3-49121291-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2 BP4

The NM_002292.4(LAMB2):c.5332G>C(p.Ala1778Pro) 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. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: LAMB2 NM_002292.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.01

Genes affected

LAMB2 (HGNC:6487): (laminin subunit beta 2) 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, composed of 3 non identical chains: laminin alpha, beta and gamma (formerly A, B1, and B2, respectively), 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 2. The beta 2 chain contains the 7 structural domains typical of beta chains of laminin, including the short alpha region. However, unlike beta 1 chain, beta 2 has a more restricted tissue distribution. It is enriched in the basement membrane of muscles at the neuromuscular junctions, kidney glomerulus and vascular smooth muscle. Transgenic mice in which the beta 2 chain gene was inactivated by homologous recombination, showed defects in the maturation of neuromuscular junctions and impairment of glomerular filtration. Alternative splicing involving a non consensus 5' splice site (gc) in the 5' UTR of this gene has been reported. It was suggested that inefficient splicing of this first intron, which does not change the protein sequence, results in a greater abundance of the unspliced form of the transcript than the spliced form. The full-length nature of the spliced transcript is not known. [provided by RefSeq, Aug 2011]

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.39638397).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
LAMB2	NM_002292.4	c.5332G>C	p.Ala1778Pro	missense_variant	32/32	ENST00000305544.9
LAMB2	XM_005265127.5	c.5332G>C	p.Ala1778Pro	missense_variant	33/33

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
LAMB2	ENST00000305544.9	c.5332G>C	p.Ala1778Pro	missense_variant	32/32	1	NM_002292.4	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

LAMB2-related infantile-onset nephrotic syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Neuberg Centre For Genomic Medicine, NCGM

-

The missense variant p.A1778P in LAMB2 (NM_002292.4) has not been reported previously as a pathogenic variant nor as a benign variant, to our knowledge. The p.A1778P variant is novel (not in any individuals) in gnomAD Exomes and is novel (not in any individuals) in 1000 Genomes. In silico tools are contradictory in their predictions (SIFT-tolerated, Polyphen-2 -Damaging) and the residue is conserved across species. For these reasons, this variant has been classified as Uncertain Significance. In the absence of another reportable variant the diagnosis of LAMB2 related recessive disorder is not confirmed. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.84
BayesDel_addAF	Benign	-0.049	T
BayesDel_noAF	Benign	-0.31
Cadd	Uncertain	24
Dann	Uncertain	1.0
DEOGEN2	Benign	0.18	T;T
Eigen	Uncertain	0.54
Eigen_PC	Uncertain	0.53
FATHMM_MKL	Uncertain	0.95	D
M_CAP	Benign	0.017	T
MetaRNN	Benign	0.40	T;T
MetaSVM	Benign	-0.97	T
MutationAssessor	Benign	1.4	L;L
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.67	T
PROVEAN	Benign	-1.7	N;N
REVEL	Benign	0.18
Sift	Benign	0.27	T;T
Sift4G	Benign	0.27	T;T
Polyphen		1.0	D;D
Vest4		0.53
MutPred		0.38		Loss of MoRF binding (P = 0.0542);Loss of MoRF binding (P = 0.0542);
MVP		0.39
MPC		1.9
ClinPred		0.91	D
GERP RS		4.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.64
gMVP		0.61

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr3-49158724;