chr1-183252731-C-G

Variant names:

• chr1-183252731-C-G
• NM_015039.4:c.834G>C

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PP2

The NM_015039.4(NMNAT2):​c.834G>C​(p.Gln278His) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: NMNAT2 NM_015039.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.85
• Publications: 0 publications found

Genes affected

NMNAT2 (HGNC:16789): (nicotinamide nucleotide adenylyltransferase 2) This gene product belongs to the nicotinamide mononucleotide adenylyltransferase (NMNAT) enzyme family, members of which catalyze an essential step in NAD (NADP) biosynthetic pathway. Unlike the other human family member, which is localized to the nucleus, and is ubiquitously expressed; this enzyme is cytoplasmic, and is predominantly expressed in the brain. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]

ENSG00000287929 (HGNC:):

LAMC2 (HGNC:6493): (laminin subunit gamma 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), 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 2. The gamma 2 chain, formerly thought to be a truncated version of beta chain (B2t), is highly homologous to the gamma 1 chain; however, it lacks domain VI, and domains V, IV and III are shorter. It is expressed in several fetal tissues but differently from gamma 1, and is specifically localized to epithelial cells in skin, lung and kidney. The gamma 2 chain together with alpha 3 and beta 3 chains constitute laminin 5 (earlier known as kalinin), which is an integral part of the anchoring filaments that connect epithelial cells to the underlying basement membrane. The epithelium-specific expression of the gamma 2 chain implied its role as an epithelium attachment molecule, and mutations in this gene have been associated with junctional epidermolysis bullosa, a skin disease characterized by blisters due to disruption of the epidermal-dermal junction. Two transcript variants resulting from alternative splicing of the 3' terminal exon, and encoding different isoforms of gamma 2 chain, have been described. The two variants are differentially expressed in embryonic tissues, however, the biological significance of the two forms is not known. Transcript variants utilizing alternative polyA_signal have also been noted in literature. [provided by RefSeq, Aug 2011]

LAMC2 Gene-Disease associations (from GenCC):

• junctional epidermolysis bullosa

  Inheritance: AR Classification: DEFINITIVE Submitted by: Myriad Women’s Health
• junctional epidermolysis bullosa Herlitz type

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, Genomics England PanelApp, PanelApp Australia
• junctional epidermolysis bullosa, non-Herlitz type

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp, PanelApp Australia
• generalized junctional epidermolysis bullosa non-Herlitz type

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 1 curated pathogenic missense variants (we use a threshold of 10). The gene has 0 curated benign missense variants. Gene score misZ: 2.1005 (below the threshold of 3.09). Trascript score misZ: 2.0325 (below the threshold of 3.09).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NMNAT2	NM_015039.4	c.834G>C	p.Gln278His	missense_variant	Exon 11 of 11	ENST00000287713.7	NP_055854.1
NMNAT2	NM_170706.4	c.819G>C	p.Gln273His	missense_variant	Exon 11 of 11		NP_733820.1
LAMC2	XM_047420358.1	c.3329-5378C>G		intron_variant	Intron 22 of 23		XP_047276314.1
LAMC2	XM_047420361.1	c.3329-5991C>G		intron_variant	Intron 22 of 22		XP_047276317.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NMNAT2	ENST00000287713.7	c.834G>C	p.Gln278His	missense_variant	Exon 11 of 11	1	NM_015039.4	ENSP00000287713.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Dec 12, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.834G>C (p.Q278H) alteration is located in exon 11 (coding exon 11) of the NMNAT2 gene. This alteration results from a G to C substitution at nucleotide position 834, causing the glutamine (Q) at amino acid position 278 to be replaced by a histidine (H). 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	Pathogenic	0.89
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.26
CADD	Benign	22
DANN	Uncertain	0.98
DEOGEN2	Benign	0.032	.;T
Eigen	Uncertain	0.56
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.92	D;D
M_CAP	Pathogenic	0.30	D
MetaRNN	Uncertain	0.53	D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Benign	0.0	.;N
PhyloP100		5.8
PrimateAI	Uncertain	0.78	T
PROVEAN	Benign	-0.92	N;N
REVEL	Uncertain	0.62
Sift	Benign	0.043	D;D
Sift4G	Uncertain	0.049	D;D
Polyphen		0.99	D;D
Vest4		0.34
MutPred		0.32		.;Loss of stability (P = 0.0465);
MVP		0.93
MPC		1.8
ClinPred		0.81	D
GERP RS		5.6
Varity_R		0.22
gMVP		0.82
Mutation Taster		=57/43	polymorphism

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

Other links and lift over

hg19: chr1-183221866;