1-183023936-G-C

Position:

• chr1-183023936-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_002293.4(LAMC1):​c.220G>C​(p.Glu74Gln) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,460,934 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: LAMC1 NM_002293.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.50

Genes affected

LAMC1 (HGNC:6492): (laminin subunit gamma 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, composed of 3 non identical chains: laminin alpha, beta and gamma (formerly A, B1, and B2, respectively), have 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 gamma chain isoform laminin, gamma 1. The gamma 1 chain, formerly thought to be a beta chain, contains structural domains similar to beta chains, however, lacks the short alpha region separating domains I and II. The structural organization of this gene also suggested that it had diverged considerably from the beta chain genes. Embryos of transgenic mice in which both alleles of the gamma 1 chain gene were inactivated by homologous recombination, lacked basement membranes, indicating that laminin, gamma 1 chain is necessary for laminin heterotrimer assembly. It has been inferred by analogy with the strikingly similar 3' UTR sequence in mouse laminin gamma 1 cDNA, that multiple polyadenylation sites are utilized in human to generate the 2 different sized mRNAs (5.5 and 7.5 kb) seen on Northern analysis. [provided by RefSeq, Aug 2011]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.833

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
LAMC1	NM_002293.4	c.220G>C	p.Glu74Gln	missense_variant	1/28	ENST00000258341.5	NP_002284.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
LAMC1	ENST00000258341.5	c.220G>C	p.Glu74Gln	missense_variant	1/28	1	NM_002293.4	ENSP00000258341	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1460934 Hom.: 0 Cov.: 34 AF XY: 0.00000138 AC XY: 1 AN XY: 726794

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: 0.0000166

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 17, 2024

The c.220G>C (p.E74Q) alteration is located in exon 1 (coding exon 1) of the LAMC1 gene. This alteration results from a G to C substitution at nucleotide position 220, causing the glutamic acid (E) at amino acid position 74 to be replaced by a glutamine (Q). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.32
BayesDel_addAF	Uncertain	0.096	D
BayesDel_noAF	Benign	-0.10
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Benign	0.23	T
Eigen	Pathogenic	0.72
Eigen_PC	Pathogenic	0.71
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Uncertain	0.86	D
M_CAP	Benign	0.057	D
MetaRNN	Pathogenic	0.83	D
MetaSVM	Uncertain	0.22	D
MutationAssessor	Uncertain	2.2	M
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.74	T
PROVEAN	Benign	-1.2	N
REVEL	Uncertain	0.56
Sift	Benign	0.26	T
Sift4G	Benign	0.18	T
Polyphen		0.99	D
Vest4		0.64
MutPred		0.78		Loss of glycosylation at P73 (P = 0.069);
MVP		0.77
MPC		1.1
ClinPred		0.98	D
GERP RS		4.8
Varity_R		0.33
gMVP		0.47

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs140378959; hg19: chr1-182993071;