogenic (PMID: 9536098, 10611118, 12552556, 17576681, 20207543). This suggests that this nucleotide is clinically significant, and that variants that disrupt this position are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.38
CADD	Pathogenic	32
DANN	Benign	0.75

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.99
SpliceAI score (max)		0.92		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.86		Position offset: 6
DS_DL_spliceai		0.92		Position offset: -5

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

Publications

LitVar

Other links and lift over

dbSNP: rs771046502; hg19: chr6-129722490;