7-107923964-C-T

Position:

• chr7-107923964-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_002291.3(LAMB1):​c.5348G>A​(p.Ser1783Asn) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S1783G) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: LAMB1 NM_002291.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.62

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]

DLD (HGNC:2898): (dihydrolipoamide dehydrogenase) This gene encodes a member of the class-I pyridine nucleotide-disulfide oxidoreductase family. The encoded protein has been identified as a moonlighting protein based on its ability to perform mechanistically distinct functions. In homodimeric form, the encoded protein functions as a dehydrogenase and is found in several multi-enzyme complexes that regulate energy metabolism. However, as a monomer, this protein can function as a protease. Mutations in this gene have been identified in patients with E3-deficient maple syrup urine disease and lipoamide dehydrogenase deficiency. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2014]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.20989716).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
LAMB1	NM_002291.3	c.5348G>A	p.Ser1783Asn	missense_variant	34/34	ENST00000222399.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
LAMB1	ENST00000222399.11	c.5348G>A	p.Ser1783Asn	missense_variant	34/34	1	NM_002291.3	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 03, 2022

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces serine, which is neutral and polar, with asparagine, which is neutral and polar, at codon 1783 of the LAMB1 protein (p.Ser1783Asn). This variant has not been reported in the literature in individuals affected with LAMB1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.30
BayesDel_addAF	Benign	-0.016	T
BayesDel_noAF	Benign	-0.26
CADD	Benign	21
DANN	Benign	0.77
DEOGEN2	Benign	0.066	.;T
Eigen	Benign	0.019
Eigen_PC	Benign	0.17
FATHMM_MKL	Uncertain	0.86	D
LIST_S2	Uncertain	0.86	D;D
M_CAP	Benign	0.071	D
MetaRNN	Benign	0.21	T;T
MetaSVM	Uncertain	0.43	D
MutationAssessor	Benign	1.1	.;L
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.66	T
PROVEAN	Benign	-0.23	N;N
REVEL	Uncertain	0.32
Sift	Benign	0.78	T;T
Sift4G	Benign	0.60	T;T
Polyphen		1.0	D;B
Vest4		0.38
MutPred		0.31		Loss of disorder (P = 0.0842);.;
MVP		0.87
MPC		0.46
ClinPred		0.82	D
GERP RS		5.4
Varity_R		0.23
gMVP		0.26

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

Publications

LitVar

Other links and lift over

dbSNP: rs767997731; hg19: chr7-107564409;