rs1555381108

Variant names:

• chr13-101100882-T-C
• rs1555381108
• NM_052867.4:c.3064A>G

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1 PM2 PP2 PP5

The NM_052867.4(NALCN):​c.3064A>G​(p.Ile1022Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 33)
• Consequence: NALCN NM_052867.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 7.57
• Publications: 0 publications found

Genes affected

NALCN (HGNC:19082): (sodium leak channel, non-selective) This gene encodes a voltage-independent, nonselective cation channel which belongs to a family of voltage-gated sodium and calcium channels that regulates the resting membrane potential and excitability of neurons. This family is expressed throughout the nervous system and conducts a persistent sodium leak current that contributes to tonic neuronal excitability. The encoded protein forms a channelosome complex that includes G-protein-coupled receptors, UNC-79, UNC-80, NCA localization factor-1, and src family tyrosine kinases. Naturally occurring mutations in this gene are associated with infantile neuroaxonal dystrophy, infantile hypotonia with psychomotor retardation and characteristic facies (IHPRF) syndrome, and congenital contractures of the limbs and face with hypotonia and developmental delay (CLIFAHDD) syndrome. A knockout of the orthologous gene in mice results in paralysis with a severely disrupted respiratory rhythm, and lethality within 24 hours after birth. [provided by RefSeq, Apr 2017]

NALCN Gene-Disease associations (from GenCC):

• congenital contractures of the limbs and face, hypotonia, and developmental delay

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
• hypotonia, infantile, with psychomotor retardation and characteristic facies 1

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• digitotalar dysmorphism

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Freeman-Sheldon syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Sheldon-hall syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• hypotonia, infantile, with psychomotor retardation and characteristic facies

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• temporal lobe epilepsy

  Inheritance: AD Classification: LIMITED Submitted by: G2P

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 0 uncertain in NM_052867.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the NALCN gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 63 curated pathogenic missense variants (we use a threshold of 10). The gene has 9 curated benign missense variants. Gene score misZ: 4.9555 (above the threshold of 3.09). Trascript score misZ: 6.7536 (above the threshold of 3.09). GenCC associations: The gene is linked to congenital contractures of the limbs and face, hypotonia, and developmental delay, temporal lobe epilepsy, hypotonia, infantile, with psychomotor retardation and characteristic facies 1, Sheldon-hall syndrome, digitotalar dysmorphism, hypotonia, infantile, with psychomotor retardation and characteristic facies, Freeman-Sheldon syndrome.
• PP5: Variant 13-101100882-T-C is Pathogenic according to our data. Variant chr13-101100882-T-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 520429.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NALCN	NM_052867.4	c.3064A>G	p.Ile1022Val	missense_variant	Exon 27 of 44	ENST00000251127.11	NP_443099.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NALCN	ENST00000251127.11	c.3064A>G	p.Ile1022Val	missense_variant	Exon 27 of 44	1	NM_052867.4	ENSP00000251127.6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Congenital contractures of the limbs and face, hypotonia, and developmental delay Pathogenic:1 Uncertain:1

Feb 23, 2023

3billion

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The variant is not observed in the gnomAD v2.1.1 dataset. Missense changes are a common disease-causing mechanism. In silico tool predictions suggest damaging effect of the variant on gene or gene product (REVEL: 0.61; 3Cnet: 0.37). Same nucleotide change resulting in same amino acid change has been previously reported to be associated with autosomal dominant congenital contractures of the limbs and face, hypotonia, and developmental delay (ClinVar ID: VCV000520429). However, the evidence of pathogenicity is insufficient at this time. Therefore, this variant is classified as VUS according to the recommendation of ACMG/AMP guideline. -

Mar 22, 2018

Center For Human Genetics And Laboratory Diagnostics, Dr. Klein, Dr. Rost And Colleagues

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.069
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Uncertain	0.11
CADD	Benign	21
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.49	T
Eigen	Uncertain	0.26
Eigen_PC	Uncertain	0.41
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.91	D
M_CAP	Uncertain	0.10	D
MetaRNN	Uncertain	0.47	T
MetaSVM	Pathogenic	0.87	D
MutationAssessor	Benign	0.70	N
PhyloP100		7.6
PrimateAI	Pathogenic	0.85	D
PROVEAN	Benign	-0.11	N
REVEL	Uncertain	0.61
Sift	Benign	0.27	T
Sift4G	Benign	0.42	T
Polyphen		0.51	P
Vest4		0.57
MutPred		0.68		Gain of catalytic residue at S1021 (P = 0);
MVP		0.57
MPC		0.47
ClinPred		0.88	D
GERP RS		5.7
Varity_R		0.35
gMVP		0.49
Mutation Taster		=68/32	disease causing (ClinVar)

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

dbSNP: rs1555381108; hg19: chr13-101753233;