X-53236386-G-T

Variant names:

• chrX-53236386-G-T
• rs374220843
• NM_001111125.3:c.3387C>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_001111125.3(IQSEC2):​c.3387C>A​(p.Tyr1129*) variant causes a stop gained change involving the alteration of a non-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 Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. Y1129Y) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 24)
• Consequence: IQSEC2 NM_001111125.3 stop_gained
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: -0.331
• Publications: 2 publications found

Genes affected

IQSEC2 (HGNC:29059): (IQ motif and Sec7 domain ArfGEF 2) This gene encodes a guanine nucleotide exchange factor for the ARF family of small GTP-binding proteins. The encoded protein is a component of the postsynaptic density at excitatory synapses, and may play a critical role in cytoskeletal and synaptic organization through the activation of selected ARF substrates including ARF1 and ARF6. Mutations in this gene have been implicated in nonsyndromic X-linked cognitive disability. Alternatively spliced transcript variants encoding multiple isoforms have been observed for this gene. [provided by RefSeq, Aug 2011]

IQSEC2 Gene-Disease associations (from GenCC):

• complex neurodevelopmental disorder

  Inheritance: XL Classification: DEFINITIVE Submitted by: Ambry Genetics
• intellectual disability, X-linked 1

  Inheritance: XL Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• X-linked complex neurodevelopmental disorder

  Inheritance: XL Classification: DEFINITIVE Submitted by: ClinGen
• non-syndromic X-linked intellectual disability

  Inheritance: XL Classification: SUPPORTIVE Submitted by: Orphanet
• severe intellectual disability-progressive postnatal microcephaly- midline stereotypic hand movements syndrome

  Inheritance: XL Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 12 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 X-53236386-G-T is Pathogenic according to our data. Variant chrX-53236386-G-T is described in ClinVar as Pathogenic. ClinVar VariationId is 566884.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
IQSEC2	NM_001111125.3	c.3387C>A	p.Tyr1129*	stop_gained	Exon 13 of 15	ENST00000642864.1	NP_001104595.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
IQSEC2	ENST00000642864.1	c.3387C>A	p.Tyr1129*	stop_gained	Exon 13 of 15		NM_001111125.3	ENSP00000495726.1

Frequencies

GnomAD3 genomes Cov.: 24

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 24

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability, X-linked 1 Pathogenic:1

Apr 06, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. Loss-of-function variants in IQSEC2 are known to be pathogenic (PMID: 21686261, 26793055, 27665735). This variant has been observed in individual(s) with seizures and intellectual disability (PMID: 27652284, 30206421). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 566884). This variant is not present in population databases (ExAC no frequency). This sequence change creates a premature translational stop signal (p.Tyr1129*) in the IQSEC2 gene. It is expected to result in an absent or disrupted protein product. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.65	D
BayesDel_noAF	Pathogenic	0.55
CADD	Pathogenic	28
DANN	Uncertain	1.0
FATHMM_MKL	Benign	0.45	N
PhyloP100		-0.33
Vest4		0.41, 0.26
GERP RS		-0.073
Mutation Taster		=2/198	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: rs374220843; hg19: chrX-53265568;