13-101229529-TA-T

Variant names:

• chr13-101229529-TA-T
• rs869025188
• NM_052867.4:c.1489delT

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_052867.4(NALCN):​c.1489delT​(p.Tyr497ThrfsTer21) variant causes a frameshift 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 Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 33)
• Consequence: NALCN NM_052867.4 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 8.80
• Publications: 1 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: Pathogenic. The variant received 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-101229529-TA-T is Pathogenic according to our data. Variant chr13-101229529-TA-T is described in ClinVar as [Pathogenic]. Clinvar id is 88686.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NALCN	NM_052867.4	c.1489delT	p.Tyr497ThrfsTer21	frameshift_variant	Exon 13 of 44	ENST00000251127.11	NP_443099.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NALCN	ENST00000251127.11	c.1489delT	p.Tyr497ThrfsTer21	frameshift_variant	Exon 13 of 44	1	NM_052867.4	ENSP00000251127.6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Apr 01, 2021

Revvity Omics, Revvity

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 26, 2016

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1489delT variant in the NALCN gene has been reported previously in the homozygous state in three Saudi Arabian siblings with delayed speech development, infantile hypotonia, easily controlled seizure disorder, hyperactivity, chronic constipation, and cognitive delay (Al-Sayed et al., 2013). The c.1489delT variant causes a frameshift starting with codon Tyrosine 497, changes this amino acid to a Threonine residue, and creates a premature Stop codon at position 21 of the new reading frame, denoted p.Tyr497ThrfsX21. This variant is predicted to cause loss of normal protein function either through protein truncation or nonsense-mediated mRNA decay. The c.1489delT variant was not observed in approximately 6500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. We interpret c.1489delT as a pathogenic variant. -

Hypotonia, infantile, with psychomotor retardation and characteristic facies 1 Pathogenic:1

Oct 03, 2013

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		8.8
Mutation Taster		=0/200	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: rs869025188; hg19: chr13-101881880;