X-38352773-G-T

Variant names:

• chrX-38352773-G-T
• rs68031618
• NM_000531.6:c.77G>T

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM2 PM5 PP2 PP3 PP5_Moderate

The NM_000531.6(OTC):​c.77G>T​(p.Arg26Leu) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R26P) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 23)
• Consequence: OTC NM_000531.6 missense, splice_region
• Scores: Splicing: ADA: 0.9651
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 1.65
• 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: Likely_pathogenic. The variant received 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrX-38352773-G-C is described in ClinVar as Pathogenic. ClinVar VariationId is 97319.Status of the report is no_assertion_criteria_provided, 0 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: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.
• PP5: Variant X-38352773-G-T is Pathogenic according to our data. Variant chrX-38352773-G-T is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 1685390.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000531.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	OTC	NM_000531.6	MANE Select	c.77G>T	p.Arg26Leu	missense splice_region	Exon 1 of 10	NP_000522.3
	OTC	NM_001407092.1		c.77G>T	p.Arg26Leu	missense splice_region	Exon 3 of 12	NP_001394021.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	OTC	ENST00000039007.5	TSL:1 MANE Select	c.77G>T	p.Arg26Leu	missense splice_region	Exon 1 of 10	ENSP00000039007.4
	ENSG00000250349	ENST00000465127.1	TSL:5	c.172-313348G>T		intron	N/A	ENSP00000417050.1
	OTC	ENST00000713758.1		c.77G>T	p.Arg26Leu	missense splice_region	Exon 3 of 12	ENSP00000519059.1

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 26

GnomAD4 genome Cov.: 23

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Ornithine carbamoyltransferase deficiency Pathogenic:1

May 04, 2022

Mendelics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.12
BayesDel_addAF	Uncertain	0.088	D
BayesDel_noAF	Benign	-0.11
CADD	Benign	23
DANN	Uncertain	0.99
DEOGEN2	Benign	0.37	T
FATHMM_MKL	Uncertain	0.81	D
LIST_S2	Benign	0.66	T
M_CAP	Pathogenic	0.79	D
MetaRNN	Uncertain	0.47	T
MetaSVM	Uncertain	0.57	D
MutationAssessor	Benign	1.8	L
PhyloP100		1.6
PrimateAI	Benign	0.22	T
PROVEAN	Benign	-0.32	N
REVEL	Uncertain	0.39
Sift	Benign	0.15	T
Sift4G	Benign	0.69	T
Polyphen		0.014	B
Vest4		0.40
MutPred		0.57		Loss of solvent accessibility (P = 0.0079)
MVP		0.70
MPC		0.49
ClinPred		0.24	T
GERP RS		3.8
PromoterAI		-0.17	Neutral
Varity_R		0.12
gMVP		0.80
Mutation Taster		=71/29	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.97
dbscSNV1_RF	Pathogenic	0.83
SpliceAI score (max)		0.030		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: rs68031618; hg19: chrX-38212026;