rs1236854134

Variant names:

• chr6-129320535-T-C
• rs1236854134
• NM_000426.4:c.4059-3T>C

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_000426.4(LAMA2):​c.4059-3T>C variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,210 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: LAMA2 NM_000426.4 splice_region, intron
• Scores: Splicing: ADA: 0.0001103
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.941
• Publications: 0 publications found

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]

LAMA2 Gene-Disease associations (from GenCC):

• congenital merosin-deficient muscular dystrophy 1A

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), Myriad Women’s Health, G2P
• LAMA2-related muscular dystrophy

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• muscular dystrophy, limb-girdle, autosomal recessive 23

  Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.6).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
LAMA2	NM_000426.4	c.4059-3T>C		splice_region_variant, intron_variant	Intron 27 of 64	ENST00000421865.3	NP_000417.3
LAMA2	NM_001079823.2	c.4059-3T>C		splice_region_variant, intron_variant	Intron 27 of 63		NP_001073291.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
LAMA2	ENST00000421865.3	c.4059-3T>C		splice_region_variant, intron_variant	Intron 27 of 64	5	NM_000426.4	ENSP00000400365.2
LAMA2	ENST00000618192.5	c.4323-3T>C		splice_region_variant, intron_variant	Intron 28 of 65	5		ENSP00000480802.2
LAMA2	ENST00000617695.5	c.4059-3T>C		splice_region_variant, intron_variant	Intron 27 of 63	5		ENSP00000481744.2

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152210 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 25

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152210 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74360

African (AFR) AF: 0.0000241 AC: 1 AN: 41446

American (AMR) AF: 0.00 AC: 0 AN: 15286

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5202

South Asian (SAS) AF: 0.00 AC: 0 AN: 4830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10626

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68028

Other (OTH) AF: 0.00 AC: 0 AN: 2092

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

LAMA2-related muscular dystrophy Uncertain:1

Jul 24, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Nucleotide substitutions within the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant is not likely to affect RNA splicing, but this prediction has not been confirmed by published transcriptional studies. This variant has not been reported in the literature in individuals with LAMA2-related disease. ClinVar contains an entry for this variant (Variation ID: 543881). This variant is not present in population databases (ExAC no frequency). This sequence change falls in intron 27 of the LAMA2 gene. It does not directly change the encoded amino acid sequence of the LAMA2 protein, but it affects a nucleotide within the consensus splice site of the intron. -

not provided Uncertain:1

Sep 17, 2019

Revvity Omics, Revvity

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.60
CADD	Benign	3.6
DANN	Benign	0.74
PhyloP100		0.94

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.00011
dbscSNV1_RF	Benign	0.0060
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: rs1236854134; hg19: chr6-129641680;