Hereditary orotic aciduria is an autosomal recessive inborn disorder of pyrimidine metabolism caused by biallelic loss-of-function variants in UMPS, encoding the bifunctional uridine monophosphate synthetase enzyme. Defective de novo UMP synthesis produces massive urinary orotic acid overexcretion, megaloblastic anemia, global developmental delay, and failure to thrive, with additional congenital and immune features in some patients.
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name: Hereditary Orotic Aciduria
creation_date: "2026-05-11T11:08:06Z"
updated_date: "2026-05-19T08:14:52Z"
category: Mendelian
synonyms:
- Orotidylic decarboxylase deficiency
- Uridine monophosphate synthetase deficiency
description: >-
Hereditary orotic aciduria is an autosomal recessive inborn disorder of
pyrimidine metabolism caused by biallelic loss-of-function variants in UMPS,
encoding the bifunctional uridine monophosphate synthetase enzyme. Defective
de novo UMP synthesis produces massive urinary orotic acid overexcretion,
megaloblastic anemia, global developmental delay, and failure to thrive, with
additional congenital and immune features in some patients.
disease_term:
preferred_term: hereditary orotic aciduria
term:
id: MONDO:0009797
label: orotic aciduria
parents:
- inborn disorder of pyrimidine metabolism
- vitamin B12- and folate-independent constitutional megaloblastic anemia
has_subtypes:
- name: Type I
display_name: Type I (OPRT and ODC deficiency)
description: >-
Biochemical subtype with loss of both orotate phosphoribosyltransferase and
orotidine-5'-monophosphate decarboxylase activities of UMPS.
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Type I is caused by loss of both enzyme activities of the UMP enzyme."
explanation: The case-report discussion summarizes the established biochemical subtype definition.
- name: Type II
display_name: Type II (ODC deficiency)
description: >-
Biochemical subtype attributed to selective inactivation of the
orotidine-5'-monophosphate decarboxylase activity of UMPS.
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Type II is thought to be due to specific inactivation of OMPdecase."
explanation: The case-report discussion summarizes the Type II enzymatic subtype.
- name: Type III
display_name: Type III / OAWA (without megaloblastic anemia)
description: >-
Historical subtype also called orotic aciduria without megaloblastic anemia;
the pre-molecular reports are uncertain because later discussion notes that
those individuals may have represented carriers.
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: "Type III, also called orotic aciduria without megaloblastic anemia (OAWA), is expected to be also secondary to the inactivation of OMPdecase [1]."
explanation: The literature recognizes Type III/OAWA, but its molecular status is less certain than Types I and II.
mappings:
mondo_mappings:
- term:
id: MONDO:0009797
label: orotic aciduria
mapping_predicate: skos:exactMatch
mapping_source: MONDO
mapping_justification: MONDO exact match for Orphanet ORPHA:30 and OMIM:258900.
prevalence:
- population: Worldwide
percentage: "<1 / 1 000 000"
notes: Orphanet reports worldwide point prevalence below 1 per 1,000,000.
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "<1 / 1 000 000 | Worldwide | Point prevalence | PMID:25757096"
explanation: Orphanet provides the worldwide point-prevalence estimate.
inheritance:
- name: Autosomal recessive
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "Autosomal recessive"
explanation: Orphanet records autosomal recessive inheritance.
progression:
- phase: Neonatal to infantile-onset pyrimidine synthesis disorder
age_range: Neonatal period through infancy
notes: >-
Orphanet records neonatal and infantile onset, with early megaloblastic
anemia, developmental delay, failure to thrive, and massive urinary orotic
acid excretion.
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "Age of onset: Neonatal"
explanation: Orphanet records neonatal onset.
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "Age of onset: Infancy"
explanation: Orphanet records infantile onset.
pathophysiology:
- name: UMPS Loss of Function
description: >-
Biallelic UMPS loss-of-function variants impair uridine monophosphate
synthetase, the initiating enzymatic defect in hereditary orotic aciduria.
genes:
- preferred_term: UMPS
term:
id: hgnc:12563
label: UMPS
molecular_functions:
- preferred_term: orotate phosphoribosyltransferase activity
term:
id: GO:0004588
label: orotate phosphoribosyltransferase activity
modifier: DECREASED
- preferred_term: orotidine-5'-phosphate decarboxylase activity
term:
id: GO:0004590
label: orotidine-5'-phosphate decarboxylase activity
modifier: DECREASED
biological_processes:
- preferred_term: "'de novo' UMP biosynthetic process"
term:
id: GO:0044205
label: "'de novo' UMP biosynthetic process"
modifier: DECREASED
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "UMPS | uridine monophosphate synthetase | hgnc:12563 | Disease-causing germline mutation(s) (loss of function) in"
explanation: Orphanet identifies UMPS loss-of-function germline variants as disease causing.
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The analysis demonstrated a previously unreported homozygous pathogenic variant in the UMPS gene (c.1010C > G; A337G) confirming a diagnosis of HOA."
explanation: Human trio exome sequencing confirmed biallelic UMPS disease in the reported patient.
downstream:
- target: UMP Synthetase Enzymatic Block
description: UMPS loss of function reduces the two-step conversion of orotate to UMP.
causal_link_type: DIRECT
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "It is the only known enzyme deficiency of the pyrimidine biosynthetic pathway, resulting from a deficiency in one or both of the activities of the bifunctional enzyme uridine-5-monophosphate synthase (UMPS) (EC 4.1.1.23) encoded by the UMPS gene."
explanation: The article directly links UMPS deficiency to the enzymatic block in the pyrimidine biosynthetic pathway.
- name: UMP Synthetase Enzymatic Block
description: >-
Deficient UMPS blocks de novo UMP synthesis through impaired orotate
phosphoribosyltransferase and/or OMP decarboxylase activity, causing orotate
accumulation and urinary excretion.
chemical_entities:
- preferred_term: orotic acid
term:
id: CHEBI:16742
label: orotic acid
modifier: INCREASED
- preferred_term: uridine 5'-monophosphate
term:
id: CHEBI:16695
label: uridine 5'-monophosphate
modifier: DECREASED
biological_processes:
- preferred_term: "'de novo' UMP biosynthetic process"
term:
id: GO:0044205
label: "'de novo' UMP biosynthetic process"
modifier: DECREASED
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "In the first reaction, orotate phosphoribosyltransferase (OPRTase) converts orotate to orotidine monophosphate via ribosylation. In the second step, orotidine decarboxylase (OMPdecase) decarboxylates orotidine monophosphate to uridine monophosphate [1]."
explanation: The review portion of the article defines the two enzymatic steps carried by UMPS.
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "UMPS defects lead to the accumulation of orotate (OA) and/or of orotidine monophosphate (OMP), which will eventually be excreted in the urine [8]."
explanation: The article links the enzymatic block to orotate/OMP accumulation and urinary excretion.
downstream:
- target: Oroticaciduria
description: Orotate accumulation produces urinary overexcretion of orotic acid.
causal_link_type: DIRECT
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "UMPS defects lead to the accumulation of orotate (OA) and/or of orotidine monophosphate (OMP), which will eventually be excreted in the urine [8]."
explanation: The article directly connects the UMPS block to urinary metabolite excretion.
- target: Megaloblastic anemia
description: Pyrimidine nucleotide deficiency affects rapidly dividing marrow precursors, producing megaloblastic anemia.
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- megaloblastic erythropoietic failure
evidence:
- reference: PMID:36999056
reference_title: "Hereditary orotic aciduria identified by newborn screening."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Untreated, affected individuals may develop refractory megaloblastic anemia, neurodevelopmental disabilities, and crystalluria."
explanation: Review background in the newborn-screening cohort supports megaloblastic anemia as an untreated disease consequence.
- target: Global developmental delay
description: The untreated UMPS block is associated with neurodevelopmental disability and developmental delay.
causal_link_type: UNKNOWN
evidence:
- reference: PMID:36999056
reference_title: "Hereditary orotic aciduria identified by newborn screening."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Untreated, affected individuals may develop refractory megaloblastic anemia, neurodevelopmental disabilities, and crystalluria."
explanation: The newborn-screening report links untreated hereditary orotic aciduria to neurodevelopmental disability.
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "A rare genetic disorder of pyrimidine metabolism characterized by early onset of megaloblastic anemia, global developmental delay, and failure to thrive"
explanation: Orphanet lists global developmental delay among core disease features.
- target: Failure to thrive
description: The UMPS block is associated with impaired growth and failure to thrive.
causal_link_type: UNKNOWN
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Immunodeficiency, developmental delay and failure to thrive have been observed [2,9]."
explanation: The case-report review links failure to thrive to hereditary orotic aciduria.
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "A rare genetic disorder of pyrimidine metabolism characterized by early onset of megaloblastic anemia, global developmental delay, and failure to thrive"
explanation: Orphanet lists failure to thrive among core disease features.
- target: Orotic acid crystalluria
description: Urinary orotic acid excess can produce orotic acid crystalluria.
causal_link_type: DIRECT
evidence:
- reference: PMID:36999056
reference_title: "Hereditary orotic aciduria identified by newborn screening."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Untreated, affected individuals may develop refractory megaloblastic anemia, neurodevelopmental disabilities, and crystalluria."
explanation: The newborn-screening report identifies crystalluria as an untreated disease manifestation.
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "associated with massive urinary overexcretion of orotic acid (sometimes with orotic acid crystalluria)"
explanation: Orphanet directly links urinary orotic acid overexcretion with orotic acid crystalluria.
- target: Seizure
description: UMPS deficiency can present with epilepsy or seizure phenotypes, although the precise mechanism is unresolved.
causal_link_type: UNKNOWN
evidence:
- reference: PMID:25757096
reference_title: "Hereditary orotic aciduria with epilepsy and without megaloblastic anemia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "This report describes a new case of UMPS deficiency without megaloblastic anemia but with epilepsy."
explanation: A human case report directly associates UMPS deficiency with epilepsy.
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "Patients without megaloblastic anemia, but with additional manifestations such as epilepsy, have also been reported."
explanation: Orphanet records epilepsy as an additional hereditary orotic aciduria manifestation.
- target: T Cell Immunodeficiency
description: The UMPS block is associated with selective T-cell functional impairment.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "It has been reported that the main immunodeficiency in patients with HOA is the selective impairment in T cell function with intact humoral immunity."
explanation: The case-report discussion links HOA to selective T-cell functional impairment.
- target: Anemia
description: Pyrimidine nucleotide deficiency causes megaloblastic marrow changes that manifest clinically as anemia.
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- megaloblastic erythropoietic failure
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0001903 | Anemia | Very frequent (99-80%)"
explanation: Orphanet lists anemia as a very frequent hereditary orotic aciduria phenotype.
- target: Aminoaciduria
description: Aminoaciduria is reported in hereditary orotic aciduria, but the cached evidence does not define the renal tubular intermediate.
causal_link_type: UNKNOWN
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0003355 | Aminoaciduria | Very frequent (99-80%)"
explanation: Orphanet lists aminoaciduria as a very frequent hereditary orotic aciduria phenotype.
- target: Abnormality of the ureter
description: Ureter abnormality is reported in hereditary orotic aciduria, but the causal developmental intermediate is not resolved in cached evidence.
causal_link_type: UNKNOWN
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0000069 | Abnormality of the ureter | Frequent (79-30%)"
explanation: Orphanet lists abnormality of the ureter as a frequent phenotype.
- target: Hypertelorism
description: Hypertelorism is part of the reported congenital phenotype spectrum; the cached evidence does not specify a causal morphogenetic intermediate.
causal_link_type: UNKNOWN
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0000316 | Hypertelorism | Frequent (79-30%)"
explanation: Orphanet lists hypertelorism as a frequent phenotype.
- target: Posteriorly rotated ears
description: Posteriorly rotated ears are part of the reported congenital phenotype spectrum; the cached evidence does not specify a causal morphogenetic intermediate.
causal_link_type: UNKNOWN
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0000358 | Posteriorly rotated ears | Frequent (79-30%)"
explanation: Orphanet lists posteriorly rotated ears as a frequent phenotype.
- target: Wide nasal bridge
description: Wide nasal bridge is part of the reported congenital phenotype spectrum; the cached evidence does not specify a causal morphogenetic intermediate.
causal_link_type: UNKNOWN
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0000431 | Wide nasal bridge | Frequent (79-30%)"
explanation: Orphanet lists wide nasal bridge as a frequent phenotype.
- target: Downslanted palpebral fissures
description: Downslanted palpebral fissures are part of the reported congenital phenotype spectrum; the cached evidence does not specify a causal morphogenetic intermediate.
causal_link_type: UNKNOWN
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0000494 | Downslanted palpebral fissures | Frequent (79-30%)"
explanation: Orphanet lists downslanted palpebral fissures as a frequent phenotype.
- target: Hip dysplasia
description: Hip dysplasia is part of the reported congenital phenotype spectrum; the cached evidence does not specify a causal morphogenetic intermediate.
causal_link_type: UNKNOWN
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0001385 | Hip dysplasia | Frequent (79-30%)"
explanation: Orphanet lists hip dysplasia as a frequent phenotype.
- target: Patent ductus arteriosus
description: Patent ductus arteriosus is reported in hereditary orotic aciduria, but the cached evidence does not define the cardiac developmental intermediate.
causal_link_type: UNKNOWN
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0001643 | Patent ductus arteriosus | Frequent (79-30%)"
explanation: Orphanet lists patent ductus arteriosus as a frequent phenotype.
- target: Splenomegaly
description: Splenomegaly is reported in hereditary orotic aciduria, but the cached evidence does not define the intermediate.
causal_link_type: UNKNOWN
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0001744 | Splenomegaly | Frequent (79-30%)"
explanation: Orphanet lists splenomegaly as a frequent phenotype.
- target: Abnormal toenail morphology
description: Abnormal toenail morphology is part of the reported congenital phenotype spectrum; the cached evidence does not specify a causal morphogenetic intermediate.
causal_link_type: UNKNOWN
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0008388 | Abnormal toenail morphology | Frequent (79-30%)"
explanation: Orphanet lists abnormal toenail morphology as a frequent phenotype.
- name: T Cell Immunodeficiency
description: >-
Hereditary orotic aciduria can include selective impairment of T-cell
function with relatively intact humoral immunity, explaining recurrent
infections and the Orphanet abnormal T-cell-physiology phenotype.
cell_types:
- preferred_term: T cell
term:
id: CL:0000084
label: T cell
biological_processes:
- preferred_term: T cell mediated immunity
term:
id: GO:0002456
label: T cell mediated immunity
modifier: DECREASED
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "It has been reported that the main immunodeficiency in patients with HOA is the selective impairment in T cell function with intact humoral immunity."
explanation: The case-report discussion supports selective T-cell impairment as the immunodeficiency mechanism.
downstream:
- target: Abnormal T cell physiology
description: Selective T-cell functional impairment corresponds to the abnormal T-cell-physiology phenotype.
causal_link_type: DIRECT
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0011840 | Abnormality of T cell physiology | Frequent (79-30%)"
explanation: Orphanet records abnormal T-cell physiology as a frequent phenotype.
- target: Recurrent respiratory infections
description: Selective cellular immune impairment increases susceptibility to recurrent and severe infections.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "During the first year, she had recurrent, severe infections including disseminated varicella."
explanation: The reported patient had recurrent severe infections in the setting of cellular immunodeficiency.
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0002205 | Recurrent respiratory infections | Frequent (79-30%)"
explanation: Orphanet lists recurrent respiratory infections as a frequent phenotype.
phenotypes:
- name: Global developmental delay
frequency: VERY_FREQUENT
phenotype_term:
preferred_term: Global developmental delay
term:
id: HP:0001263
label: Global developmental delay
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0001263 | Global developmental delay | Very frequent (99-80%)"
explanation: Orphanet lists global developmental delay as a very frequent phenotype.
- name: Anemia
frequency: VERY_FREQUENT
phenotype_term:
preferred_term: Anemia
term:
id: HP:0001903
label: Anemia
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0001903 | Anemia | Very frequent (99-80%)"
explanation: Orphanet lists anemia as a very frequent phenotype.
- name: Megaloblastic anemia
phenotype_term:
preferred_term: Megaloblastic anemia
term:
id: HP:0001889
label: Megaloblastic anemia
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "A rare genetic disorder of pyrimidine metabolism characterized by early onset of megaloblastic anemia"
explanation: Orphanet definition identifies early megaloblastic anemia as a core clinical feature.
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The hallmarks of the disease are a megaloblastic bone marrow that is refractory to hematinic therapy, accompanied by a markedly increased excretion of orotic acid in the urine."
explanation: Human case report and literature summary support megaloblastic marrow as a hallmark.
- name: Oroticaciduria
frequency: VERY_FREQUENT
phenotype_term:
preferred_term: Oroticaciduria
term:
id: HP:0003218
label: Oroticaciduria
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0003218 | Oroticaciduria | Very frequent (99-80%)"
explanation: Orphanet lists oroticaciduria as a very frequent phenotype.
- name: Aminoaciduria
frequency: VERY_FREQUENT
phenotype_term:
preferred_term: Aminoaciduria
term:
id: HP:0003355
label: Aminoaciduria
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0003355 | Aminoaciduria | Very frequent (99-80%)"
explanation: Orphanet lists aminoaciduria as a very frequent phenotype.
- name: Orotic acid crystalluria
frequency: VERY_FREQUENT
phenotype_term:
preferred_term: Orotic acid crystalluria
term:
id: HP:0003526
label: Orotic acid crystalluria
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0003526 | Orotic acid crystalluria | Very frequent (99-80%)"
explanation: Orphanet lists orotic acid crystalluria as a very frequent phenotype.
- name: Failure to thrive
phenotype_term:
preferred_term: Failure to thrive
term:
id: HP:0001508
label: Failure to thrive
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "A rare genetic disorder of pyrimidine metabolism characterized by early onset of megaloblastic anemia, global developmental delay, and failure to thrive"
explanation: Orphanet definition includes failure to thrive among the core clinical features.
- name: Seizure
phenotype_term:
preferred_term: Seizure
term:
id: HP:0001250
label: Seizure
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "Patients without megaloblastic anemia, but with additional manifestations such as epilepsy, have also been reported."
explanation: Orphanet reports epilepsy in a non-megaloblastic presentation.
- reference: PMID:25757096
reference_title: "Hereditary orotic aciduria with epilepsy and without megaloblastic anemia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "This report describes a new case of UMPS deficiency without megaloblastic anemia but with epilepsy."
explanation: Case report directly supports epilepsy as an observed hereditary orotic aciduria manifestation.
- name: Abnormality of the ureter
frequency: FREQUENT
phenotype_term:
preferred_term: Abnormality of the ureter
term:
id: HP:0000069
label: Abnormality of the ureter
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0000069 | Abnormality of the ureter | Frequent (79-30%)"
explanation: Orphanet lists abnormality of the ureter as a frequent phenotype.
- name: Hypertelorism
frequency: FREQUENT
phenotype_term:
preferred_term: Hypertelorism
term:
id: HP:0000316
label: Hypertelorism
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0000316 | Hypertelorism | Frequent (79-30%)"
explanation: Orphanet lists hypertelorism as a frequent phenotype.
- name: Posteriorly rotated ears
frequency: FREQUENT
phenotype_term:
preferred_term: Posteriorly rotated ears
term:
id: HP:0000358
label: Posteriorly rotated ears
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0000358 | Posteriorly rotated ears | Frequent (79-30%)"
explanation: Orphanet lists posteriorly rotated ears as a frequent phenotype.
- name: Wide nasal bridge
frequency: FREQUENT
phenotype_term:
preferred_term: Wide nasal bridge
term:
id: HP:0000431
label: Wide nasal bridge
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0000431 | Wide nasal bridge | Frequent (79-30%)"
explanation: Orphanet lists wide nasal bridge as a frequent phenotype.
- name: Downslanted palpebral fissures
frequency: FREQUENT
phenotype_term:
preferred_term: Downslanted palpebral fissures
term:
id: HP:0000494
label: Downslanted palpebral fissures
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0000494 | Downslanted palpebral fissures | Frequent (79-30%)"
explanation: Orphanet lists downslanted palpebral fissures as a frequent phenotype.
- name: Hip dysplasia
frequency: FREQUENT
phenotype_term:
preferred_term: Hip dysplasia
term:
id: HP:0001385
label: Hip dysplasia
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0001385 | Hip dysplasia | Frequent (79-30%)"
explanation: Orphanet lists hip dysplasia as a frequent phenotype.
- name: Patent ductus arteriosus
frequency: FREQUENT
phenotype_term:
preferred_term: Patent ductus arteriosus
term:
id: HP:0001643
label: Patent ductus arteriosus
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0001643 | Patent ductus arteriosus | Frequent (79-30%)"
explanation: Orphanet lists patent ductus arteriosus as a frequent phenotype.
- name: Splenomegaly
frequency: FREQUENT
phenotype_term:
preferred_term: Splenomegaly
term:
id: HP:0001744
label: Splenomegaly
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0001744 | Splenomegaly | Frequent (79-30%)"
explanation: Orphanet lists splenomegaly as a frequent phenotype.
- name: Recurrent respiratory infections
frequency: FREQUENT
phenotype_term:
preferred_term: Recurrent respiratory infections
term:
id: HP:0002205
label: Recurrent respiratory infections
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0002205 | Recurrent respiratory infections | Frequent (79-30%)"
explanation: Orphanet lists recurrent respiratory infections as a frequent phenotype.
- name: Abnormal toenail morphology
frequency: FREQUENT
phenotype_term:
preferred_term: Abnormal toenail morphology
term:
id: HP:0008388
label: Abnormal toenail morphology
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0008388 | Abnormal toenail morphology | Frequent (79-30%)"
explanation: Orphanet lists abnormal toenail morphology as a frequent phenotype.
- name: Abnormal T cell physiology
frequency: FREQUENT
phenotype_term:
preferred_term: Abnormality of T cell physiology
term:
id: HP:0011840
label: Abnormal T cell physiology
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "HP:0011840 | Abnormality of T cell physiology | Frequent (79-30%)"
explanation: Orphanet lists abnormal T cell physiology as a frequent phenotype.
biochemical:
- name: Elevated urinary orotic acid
presence: INCREASED
context: >-
Massive urinary orotic acid overexcretion is the defining biochemical
signature of the UMPS block and is confirmed by urine organic acid testing.
readouts:
- target: UMP Synthetase Enzymatic Block
relationship: READOUT_OF
direction: POSITIVE
endpoint_context: DIAGNOSTIC
interpretation: >-
Increased urinary orotic acid reports upstream UMPS-dependent pyrimidine
biosynthesis failure and supports biochemical diagnosis.
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "associated with massive urinary overexcretion of orotic acid"
explanation: Orphanet identifies massive urinary orotic acid overexcretion as the disease-defining biomarker.
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Further findings of crystalluria and a significant urinary excretion of orotic acid in our patient (>266.1 mmol/mol creatinine; reference range 0.2–1.5) supported the diagnosis."
explanation: Marked urinary orotic acid elevation supports this biomarker as a diagnostic readout of the UMPS block.
biomarker_term:
preferred_term: orotic acid
term:
id: CHEBI:16742
label: orotic acid
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "associated with massive urinary overexcretion of orotic acid"
explanation: Orphanet definition identifies urinary overexcretion of orotic acid.
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Further findings of crystalluria and a significant urinary excretion of orotic acid in our patient (>266.1 mmol/mol creatinine; reference range 0.2–1.5) supported the diagnosis."
explanation: The reported patient had markedly elevated urinary orotic acid supporting diagnosis.
diagnosis:
- name: Dried blood spot orotic acid newborn screening
description: >-
Expanded newborn screening can detect elevated dried-blood-spot orotic acid
before symptoms develop, followed by confirmatory urine organic acids and
molecular testing.
diagnosis_term:
preferred_term: disease screening
term:
id: MAXO:0000124
label: disease screening
evidence:
- reference: PMID:36999056
reference_title: "Hereditary orotic aciduria identified by newborn screening."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Newborn screening has the potential to identify and enable treatment of affected individuals before they become significantly ill."
explanation: The newborn-screening cohort supports DBS orotic acid as a presymptomatic screening approach.
- reference: PMID:36999056
reference_title: "Hereditary orotic aciduria identified by newborn screening."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Since the addition of orotic acid measurement to the Israeli routine newborn screening program, 1,492,439 neonates have been screened."
explanation: This documents implementation of orotic-acid measurement in routine newborn screening.
- name: Urine organic acid and UMPS molecular confirmation
description: >-
Confirmatory evaluation pairs urinary organic acid testing for orotic
aciduria with molecular testing for biallelic UMPS variants.
diagnosis_term:
preferred_term: molecular genetic testing
term:
id: MAXO:0000533
label: molecular genetic testing
evidence:
- reference: PMID:36999056
reference_title: "Hereditary orotic aciduria identified by newborn screening."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Urine organic acid testing confirmed the presence of orotic aciduria along with homozygous variations in the UMPS gene."
explanation: The newborn-screening cohort used urine organic acids plus UMPS variants for confirmation.
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The analysis demonstrated a previously unreported homozygous pathogenic variant in the UMPS gene (c.1010C > G; A337G) confirming a diagnosis of HOA."
explanation: Case report supports UMPS molecular testing as diagnostic confirmation.
treatments:
- name: Uridine triacetate therapy
description: >-
Uridine triacetate provides uridine nucleoside replacement to bypass the
UMPS-dependent UMP synthesis block and can improve hematologic,
immunologic, growth, seizure, and urinary-orotic-acid abnormalities.
treatment_term:
preferred_term: Pharmacotherapy
term:
id: NCIT:C15986
label: Pharmacotherapy
therapeutic_agent:
- preferred_term: uridine triacetate
term:
id: CHEBI:90914
label: uridine triacetate
target_mechanisms:
- target: UMP Synthetase Enzymatic Block
treatment_effect: BYPASSES
description: Uridine supplementation bypasses the endogenous UMPS block by supplying pyrimidine nucleoside.
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Treatment is performed with the nucleoside uridine."
explanation: Literature discussion supports uridine nucleoside therapy as disease-directed treatment for the UMPS block.
- target: T Cell Immunodeficiency
treatment_effect: RESTORES
description: Uridine triacetate therapy improves the cellular immune abnormality observed in HOA.
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "our patient showed a dramatic increase in her lymphocyte count during therapy with a significant decrease in her susceptibility to infections."
explanation: The treated patient had improved lymphocyte count and reduced infection susceptibility during uridine therapy.
target_phenotypes:
- preferred_term: Megaloblastic anemia
term:
id: HP:0001889
label: Megaloblastic anemia
- preferred_term: Oroticaciduria
term:
id: HP:0003218
label: Oroticaciduria
- preferred_term: Failure to thrive
term:
id: HP:0001508
label: Failure to thrive
- preferred_term: Seizure
term:
id: HP:0001250
label: Seizure
- preferred_term: Abnormality of T cell physiology
term:
id: HP:0011840
label: Abnormal T cell physiology
- preferred_term: Recurrent respiratory infections
term:
id: HP:0002205
label: Recurrent respiratory infections
evidence:
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "She was started on uridine triacetate 2 g once daily (60 mg/kg body weight)."
explanation: The reported patient was treated with uridine triacetate.
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Regular follow-ups showed a clinical, immunologic, hematologic and biochemical response."
explanation: Case follow-up supports multisystem response to uridine triacetate therapy.
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Her growth parameters, including weight and height, improved after starting her on uridine supplements."
explanation: Case follow-up supports growth response during uridine therapy.
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "During therapy, urinary excretion of orotic acid fell gradually (Fig. 1)."
explanation: Case follow-up supports biochemical response in urinary orotic acid excretion.
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Since restarting uridine triacetate, there were no breakthrough seizures reported."
explanation: Case follow-up supports seizure control after restarting uridine triacetate.
- reference: PMID:33489760
reference_title: "Hereditary orotic aciduria (HOA): A novel uridine-5-monophosphate synthase (UMPS) mutation."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Bone marrow after 6 months of therapy showed significant improvement of the previously described megaloblastic changes without dysplasia."
explanation: Case follow-up supports hematologic marrow response during uridine therapy.
genetic:
- name: UMPS pathogenic variants
gene_term:
preferred_term: UMPS
term:
id: hgnc:12563
label: UMPS
inheritance:
- name: Autosomal recessive
evidence:
- reference: ORPHA:30
reference_title: "Hereditary orotic aciduria (Orphanet structured-database record)"
supports: SUPPORT
evidence_source: OTHER
snippet: "UMPS | uridine monophosphate synthetase | hgnc:12563 | Disease-causing germline mutation(s) (loss of function) in"
explanation: Orphanet records UMPS loss-of-function germline variants as disease causing.
This report is retrieval-only and is generated directly from Asta results.
search_papers_by_relevance with snippet_search.