OTC

Chr XX-linked

ornithine transcarbamylase

Also known as: OCTD, OTC1, OTCD, OTCase

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]

OMIMResearchGenerating clinical summary…

Primary Disease Associations & Inheritance

Ornithine transcarbamylase deficiencyMIM #311250
X-linked
UniProtOrnithine carbamoyltransferase deficiency

Clinical highlights

Gene-disease validity (ClinGen)
ornithine carbamoyltransferase deficiency · XLDefinitivesufficient evidence for diagnostic panels
Interpreting a novel variant
Loss of function is the curated mechanism (Gene2Phenotype) and the gene is intolerant of it in the population — truncating, frameshift and canonical splice variants carry more prior weight here than missense.Curated gene-level mechanism — a prior for triage, not a per-variant call.
12
Active trials
937
Pubs (1 yr)
P/LP submissions
P/LP missense
0.41
LOEUF
LOF
Mechanism· G2P

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Moderate LoF intolerance
LoF Constraint?
0.41LOEUF
pLI 0.873
Z-score 3.18
OE 0.13 (0.050.41)
Moderately constrained

More LoF-intolerant than ~75% of genes

Missense Constraint?
1.33Z-score
OE missense 0.67 (0.570.81)
89 obs / 131.9 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios?
LoF OE?0.13 (0.050.41)
00.351.4
Missense OE?0.67 (0.570.81)
00.61.4
Synonymous OE?0.97
01.21.6
LoF obs/exp: 2 / 15.5Missense obs/exp: 89 / 131.9Syn Z: 0.19

ClinVar Variant Classifications

0 submitted variants in ClinVar

Protein Context — Lollipop Plot

OTC · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

VCEP specificationsUrea Cycle DisordersReleased
Panel ↗

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

Intellectual Disability, MildIntellectual Disability, Mild to ModerateDevelopmental Disability

PGx Medication Safety Reviews of Persons With IDD

NOT YET RECRUITING
NCT07092852GalenusRx, Inc.Started 2025-08-01
Cheek swab for PGx testingMedication safety review
Schizophrenia and Related DisordersMitochondrial AlterationCognitive Impairment

MitoQ for Early-phase Schizophrenia-spectrum Disorder and Mitochondrial Dysfunction

RECRUITING
NCT06191965Phase PHASE2, PHASE3Mclean HospitalStarted 2024-06-01
MitoQPlacebo
Ornithine Transcarbamylase DeficiencyOrnithine Transcarbamylase Deficiency DiseaseOrnithine Carbamoyltransferase Deficiency (Disorder)

An Open-label Study to Investigate ECUR-506 in Male Babies Less Than 9 Months of Age With Neonatal Onset OTC Deficiency

RECRUITING
NCT06255782Phase PHASE3iECURE, Inc.Started 2024-04-08
ECUR-506
Lynch Syndrome I (Site-specific Colonic Cancer)

Finding the Best Dose of Aspirin to Prevent Lynch Syndrome Cancers

NOT YET RECRUITING
NCT02497820Phase PHASE3Tel-Aviv Sourasky Medical CenterStarted 2016-09
Aspirin
Microbial ColonizationEye DiseasesOphthalmopathy

Assessment of the Ocular Microbiome in Health and Disease

RECRUITING
NCT05414994Vanderbilt University Medical CenterStarted 2023-09-07
Eye swab
COVID -19Influenza AInfluenza B

Clinical Validation of the Aptitude Medical Systems Metrix Respiratory Panel Test in At-Home/Non-Laboratory Settings

NOT YET RECRUITING
NCT07217639Phase NAAptitude Medical SystemsStarted 2025-11-01
Aptitude Medical Systems Respiratory Panel Test
Alcohol Drinking

Nicotinic Receptor Genetic Variation and Alcohol Reward

RECRUITING
NCT03294460Phase PHASE1National Institute on Alcohol Abuse and Alcoholism (NIAAA)Started 2019-06-10
Alcohol (Oral)Alcohol (IV)Alcohol (Ethanol)
Oral Health

Administration of Oral Probiotic Streptococcus Salivarius K12

ACTIVE NOT RECRUITING
NCT07757360Phase NAUniversity of ZurichStarted 2026-05-06
Probiotic
OTC Deficiency

Clinical Study of DTX301 AAV-Mediated Gene Transfer for Ornithine Transcarbamylase (OTC) Deficiency

ACTIVE NOT RECRUITING
NCT05345171Phase PHASE3Ultragenyx Pharmaceutical IncStarted 2022-10-18
DTX301PlaceboOral Corticosteroids
Preterm Birth ComplicationPreterm BirthPreterm Birth Recurrence

Personalized Care for Prenatal Stress Reduction & Prevention of Preterm Birth (PTB) Disparities

NOT YET RECRUITING
NCT06915428Phase NAUniversity of North Carolina, Chapel HillStarted 2026-08-01
Care coordinationElectronic massagesupport gift #1
Optical Coherence Tomography (OCT) of the RetinaMutation

Looking for VUS to Confirm Dominant Wolfram-like Syndrome Instead of Recessive Wolfram Syndrome

ACTIVE NOT RECRUITING
NCT07485413Hôpital Necker-Enfants MaladesStarted 2026-03-08
Impaired Glucose RegulationImpaired Glucose Tolerance (Prediabetes)Prediabetes (Insulin Resistance, Impaired Glucose Tolerance)

Probiotic Impact on Cognitive Performance, and Metabolic Outcomes in Overweight Young Adults With Impaired Glucose Regulation

RECRUITING
NCT07073781Phase NALeeds Beckett UniversityStarted 2025-08-15
Lab4p Probiotic ConsortiumPlacebo