X-38401292-C-T

Position:

• chrX-38401292-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_000531.6(OTC):​c.404C>T​(p.Ala135Val) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 23)
  • Exomes 𝑓: 0.0 (0 hom. 0 hem.)
  • Failed GnomAD Quality Control
• Consequence: OTC NM_000531.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.96

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 Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
OTC	NM_000531.6	c.404C>T	p.Ala135Val	missense_variant	5/10	ENST00000039007.5	NP_000522.3
OTC	NM_001407092.1	c.404C>T	p.Ala135Val	missense_variant	7/12		NP_001394021.1
OTC	XM_017029556.2	c.404C>T	p.Ala135Val	missense_variant	5/9		XP_016885045.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
OTC	ENST00000039007.5	c.404C>T	p.Ala135Val	missense_variant	5/10	1	NM_000531.6	ENSP00000039007.4
ENSG00000250349	ENST00000465127.1	c.172-264829C>T		intron_variant		5		ENSP00000417050.1

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1090191 Hom.: 0 Cov.: 28 AF XY: 0.00 AC XY: 0 AN XY: 356059

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 23

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Ornithine carbamoyltransferase deficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

All of Us Research Program, National Institutes of Health

Apr 10, 2023

This missense variant replaces alanine with valine at codon 135 of the OTC protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with ornithine carbamoyltransferase deficiency in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.16
BayesDel_addAF	Pathogenic	0.19	D
BayesDel_noAF	Uncertain	0.030
CADD	Benign	20
DANN	Benign	0.93
DEOGEN2	Uncertain	0.62	D
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	D
M_CAP	Pathogenic	0.41	D
MetaRNN	Uncertain	0.56	D
MetaSVM	Benign	-0.41	T
MutationAssessor	Benign	-0.69	N
PrimateAI	Uncertain	0.66	T
PROVEAN	Benign	1.0	N
REVEL	Uncertain	0.46
Sift	Benign	0.54	T
Sift4G	Benign	1.0	T
Polyphen		0.0010	B
Vest4		0.46
MutPred		0.64		Gain of helix (P = 0.132);
MVP		0.79
MPC		0.37
ClinPred		0.88	D
GERP RS		6.0
Varity_R		0.48
gMVP		0.75

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

LitVar

Other links and lift over

dbSNP: rs72556256; hg19: chrX-38260545;