rs72558486

Variant names:

• chrX-38421023-G-T
• rs72558486
• NM_000531.6:c.1006G>T

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1 PM2 PP2 PP3_Moderate PP5

The NM_000531.6(OTC):​c.1006G>T​(p.Ala336Ser) variant causes a missense, splice region 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. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (no stars). Synonymous variant affecting the same amino acid position (i.e. A336A) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 22)
• Consequence: OTC NM_000531.6 missense, splice_region
• Scores: Splicing: ADA: 0.9998
• Clinical Significance: Pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: 8.28
• Publications: 5 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.

• PM1: In a hotspot region, there are 10 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 9 uncertain in NM_000531.6
• PM2: Very rare variant in population databases, with high coverage
• 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. Scorers claiming Uncertain: max_spliceai. No scorers claiming Benign.
• PP5: Variant X-38421023-G-T is Pathogenic according to our data. Variant chrX-38421023-G-T is described in ClinVar as Pathogenic. ClinVar VariationId is 97094.Status of the report is no_assertion_criteria_provided, 0 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
OTC	NM_000531.6	c.1006G>T	p.Ala336Ser	missense_variant, splice_region_variant	Exon 10 of 10	ENST00000039007.5	NP_000522.3
OTC	NM_001407092.1	c.1006G>T	p.Ala336Ser	missense_variant, splice_region_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.1006G>T	p.Ala336Ser	missense_variant, splice_region_variant	Exon 10 of 10	1	NM_000531.6	ENSP00000039007.4
ENSG00000250349	ENST00000465127.1	c.172-245098G>T		intron_variant	Intron 3 of 8	5		ENSP00000417050.1

Frequencies

GnomAD3 genomes Cov.: 22

GnomAD4 exome Cov.: 26

GnomAD4 genome Cov.: 22

Alfa AF: 0.0000873 Hom.: 0

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: no assertion criteria provided

Submissions by phenotype

not provided Pathogenic:1

-

GenMed Metabolism Lab

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.21
BayesDel_addAF	Pathogenic	0.65	D
BayesDel_noAF	Pathogenic	0.69
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.89	D
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.93	D
M_CAP	Pathogenic	0.70	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	2.9	M
PhyloP100		8.3
PrimateAI	Uncertain	0.73	T
PROVEAN	Benign	-1.7	N
REVEL	Pathogenic	0.87
Sift	Benign	0.38	T
Sift4G	Benign	0.21	T
Polyphen		0.79	P
Vest4		0.60
MutPred		0.95		Gain of ubiquitination at K331 (P = 0.1117);
MVP		0.99
MPC		0.44
ClinPred		0.96	D
GERP RS		5.3
Varity_R		0.72
gMVP		0.93
Mutation Taster		=22/78	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.97
SpliceAI score (max)		0.48		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.48		Position offset: 0

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs72558486; hg19: chrX-38280276;