X-38421056-C-T

Variant names:

• chrX-38421056-C-T
• rs72558493
• NM_000531.6:c.1039C>T

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate PP5_Moderate

The NM_000531.6(OTC):​c.1039C>T​(p.Pro347Ser) variant causes a missense change. 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P347R) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 23)
• Consequence: OTC NM_000531.6 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 6.56
• Publications: 0 publications found

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]

OTC Gene-Disease associations (from GenCC):

• ornithine carbamoyltransferase deficiency

  Inheritance: XL Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, G2P, Laboratory for Molecular Medicine, Orphanet

ENSG00000250349 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 11 ACMG points.

• PM1: In a hotspot region, there are 12 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_000531.6
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrX-38421056-C-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 97102.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 266 curated pathogenic missense variants (we use a threshold of 10). The gene has 15 curated benign missense variants. Gene score misZ: 1.3274 (below the threshold of 3.09). Trascript score misZ: NaN (below the threshold of 3.09). GenCC associations: The gene is linked to ornithine carbamoyltransferase deficiency.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.884
• PP5: Variant X-38421056-C-T is Pathogenic according to our data. Variant chrX-38421056-C-T is described in ClinVar as Pathogenic. ClinVar VariationId is 2138547.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.1039C>T	p.Pro347Ser	missense_variant	Exon 10 of 10	ENST00000039007.5	NP_000522.3
OTC	NM_001407092.1	c.1039C>T	p.Pro347Ser	missense_variant	Exon 12 of 12		NP_001394021.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
OTC	ENST00000039007.5	c.1039C>T	p.Pro347Ser	missense_variant	Exon 10 of 10	1	NM_000531.6	ENSP00000039007.4
ENSG00000250349	ENST00000465127.1	c.172-245065C>T		intron_variant	Intron 3 of 8	5		ENSP00000417050.1

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 27

GnomAD4 genome Cov.: 23

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Ornithine carbamoyltransferase deficiency Pathogenic:1

Jul 17, 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.Pro347 amino acid residue in OTC. Other variant(s) that disrupt this residue have been observed in individuals with OTC-related conditions (PMID: 16786505, 26059767), 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 OTC protein function. ClinVar contains an entry for this variant (Variation ID: 2138547). This missense change has been observed in individuals with OTC deficiency (PMID: 26059767; Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces proline, which is neutral and non-polar, with serine, which is neutral and polar, at codon 347 of the OTC protein (p.Pro347Ser). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.64
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.34
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.47	T
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.91	D
M_CAP	Pathogenic	0.77	D
MetaRNN	Pathogenic	0.88	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	2.9	M
PhyloP100		6.6
PrimateAI	Uncertain	0.57	T
PROVEAN	Benign	-2.1	N
REVEL	Pathogenic	0.80
Sift	Benign	0.048	D
Sift4G	Benign	0.10	T
Polyphen		1.0	D
Vest4		0.85
MutPred		0.53		Gain of helix (P = 0.062);
MVP		0.95
MPC		1.1
ClinPred		0.98	D
GERP RS		5.3
Varity_R		0.68
gMVP		0.95
Mutation Taster		=19/81	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs72558493; hg19: chrX-38280309;