NM_002291.3:c.462C>A

Variant names:

• chr7-107986325-G-T
• rs25659
• NM_002291.3:c.462C>A

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP7

The NM_002291.3(LAMB1):​c.462C>A​(p.Ser154Ser) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,456,218 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. S154S) has been classified as Benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: LAMB1 NM_002291.3 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -1.51
• Publications: 0 publications found

Genes affected

LAMB1 (HGNC:6486): (laminin subunit beta 1) 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 are composed of 3 non identical chains: laminin alpha, beta and gamma (formerly A, B1, and B2, respectively) and they form 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 beta chain isoform laminin, beta 1. The beta 1 chain has 7 structurally distinct domains which it shares with other beta chain isomers. The C-terminal helical region containing domains I and II are separated by domain alpha, domains III and V contain several EGF-like repeats, and domains IV and VI have a globular conformation. Laminin, beta 1 is expressed in most tissues that produce basement membranes, and is one of the 3 chains constituting laminin 1, the first laminin isolated from Engelbreth-Holm-Swarm (EHS) tumor. A sequence in the beta 1 chain that is involved in cell attachment, chemotaxis, and binding to the laminin receptor was identified and shown to have the capacity to inhibit metastasis. [provided by RefSeq, Aug 2011]

LAMB1 Gene-Disease associations (from GenCC):

• cobblestone lissencephaly without muscular or ocular involvement

  Inheritance: AR Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: ClinGen, Labcorp Genetics (formerly Invitae), Ambry Genetics, Orphanet, PanelApp Australia, Genomics England PanelApp, G2P

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.69).
• BP7: Synonymous conserved (PhyloP=-1.51 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
LAMB1	NM_002291.3	c.462C>A	p.Ser154Ser	synonymous_variant	Exon 6 of 34	ENST00000222399.11	NP_002282.2
LAMB1	XM_047420359.1	c.462C>A	p.Ser154Ser	synonymous_variant	Exon 6 of 28		XP_047276315.1
LAMB1	XM_047420360.1	c.462C>A	p.Ser154Ser	synonymous_variant	Exon 6 of 25		XP_047276316.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
LAMB1	ENST00000222399.11	c.462C>A	p.Ser154Ser	synonymous_variant	Exon 6 of 34	1	NM_002291.3	ENSP00000222399.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1456218 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 723120

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

African (AFR) AF: 0.00 AC: 0 AN: 33388

American (AMR) AF: 0.00 AC: 0 AN: 44518

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26068

East Asian (EAS) AF: 0.00 AC: 0 AN: 39562

South Asian (SAS) AF: 0.00 AC: 0 AN: 85802

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53382

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5748

European-Non Finnish (NFE) AF: 0.00000181 AC: 2 AN: 1107592

Other (OTH) AF: 0.00 AC: 0 AN: 60158

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.002339), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.69
CADD	Benign	1.1
DANN	Benign	0.67
PhyloP100		-1.5
RBP_binding_hub_radar		0.92
RBP_regulation_power_radar		2.6

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		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: rs25659; hg19: chr7-107626770;