X-38411923-A-T

Variant names:

• chrX-38411923-A-T
• NM_000531.6:c.929A>T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PP3_Strong PP5_Moderate

The NM_000531.6(OTC):​c.929A>T​(p.Glu310Val) 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 Pathogenic (★).

• Frequency: Genomes: not found (cov: 23)
• Consequence: OTC NM_000531.6 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 8.79

Genes affected

OTC (HGNC:8512): (ornithine transcarbamylase) This nuclear gene encodes a mitochondrial matrix enzyme. The encoded protein is involved in the urea cycle which functions to detoxify ammonia into urea for excretion. Mutations in this enzyme lead to ornithine transcarbamylase deficiency, which causes hyperammonemia. [provided by RefSeq, May 2022]

ENSG00000250349 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.981
• PP5: Variant X-38411923-A-T is Pathogenic according to our data. Variant chrX-38411923-A-T is described in ClinVar as [Pathogenic]. Clinvar id is 2036350.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
OTC	NM_000531.6	c.929A>T	p.Glu310Val	missense_variant	Exon 9 of 10	ENST00000039007.5	NP_000522.3
OTC	NM_001407092.1	c.929A>T	p.Glu310Val	missense_variant	Exon 11 of 12		NP_001394021.1
OTC	XM_017029556.2	c.*62A>T		downstream_gene_variant			XP_016885045.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
OTC	ENST00000039007.5	c.929A>T	p.Glu310Val	missense_variant	Exon 9 of 10	1	NM_000531.6	ENSP00000039007.4
ENSG00000250349	ENST00000465127.1	c.172-254198A>T		intron_variant	Intron 3 of 8	5		ENSP00000417050.1
OTC	ENST00000643344.1	n.*679A>T		non_coding_transcript_exon_variant	Exon 10 of 11			ENSP00000496606.1
OTC	ENST00000643344.1	n.*679A>T		3_prime_UTR_variant	Exon 10 of 11			ENSP00000496606.1

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 23

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Ornithine carbamoyltransferase deficiency Pathogenic:1

Apr 24, 2023

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. This variant disrupts the p.Glu310 amino acid residue in OTC. Other variant(s) that disrupt this residue have been observed in individuals with OTC-related conditions (PMID: 16786505, 28266016, 30626930; Invitae), which suggests that this may be a clinically significant amino acid residue. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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 OTC protein function. ClinVar contains an entry for this variant (Variation ID: 2036350). This missense change has been observed in individual(s) with clinical features of ornithine transcarbamylase deficiency (Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glutamic acid, which is acidic and polar, with valine, which is neutral and non-polar, at codon 310 of the OTC protein (p.Glu310Val). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.74	D
BayesDel_noAF	Pathogenic	0.82
CADD	Pathogenic	28
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.99	D
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.90	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	0.93	D
MutationAssessor	Pathogenic	4.6	H
PrimateAI	Uncertain	0.63	T
PROVEAN	Pathogenic	-6.7	D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.94
MutPred		0.80		Gain of catalytic residue at E310 (P = 0.0055);
MVP		1.0
MPC		1.3
ClinPred		1.0	D
GERP RS		5.2
Varity_R		0.98
gMVP		1.0

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-38271176;