X-25004744-C-T

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PP3_Strong PP5_Moderate

The NM_139058.3(ARX):c.1615G>A(p.Ala539Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A539V) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 25)
• Consequence: ARX NM_139058.3 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.32

Genes affected

ARX (HGNC:18060): (aristaless related homeobox) This gene is a homeobox-containing gene expressed during development. The expressed protein contains two conserved domains, a C-peptide (or aristaless domain) and the prd-like class homeobox domain. It is a member of the group-II aristaless-related protein family whose members are expressed primarily in the central and/or peripheral nervous system. This gene is thought to be involved in CNS development. Expansion of a polyalanine tract and other mutations in this gene cause X-linked cognitive disability and epilepsy. [provided by RefSeq, Jul 2016]

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_139058.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.987
• PP5: Variant X-25004744-C-T is Pathogenic according to our data. Variant chrX-25004744-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1516361.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ARX	NM_139058.3	c.1615G>A	p.Ala539Thr	missense_variant	5/5	ENST00000379044.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ARX	ENST00000379044.5	c.1615G>A	p.Ala539Thr	missense_variant	5/5	1	NM_139058.3	P1

Frequencies

GnomAD3 genomes Cov.: 25

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 25

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability, X-linked, with or without seizures, arx-related;C3463992:Developmental and epileptic encephalopathy, 1 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Invitae

Aug 09, 2021

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Ala539 amino acid residue in ARX. Other variant(s) that disrupt this residue have been observed in individuals with ARX-related conditions (PMID: 28174645, Invitae), which suggests that this may be a clinically significant amino acid residue. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt ARX protein function. This variant has been observed in individual(s) with clinical features of developmental and epileptic encephalopathy (Invitae). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate insufficient coverage at this position in the ExAC database. This sequence change replaces alanine with threonine at codon 539 of the ARX protein (p.Ala539Thr). The alanine residue is highly conserved and there is a small physicochemical difference between alanine and threonine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.56
Cadd	Pathogenic	32
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.73	D
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.91	D
M_CAP	Pathogenic	0.99	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.4	M
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.91	D
PROVEAN	Uncertain	-3.4	D
REVEL	Pathogenic	0.88
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.0040	D
Polyphen		0.59	P
Vest4		0.95
MutPred		0.91		Gain of phosphorylation at A539 (P = 0.0306);
MVP		1.0
MPC		2.3
ClinPred		0.99	D
GERP RS		3.3
Varity_R		0.98
gMVP		0.90

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: chrX-25022861;