Genetic Variant OTC:p.Ala217Gly (chrX-38403727-C-G) – ACMG Classification: Uncertain_significance (4 pts)

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2PP3_Moderate

The NM_000531.6(OTC):c.650C>G(p.Ala217Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000911 in 1,097,184 control chromosomes in the GnomAD database, with no homozygous occurrence. There are no hemizygote samples in GnomAD. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: not found (cov: 23)

Exomes 𝑓: 9.1e-7 ( 0 hom. 0 hem. )

Consequence

OTC
NM_000531.6 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 2.56

Variant links:

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 links:

ENSG00000250349 (HGNC:):

ENSG00000250349 links:

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ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 4 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.854

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
OTC	NM_000531.6 link	c.650C>G	p.Ala217Gly	missense_variant	Exon 6 of 10	ENST00000039007.5	NP_000522.3	P00480
OTC	NM_001407092.1 link	c.650C>G	p.Ala217Gly	missense_variant	Exon 8 of 12		NP_001394021.1
OTC	XM_017029556.2 link	c.650C>G	p.Ala217Gly	missense_variant	Exon 6 of 9		XP_016885045.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
OTC	ENST00000039007.5 link	c.650C>G	p.Ala217Gly	missense_variant	Exon 6 of 10	1	NM_000531.6	ENSP00000039007.4		P00480
ENSG00000250349	ENST00000465127.1 link	c.172-262394C>G		intron_variant	Intron 3 of 8	5		ENSP00000417050.1		B4E171

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

9.11e-7

AC:

AN:

1097184

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

362574

show subpopulations

Gnomad4 AFR exome

AF:

0.0000379

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.:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Ornithine carbamoyltransferase deficiency

Uncertain:1

Apr 03, 2023

All of Us Research Program, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces alanine with glycine at codon 217 of the OTC protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with OTC-related disorders 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. -

not provided

Uncertain:1

Aug 28, 2019

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed in large population cohorts (Lek et al., 2016); The majority of missense variants in this gene are considered pathogenic (Stenson et al., 2014); In silico analysis, which includes protein predictors and evolutionary conservation, supports a deleterious effect; Has not been previously published as pathogenic or benign to our knowledge -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.35

BayesDel_addAF

Pathogenic

0.32

BayesDel_noAF

Pathogenic

0.22

CADD

Benign

DANN

Uncertain

0.99

DEOGEN2

Pathogenic

0.93

FATHMM_MKL

Uncertain

0.86

LIST_S2

Uncertain

0.95

M_CAP

Pathogenic

0.80

MetaRNN

Pathogenic

0.85

MetaSVM

Uncertain

0.70

MutationAssessor

Benign

1.8

PrimateAI

Benign

0.29

PROVEAN

Uncertain

-3.1

REVEL

Uncertain

0.62

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0010

Polyphen

0.28

Vest4

0.59

MutPred

0.68

Gain of disorder (P = 0.0769);

MVP

0.99

MPC

0.56

ClinPred

0.97

GERP RS

1.6

Varity_R

0.85

gMVP

0.91

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.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over