Lowe syndrome

Mendelian MONDO:0010645 Pathograph 10 X-linked genetic disorders Membrane trafficking disorders Renal tubulopathies

Lowe syndrome is a rare X-linked multisystem disorder caused by pathogenic OCRL variants that reduce phosphatidylinositol 4,5-bisphosphate 5-phosphatase activity. The disorder classically presents with congenital cataracts, hypotonia or developmental impairment, and proximal tubular dysfunction. Its dominant mechanistic story is defective phosphoinositide control on endosomal and ciliary membranes, causing abnormal actin remodeling, impaired receptor recycling and endocytosis, and progressive kidney and eye disease.

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1
Inheritance
6
Pathophys.
8
Phenotypes
10
Pathograph
1
Genes
3
Treatments
1
Deep Research
👪

Inheritance

1
X-linked recessive inheritance
Classic Lowe syndrome is inherited as an X-linked recessive disorder caused by pathogenic OCRL variants, with affected male probands and heterozygous carrier mothers typical of the syndrome.
Show evidence (1 reference)
PMID:23389333 SUPPORT Human Clinical
"Lowe syndrome is a rare X-linked recessive hereditary disease caused by mutations of the OCRL gene, which encodes an inositol polyphosphate-5-phosphatase."
Clinical genetics study directly states the inheritance pattern and identifies OCRL as the causal gene.
⚙

Pathophysiology

6
OCRL phosphatidylinositol dephosphorylation defect
Pathogenic OCRL variants reduce the 5-phosphatase activity that normally dephosphorylates phosphatidylinositol 4,5-bisphosphate, shifting phosphoinositide homeostasis on internal membranes.
OCRL link
phosphatidylinositol dephosphorylation link
Downstream
Early endosomal PI(4,5)P2 accumulation
Ciliary PI(4,5)P2 imbalance
Show evidence (1 reference)
PMID:7761412 SUPPORT In Vitro
"These results suggest that OCRL is mainly a lipid phosphatase that may control cellular levels of a critical metabolite, phosphatidylinositol 4,5-bisphosphate."
Foundational biochemical study establishing OCRL as the lipid phosphatase whose deficiency initiates Lowe syndrome pathophysiology.
Early endosomal PI(4,5)P2 accumulation
OCRL loss causes ectopic PI(4,5)P2 accumulation on early endosomes, disturbing endosomal membrane composition.
endosome organization link
early endosome link
Downstream
Endosomal actin polymerization increase
Show evidence (1 reference)
PMID:21971085 SUPPORT In Vitro
"These trafficking defects are caused by ectopic accumulation of PtdIns4,5P(2) in EEs"
Demonstrates that OCRL loss directly produces phosphoinositide accumulation on early endosomes.
Endosomal actin polymerization increase
Excess early-endosomal PI(4,5)P2 promotes abnormal F-actin accumulation and broader actin cytoskeletal instability.
actin filament organization link
early endosome link
Downstream
Receptor recycling defect
Show evidence (2 references)
PMID:21971085 SUPPORT In Vitro
"which in turn induces an N-WASP-dependent increase in endosomal F-actin."
Links the phosphoinositide abnormality to excessive endosomal actin assembly.
PMID:12428211 SUPPORT In Vitro
"we have identified a reproducible cellular abnormality of the actin cytoskeleton in fibroblasts from patients with Lowe syndrome."
Independent patient-cell study shows that OCRL deficiency produces a reproducible actin cytoskeletal defect.
Receptor recycling defect
Abnormal phosphoinositide-actin coupling disrupts clathrin-mediated trafficking and recycling of cargo receptors through endosomes.
receptor-mediated endocytosis link endocytic recycling link
early endosome link
Downstream
Proximal tubular endocytic reabsorption failure
Show evidence (2 references)
PMID:15917292 SUPPORT In Vitro
"These findings suggest a role for OCRL1 in clathrin-mediated trafficking of proteins from endosomes to the TGN and that defects in this pathway might contribute to the Lowe syndrome phenotype."
Establishes OCRL as a regulator of clathrin-dependent endosomal trafficking.
PMID:25107275 SUPPORT In Vitro
"Here we show that OCRL loss in Lowe syndrome patient fibroblasts impacts clathrin-mediated endocytosis and results in an endocytic defect."
Patient-cell study shows that OCRL loss disrupts clathrin-mediated endocytosis itself, not only later sorting steps.
Proximal tubular endocytic reabsorption failure
In proximal tubule epithelial cells, defective OCRL-dependent trafficking reduces megalin recycling and impairs receptor-mediated uptake of filtered low-molecular-weight proteins.
epithelial cell of proximal tubule link
receptor-mediated endocytosis link endocytic recycling link
kidney link
Downstream
Renal tubular dysfunction
Low-molecular-weight proteinuria
Show evidence (2 references)
PMID:21971085 SUPPORT In Vitro
"OCRL depletion impairs the recycling of multiple classes of receptors, including megalin (which mediates protein reabsorption in the kidney) that are retained in engorged EEs."
Directly connects OCRL-dependent trafficking failure to megalin misrecycling in the renal protein-reabsorption pathway.
PMID:25838181 SUPPORT Model Organism
"Here, we show that deficiency in OCRL1 causes a defect in endocytosis in the zebrafish pronephric tubule, a model for the mammalian renal tubule."
In vivo model organism evidence shows that OCRL loss causes a renal tubular endocytic defect.
Ciliary PI(4,5)P2 imbalance
OCRL localizes to primary cilia; disease-associated OCRL loss shortens cilia and increases ciliary PI(4,5)P2, indicating a parallel ciliary phosphoinositide defect.
cilium assembly link
primary cilium link
Downstream
Glaucoma OCRL-dependent ciliary mechanosensation in trabecular meshwork cells is a plausible contributor to pressure dysregulation and glaucoma.
Show evidence (2 references)
PMID:22543976 SUPPORT In Vitro
"Lowe syndrome-associated mutations in OCRL result in shortened cilia and this phenotype can be rescued by the introduction of wild-type OCRL"
Shows that OCRL loss directly perturbs cilium maintenance and that rescue is possible with wild-type OCRL.
PMID:28871046 SUPPORT In Vitro
"Here, we demonstrate that cilia from Lowe syndrome patient fibroblasts exhibit increased levels of PI(4,5)P2 and decreased levels of PI4P."
Demonstrates a specific ciliary phosphoinositide imbalance in Lowe syndrome patient cells.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Lowe syndrome Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

8
Eye 2
Bilateral congenital cataract OBLIGATE Cataract (HP:0000518)
Show evidence (1 reference)
PMID:32340490 SUPPORT Human Clinical
"Of 137 patients, all had bilateral congenital cataracts."
Large ophthalmic survey directly supports bilateral congenital cataracts as an obligate phenotype.
Glaucoma FREQUENT Glaucoma (HP:0000501)
Show evidence (1 reference)
PMID:32340490 SUPPORT Human Clinical
"Glaucoma occurred in 54.7% of patients and affected both eyes in the majority of cases."
Directly supports glaucoma as a frequent ocular complication of Lowe syndrome.
Genitourinary 3
Renal tubular dysfunction Renal tubular dysfunction (HP:0000124)
Show evidence (1 reference)
PMID:18480301 SUPPORT Human Clinical
"Patients with Lowe syndrome do not have renal Fanconi syndrome but a selective proximal tubulopathy, variable in extent and dominated by low molecular weight proteinuria and hypercalciuria, the classical features of Dent disease."
Defines the characteristic renal phenotype as selective proximal tubular dysfunction.
Low-molecular-weight proteinuria OBLIGATE proteinuria (HP:0000093)
Show evidence (1 reference)
PMID:18480301 SUPPORT Human Clinical
"All patients had low molecular weight proteinuria and albuminuria."
Cohort study directly supports low-molecular-weight proteinuria as an obligate renal phenotype.
Chronic kidney disease VERY_FREQUENT Chronic kidney disease (HP:0012622)
Show evidence (1 reference)
PMID:27708066 SUPPORT Human Clinical
"CKD stage II-V was found in 82% of patients, of these 58% and 28% had moderate-to-severe CKD in LS and DD2, respectively."
Large international cohort directly supports chronic kidney disease as a very frequent phenotype in Lowe syndrome.
Musculoskeletal 1
Generalized hypotonia Generalized hypotonia (HP:0001290)
Show evidence (1 reference)
PMID:16722554 SUPPORT Other
"Bilateral cataract and severe hypotonia are present at birth."
Review abstract directly supports congenital severe hypotonia as a defining early neurologic feature.
Nervous System 1
Global developmental delay Global developmental delay (HP:0001263)
Show evidence (1 reference)
PMID:35803701 SUPPORT Human Clinical
"Additional features were dental problems (n=77, 56%), bone fractures (n=63, 46%), hypophosphataemia (n=60, 44%), developmental delay and behavioural issues."
Large family-survey cohort supports developmental delay as part of the clinical phenotype.
Other 1
Hypercalciuria VERY_FREQUENT Hypercalciuria (HP:0002150)
Show evidence (1 reference)
PMID:18480301 SUPPORT Human Clinical
"Fifteen patients had hypercalciuria, and 14 aminoaciduria."
Supports hypercalciuria as a very frequent renal manifestation in the reported cohort.
🧬

Genetic Associations

1
OCRL pathogenic variants (Loss-of-function)
Show evidence (3 references)
PMID:25480730 SUPPORT Human Clinical
"All patients carried OCRL gene defects with mutational hot spots at CpG dinucleotides."
Multicenter clinical cohort confirms OCRL defects in all genetically characterized Lowe syndrome patients.
PMID:34586410 SUPPORT Human Clinical
"Truncating mutations in OCRL exons 1-7 lead to Dent disease-2, whereas those in exons 8-24 lead to Lowe syndrome."
Supports disease framing at the severe syndromic end of an OCRL allelic continuum and informs splitting from Dent disease-2.
CGGV:assertion_5140c756-fac0-435b-8f59-a5d4a0b0adb3-2020-07-10T160000.000Z SUPPORT Other
"OCRL | HGNC:8108 | oculocerebrorenal syndrome | MONDO:0010645 | XL | Definitive"
ClinGen classifies the OCRL-oculocerebrorenal syndrome gene-disease relationship as definitive with X-linked inheritance.
💊

Treatments

3
Cataract extraction
Action: surgical procedure MAXO:0000004
Early cataract surgery is part of standard management to clear the visual axis in affected infants.
Show evidence (2 references)
PMID:16722554 SUPPORT Other
"The treatment includes: cataract extraction, glaucoma control, physical and speech therapy, use of drugs to address behavioural problems, and correction of the tubular acidosis and the bone disease with the use of bicarbonate, phosphate, potassium and water."
Review abstract lists cataract extraction as standard treatment in Lowe syndrome.
PMID:35847784 SUPPORT Human Clinical
"During postoperative one-and-a-half-year follow-up, the boy exhibited an improved visual acuity and a well-controlled IOP without the use of topical IOP-lowering medications."
Case report supports clinical benefit from cataract surgery combined with glaucoma surgery in an infant with Lowe syndrome.
Glaucoma surgery
Action: surgical procedure MAXO:0000004
Surgical pressure-lowering procedures are frequently required for glaucoma, with aqueous tube shunts performing well in retrospective survey data.
Show evidence (2 references)
PMID:32340490 SUPPORT Human Clinical
"Although trabeculectomy and goniotomy are commonly used for pressure management, aqueous tube shunts had the best outcomes."
Retrospective ophthalmic survey identifies glaucoma surgery approaches used in practice and highlights the best reported outcomes.
PMID:35847784 SUPPORT Human Clinical
"We recommend combined cataract surgery and minimally invasive glaucoma surgery (MIGS) as a safe, feasible, and efficient method to treat congenital cataract and glaucoma in Lowe syndrome patients."
Case report provides direct procedural evidence for combined surgical glaucoma control in Lowe syndrome.
Renal tubular loss replacement
Action: supportive care MAXO:0000950
Supportive replacement of bicarbonate, phosphate, potassium, water, and related losses is used to correct tubular acidosis and bone disease.
Show evidence (2 references)
PMID:16722554 SUPPORT Other
"The treatment includes: cataract extraction, glaucoma control, physical and speech therapy, use of drugs to address behavioural problems, and correction of the tubular acidosis and the bone disease with the use of bicarbonate, phosphate, potassium and water."
Review abstract summarizes the standard supportive replacement strategy for renal tubular and skeletal complications.
PMID:18480301 SUPPORT Human Clinical
"Seven patients required bicarbonate and three required phosphate replacement; all others maintained normal serum values without supplementation."
Cohort data show real-world use of bicarbonate and phosphate replacement for clinically significant tubular losses.
{ }

Source YAML

click to show 
name: Lowe syndrome
creation_date: '2026-04-13T01:18:21Z'
updated_date: '2026-04-13T01:18:21Z'
category: Mendelian
synonyms:
- oculocerebrorenal syndrome of Lowe
- oculocerebrorenal syndrome
- Lowe oculocerebrorenal syndrome
disease_term:
  preferred_term: Lowe syndrome
  term:
    id: MONDO:0010645
    label: oculocerebrorenal syndrome
parents:
- X-linked genetic disorders
- Membrane trafficking disorders
- Renal tubulopathies
description: >-
  Lowe syndrome is a rare X-linked multisystem disorder caused by pathogenic
  OCRL variants that reduce phosphatidylinositol 4,5-bisphosphate 5-phosphatase
  activity. The disorder classically presents with congenital cataracts,
  hypotonia or developmental impairment, and proximal tubular dysfunction. Its
  dominant mechanistic story is defective phosphoinositide control on endosomal
  and ciliary membranes, causing abnormal actin remodeling, impaired receptor
  recycling and endocytosis, and progressive kidney and eye disease.
prevalence:
- population: General population
  percentage: 1 in 500,000
  notes: >-
    Lowe syndrome is ultra-rare, panethnic, and consistently described as
    affecting roughly one child per 500,000.
  evidence:
  - reference: PMID:16722554
    reference_title: "Lowe syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "It is a uncommon, panethnic, X-linked disease, with estimated prevalence in the general population of approximately 1 in 500,000."
    explanation: Review article providing the classic prevalence estimate and panethnic disease framing.
  - reference: PMID:35803701
    reference_title: "Endocrine and behavioural features of Lowe syndrome and their potential molecular mechanisms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Lowe syndrome (LS) is an X linked disease caused by pathogenic variants in the OCRL gene that impacts approximately 1 in 500 000 children."
    explanation: Large family-survey study independently supports the same approximate prevalence in affected children.
inheritance:
- name: X-linked recessive inheritance
  description: >-
    Classic Lowe syndrome is inherited as an X-linked recessive disorder caused
    by pathogenic OCRL variants, with affected male probands and heterozygous
    carrier mothers typical of the syndrome.
  evidence:
  - reference: PMID:23389333
    reference_title: "Novel OCRL mutations in Chinese children with Lowe syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Lowe syndrome is a rare X-linked recessive hereditary disease caused by mutations of the OCRL gene, which encodes an inositol polyphosphate-5-phosphatase."
    explanation: Clinical genetics study directly states the inheritance pattern and identifies OCRL as the causal gene.
progression:
- phase: Congenital ocular and neurologic onset
  age_range: Birth to early infancy
  notes: >-
    Dense congenital cataracts and severe hypotonia are typically present at
    birth, while proximal tubular dysfunction becomes clinically evident during
    the first weeks to months of life.
  evidence:
  - reference: PMID:16722554
    reference_title: "Lowe syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Bilateral cataract and severe hypotonia are present at birth. In the subsequent weeks or months, a proximal renal tubulopathy (Fanconi-type) becomes evident and the ocular picture may be complicated by glaucoma and cheloids."
    explanation: Review abstract directly summarizes the characteristic sequence of congenital eye and neurologic signs followed by early renal disease.
- phase: Progressive kidney disease
  notes: >-
    Chronic kidney disease is common in children with Lowe syndrome and
    progresses faster than in OCRL-related Dent disease-2.
  evidence:
  - reference: PMID:27708066
    reference_title: "Long-term renal outcome in children with OCRL mutations: retrospective analysis of a large international cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "CKD stage II-V was found in 82% of patients, of these 58% and 28% had moderate-to-severe CKD in LS and DD2, respectively."
    explanation: Large international cohort study shows chronic kidney disease is already common in childhood Lowe syndrome.
  - reference: PMID:27708066
    reference_title: "Long-term renal outcome in children with OCRL mutations: retrospective analysis of a large international cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Survival analysis showed that LS was also associated with a faster CKD progression than DD2 (P < 0.01)."
    explanation: Demonstrates that the Lowe syndrome renal phenotype progresses more rapidly than the related Dent disease-2 phenotype.
genetic:
- name: OCRL pathogenic variants
  gene_term:
    preferred_term: OCRL
    term:
      id: hgnc:8108
      label: OCRL
  association: Loss-of-function
  presence: Positive
  notes: >-
    Disease-causing alleles include missense, nonsense, frameshift, splice-site,
    and deletion variants. Classic Lowe syndrome is usually associated with more
    severe OCRL loss of function, whereas some N-terminal truncating variants
    preserve an exon-8-starting OCRL isoform and are more likely to produce the
    milder Dent disease-2 phenotype.
  evidence:
  - reference: PMID:25480730
    reference_title: "Characterization of 28 novel patients expands the mutational and phenotypic spectrum of Lowe syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients carried OCRL gene defects with mutational hot spots at CpG dinucleotides."
    explanation: Multicenter clinical cohort confirms OCRL defects in all genetically characterized Lowe syndrome patients.
  - reference: PMID:34586410
    reference_title: "Identification of novel OCRL isoforms associated with phenotypic differences between Dent disease-2 and Lowe syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Truncating mutations in OCRL exons 1-7 lead to Dent disease-2, whereas those in exons 8-24 lead to Lowe syndrome."
    explanation: Supports disease framing at the severe syndromic end of an OCRL allelic continuum and informs splitting from Dent disease-2.
  - reference: CGGV:assertion_5140c756-fac0-435b-8f59-a5d4a0b0adb3-2020-07-10T160000.000Z
    reference_title: "OCRL / oculocerebrorenal syndrome (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "OCRL | HGNC:8108 | oculocerebrorenal syndrome | MONDO:0010645 | XL | Definitive"
    explanation: ClinGen classifies the OCRL-oculocerebrorenal syndrome gene-disease relationship as definitive with X-linked inheritance.
pathophysiology:
- name: OCRL phosphatidylinositol dephosphorylation defect
  description: >-
    Pathogenic OCRL variants reduce the 5-phosphatase activity that normally
    dephosphorylates phosphatidylinositol 4,5-bisphosphate, shifting
    phosphoinositide homeostasis on internal membranes.
  genes:
  - preferred_term: OCRL
    term:
      id: hgnc:8108
      label: OCRL
  biological_processes:
  - preferred_term: phosphatidylinositol dephosphorylation
    term:
      id: GO:0046856
      label: phosphatidylinositol dephosphorylation
  evidence:
  - reference: PMID:7761412
    reference_title: "The protein deficient in Lowe syndrome is a phosphatidylinositol-4,5-bisphosphate 5-phosphatase."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "These results suggest that OCRL is mainly a lipid phosphatase that may control cellular levels of a critical metabolite, phosphatidylinositol 4,5-bisphosphate."
    explanation: Foundational biochemical study establishing OCRL as the lipid phosphatase whose deficiency initiates Lowe syndrome pathophysiology.
  downstream:
  - target: Early endosomal PI(4,5)P2 accumulation
  - target: Ciliary PI(4,5)P2 imbalance

- name: Early endosomal PI(4,5)P2 accumulation
  description: >-
    OCRL loss causes ectopic PI(4,5)P2 accumulation on early endosomes,
    disturbing endosomal membrane composition.
  cellular_components:
  - preferred_term: early endosome
    term:
      id: GO:0005769
      label: early endosome
  biological_processes:
  - preferred_term: endosome organization
    term:
      id: GO:0007032
      label: endosome organization
  evidence:
  - reference: PMID:21971085
    reference_title: "OCRL controls trafficking through early endosomes via PtdIns4,5P₂-dependent regulation of endosomal actin."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "These trafficking defects are caused by ectopic accumulation of PtdIns4,5P(2) in EEs"
    explanation: Demonstrates that OCRL loss directly produces phosphoinositide accumulation on early endosomes.
  downstream:
  - target: Endosomal actin polymerization increase

- name: Endosomal actin polymerization increase
  description: >-
    Excess early-endosomal PI(4,5)P2 promotes abnormal F-actin accumulation and
    broader actin cytoskeletal instability.
  cellular_components:
  - preferred_term: early endosome
    term:
      id: GO:0005769
      label: early endosome
  biological_processes:
  - preferred_term: actin filament organization
    term:
      id: GO:0007015
      label: actin filament organization
  evidence:
  - reference: PMID:21971085
    reference_title: "OCRL controls trafficking through early endosomes via PtdIns4,5P₂-dependent regulation of endosomal actin."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "which in turn induces an N-WASP-dependent increase in endosomal F-actin."
    explanation: Links the phosphoinositide abnormality to excessive endosomal actin assembly.
  - reference: PMID:12428211
    reference_title: "The deficiency of PIP2 5-phosphatase in Lowe syndrome affects actin polymerization."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "we have identified a reproducible cellular abnormality of the actin cytoskeleton in fibroblasts from patients with Lowe syndrome."
    explanation: Independent patient-cell study shows that OCRL deficiency produces a reproducible actin cytoskeletal defect.
  downstream:
  - target: Receptor recycling defect

- name: Receptor recycling defect
  description: >-
    Abnormal phosphoinositide-actin coupling disrupts clathrin-mediated
    trafficking and recycling of cargo receptors through endosomes.
  cellular_components:
  - preferred_term: early endosome
    term:
      id: GO:0005769
      label: early endosome
  biological_processes:
  - preferred_term: receptor-mediated endocytosis
    term:
      id: GO:0006898
      label: receptor-mediated endocytosis
  - preferred_term: endocytic recycling
    term:
      id: GO:0032456
      label: endocytic recycling
  evidence:
  - reference: PMID:15917292
    reference_title: "Lowe syndrome protein OCRL1 interacts with clathrin and regulates protein trafficking between endosomes and the trans-Golgi network."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "These findings suggest a role for OCRL1 in clathrin-mediated trafficking of proteins from endosomes to the TGN and that defects in this pathway might contribute to the Lowe syndrome phenotype."
    explanation: Establishes OCRL as a regulator of clathrin-dependent endosomal trafficking.
  - reference: PMID:25107275
    reference_title: "A role of OCRL in clathrin-coated pit dynamics and uncoating revealed by studies of Lowe syndrome cells."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Here we show that OCRL loss in Lowe syndrome patient fibroblasts impacts clathrin-mediated endocytosis and results in an endocytic defect."
    explanation: Patient-cell study shows that OCRL loss disrupts clathrin-mediated endocytosis itself, not only later sorting steps.
  downstream:
  - target: Proximal tubular endocytic reabsorption failure

- name: Proximal tubular endocytic reabsorption failure
  description: >-
    In proximal tubule epithelial cells, defective OCRL-dependent trafficking
    reduces megalin recycling and impairs receptor-mediated uptake of filtered
    low-molecular-weight proteins.
  cell_types:
  - preferred_term: epithelial cell of proximal tubule
    term:
      id: CL:0002306
      label: epithelial cell of proximal tubule
  locations:
  - preferred_term: kidney
    term:
      id: UBERON:0002113
      label: kidney
  biological_processes:
  - preferred_term: receptor-mediated endocytosis
    term:
      id: GO:0006898
      label: receptor-mediated endocytosis
  - preferred_term: endocytic recycling
    term:
      id: GO:0032456
      label: endocytic recycling
  evidence:
  - reference: PMID:21971085
    reference_title: "OCRL controls trafficking through early endosomes via PtdIns4,5P₂-dependent regulation of endosomal actin."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "OCRL depletion impairs the recycling of multiple classes of receptors, including megalin (which mediates protein reabsorption in the kidney) that are retained in engorged EEs."
    explanation: Directly connects OCRL-dependent trafficking failure to megalin misrecycling in the renal protein-reabsorption pathway.
  - reference: PMID:25838181
    reference_title: "The Lowe syndrome protein OCRL1 is required for endocytosis in the zebrafish pronephric tubule."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Here, we show that deficiency in OCRL1 causes a defect in endocytosis in the zebrafish pronephric tubule, a model for the mammalian renal tubule."
    explanation: In vivo model organism evidence shows that OCRL loss causes a renal tubular endocytic defect.
  downstream:
  - target: Renal tubular dysfunction
  - target: Low-molecular-weight proteinuria

- name: Ciliary PI(4,5)P2 imbalance
  description: >-
    OCRL localizes to primary cilia; disease-associated OCRL loss shortens cilia
    and increases ciliary PI(4,5)P2, indicating a parallel ciliary
    phosphoinositide defect.
  cellular_components:
  - preferred_term: primary cilium
    term:
      id: GO:0005929
      label: cilium
  biological_processes:
  - preferred_term: cilium assembly
    term:
      id: GO:0060271
      label: cilium assembly
  evidence:
  - reference: PMID:22543976
    reference_title: "OCRL localizes to the primary cilium: a new role for cilia in Lowe syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Lowe syndrome-associated mutations in OCRL result in shortened cilia and this phenotype can be rescued by the introduction of wild-type OCRL"
    explanation: Shows that OCRL loss directly perturbs cilium maintenance and that rescue is possible with wild-type OCRL.
  - reference: PMID:28871046
    reference_title: "Loss of OCRL increases ciliary PI(4,5)P(2) in Lowe oculocerebrorenal syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Here, we demonstrate that cilia from Lowe syndrome patient fibroblasts exhibit increased levels of PI(4,5)P2 and decreased levels of PI4P."
    explanation: Demonstrates a specific ciliary phosphoinositide imbalance in Lowe syndrome patient cells.
  downstream:
  - target: Glaucoma
    description: >-
      OCRL-dependent ciliary mechanosensation in trabecular meshwork cells is a
      plausible contributor to pressure dysregulation and glaucoma.
    evidence:
    - reference: PMID:25143588
      reference_title: "Primary cilia signaling mediates intraocular pressure sensation."
      supports: PARTIAL
      evidence_source: IN_VITRO
      snippet: "Furthermore, OCRL is found to be required for primary cilia to respond to pressure stimulation."
      explanation: Supports a ciliary mechanosensory mechanism that plausibly links OCRL dysfunction to glaucoma in Lowe syndrome.
phenotypes:
- name: Bilateral congenital cataract
  category: Ophthalmologic
  description: >-
    Dense bilateral lens opacities are present from birth and are the most
    consistent ophthalmic finding in classic Lowe syndrome.
  frequency: OBLIGATE
  phenotype_term:
    preferred_term: Congenital cataract
    term:
      id: HP:0000518
      label: Cataract
  evidence:
  - reference: PMID:32340490
    reference_title: "Oculocerebrorenal syndrome of Lowe: Survey of ophthalmic presentations and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Of 137 patients, all had bilateral congenital cataracts."
    explanation: Large ophthalmic survey directly supports bilateral congenital cataracts as an obligate phenotype.

- name: Glaucoma
  category: Ophthalmologic
  description: >-
    Glaucoma is common, may be present concurrently with cataracts or develop
    after cataract surgery, and is a major cause of vision loss.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Glaucoma
    term:
      id: HP:0000501
      label: Glaucoma
  evidence:
  - reference: PMID:32340490
    reference_title: "Oculocerebrorenal syndrome of Lowe: Survey of ophthalmic presentations and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Glaucoma occurred in 54.7% of patients and affected both eyes in the majority of cases."
    explanation: Directly supports glaucoma as a frequent ocular complication of Lowe syndrome.

- name: Generalized hypotonia
  category: Neurologic
  description: >-
    Marked hypotonia is typically present from birth and is part of the
    canonical neonatal presentation.
  phenotype_term:
    preferred_term: Generalized hypotonia
    term:
      id: HP:0001290
      label: Generalized hypotonia
  evidence:
  - reference: PMID:16722554
    reference_title: "Lowe syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Bilateral cataract and severe hypotonia are present at birth."
    explanation: Review abstract directly supports congenital severe hypotonia as a defining early neurologic feature.

- name: Global developmental delay
  category: Developmental
  description: >-
    Developmental delay emerges in childhood and contributes to the
    neurobehavioral syndrome.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: PMID:35803701
    reference_title: "Endocrine and behavioural features of Lowe syndrome and their potential molecular mechanisms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Additional features were dental problems (n=77, 56%), bone fractures (n=63, 46%), hypophosphataemia (n=60, 44%), developmental delay and behavioural issues."
    explanation: Large family-survey cohort supports developmental delay as part of the clinical phenotype.

- name: Renal tubular dysfunction
  category: Renal
  description: >-
    The renal phenotype is a selective proximal tubulopathy rather than a fully
    expressed generalized Fanconi syndrome in all patients.
  phenotype_term:
    preferred_term: Proximal renal tubulopathy
    term:
      id: HP:0000124
      label: Renal tubular dysfunction
  evidence:
  - reference: PMID:18480301
    reference_title: "Renal phenotype in Lowe Syndrome: a selective proximal tubular dysfunction."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with Lowe syndrome do not have renal Fanconi syndrome but a selective proximal tubulopathy, variable in extent and dominated by low molecular weight proteinuria and hypercalciuria, the classical features of Dent disease."
    explanation: Defines the characteristic renal phenotype as selective proximal tubular dysfunction.

- name: Low-molecular-weight proteinuria
  category: Renal
  description: >-
    Low-molecular-weight proteinuria is the dominant protein-reabsorption defect
    of the renal phenotype.
  frequency: OBLIGATE
  phenotype_term:
    preferred_term: Low-molecular-weight proteinuria
    term:
      id: HP:0000093
      label: proteinuria
  evidence:
  - reference: PMID:18480301
    reference_title: "Renal phenotype in Lowe Syndrome: a selective proximal tubular dysfunction."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients had low molecular weight proteinuria and albuminuria."
    explanation: Cohort study directly supports low-molecular-weight proteinuria as an obligate renal phenotype.

- name: Hypercalciuria
  category: Renal
  description: >-
    Hypercalciuria is a very common component of the proximal tubular phenotype.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Hypercalciuria
    term:
      id: HP:0002150
      label: Hypercalciuria
  evidence:
  - reference: PMID:18480301
    reference_title: "Renal phenotype in Lowe Syndrome: a selective proximal tubular dysfunction."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Fifteen patients had hypercalciuria, and 14 aminoaciduria."
    explanation: Supports hypercalciuria as a very frequent renal manifestation in the reported cohort.

- name: Chronic kidney disease
  category: Renal
  description: >-
    Chronic kidney disease develops progressively during childhood and
    adolescence, with faster decline than in OCRL-related Dent disease-2.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Chronic kidney disease
    term:
      id: HP:0012622
      label: Chronic kidney disease
  evidence:
  - reference: PMID:27708066
    reference_title: "Long-term renal outcome in children with OCRL mutations: retrospective analysis of a large international cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "CKD stage II-V was found in 82% of patients, of these 58% and 28% had moderate-to-severe CKD in LS and DD2, respectively."
    explanation: Large international cohort directly supports chronic kidney disease as a very frequent phenotype in Lowe syndrome.
treatments:
- name: Cataract extraction
  description: >-
    Early cataract surgery is part of standard management to clear the visual
    axis in affected infants.
  treatment_term:
    preferred_term: surgical procedure
    term:
      id: MAXO:0000004
      label: surgical procedure
  evidence:
  - reference: PMID:16722554
    reference_title: "Lowe syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The treatment includes: cataract extraction, glaucoma control, physical and speech therapy, use of drugs to address behavioural problems, and correction of the tubular acidosis and the bone disease with the use of bicarbonate, phosphate, potassium and water."
    explanation: Review abstract lists cataract extraction as standard treatment in Lowe syndrome.
  - reference: PMID:35847784
    reference_title: "Case Report: Combined Cataract Surgery and Minimally Invasive Glaucoma Surgery Provide an Alternative Treatment Approach for Lowe Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "During postoperative one-and-a-half-year follow-up, the boy exhibited an improved visual acuity and a well-controlled IOP without the use of topical IOP-lowering medications."
    explanation: Case report supports clinical benefit from cataract surgery combined with glaucoma surgery in an infant with Lowe syndrome.

- name: Glaucoma surgery
  description: >-
    Surgical pressure-lowering procedures are frequently required for glaucoma,
    with aqueous tube shunts performing well in retrospective survey data.
  treatment_term:
    preferred_term: surgical procedure
    term:
      id: MAXO:0000004
      label: surgical procedure
  evidence:
  - reference: PMID:32340490
    reference_title: "Oculocerebrorenal syndrome of Lowe: Survey of ophthalmic presentations and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although trabeculectomy and goniotomy are commonly used for pressure management, aqueous tube shunts had the best outcomes."
    explanation: Retrospective ophthalmic survey identifies glaucoma surgery approaches used in practice and highlights the best reported outcomes.
  - reference: PMID:35847784
    reference_title: "Case Report: Combined Cataract Surgery and Minimally Invasive Glaucoma Surgery Provide an Alternative Treatment Approach for Lowe Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend combined cataract surgery and minimally invasive glaucoma surgery (MIGS) as a safe, feasible, and efficient method to treat congenital cataract and glaucoma in Lowe syndrome patients."
    explanation: Case report provides direct procedural evidence for combined surgical glaucoma control in Lowe syndrome.

- name: Renal tubular loss replacement
  description: >-
    Supportive replacement of bicarbonate, phosphate, potassium, water, and
    related losses is used to correct tubular acidosis and bone disease.
  treatment_term:
    preferred_term: supportive care
    term:
      id: MAXO:0000950
      label: supportive care
  evidence:
  - reference: PMID:16722554
    reference_title: "Lowe syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The treatment includes: cataract extraction, glaucoma control, physical and speech therapy, use of drugs to address behavioural problems, and correction of the tubular acidosis and the bone disease with the use of bicarbonate, phosphate, potassium and water."
    explanation: Review abstract summarizes the standard supportive replacement strategy for renal tubular and skeletal complications.
  - reference: PMID:18480301
    reference_title: "Renal phenotype in Lowe Syndrome: a selective proximal tubular dysfunction."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Seven patients required bicarbonate and three required phosphate replacement; all others maintained normal serum values without supplementation."
    explanation: Cohort data show real-world use of bicarbonate and phosphate replacement for clinically significant tubular losses.
notes: >-
  This entry is framed to classic syndromic OCRL-related oculocerebrorenal
  syndrome rather than to the broader OCRL-related disease spectrum. OCRL-related
  Dent disease-2 shares the proximal-tubule endocytic mechanism, but genotype-
  phenotype studies support keeping Lowe syndrome curated as the more severe
  multisystem disease entity recognized by MONDO.
📚

References & Deep Research

Deep Research

1
Deep Research Summary: Lowe Syndrome ▸

Deep Research Summary: Lowe Syndrome

Research Method

Manual disease curation performed on 2026-04-12 to 2026-04-13 using PubMed, MONDO/OAK term lookup, and local dismech validation workflows.

Primary goals: - frame the disease correctly against the broader OCRL-related spectrum - keep the mechanistic graph atomic rather than bundled - prefer PMID-backed primary studies for the YAML evidence items - use review papers mainly for prevalence, progression, and standard-of-care summaries

Disease Framing

This curation is intentionally for classic Lowe syndrome / oculocerebrorenal syndrome (MONDO:0010645), not for a lumped "OCRL-related disorder" entry.

Reasons for splitting from Dent disease-2 at the disease level: - PMID:25480730 describes Lowe syndrome as a rare X-linked multisystem disorder "almost always characterized by the triad of congenital cataract, cognitive and behavioral impairment and a proximal tubulopathy." - PMID:18480301 shows that the renal phenotype overlaps strongly with Dent disease, especially low-molecular-weight proteinuria and hypercalciuria. - PMID:34586410 provides a mechanistic explanation for part of the allelic split: truncating variants in exons 1-7 can preserve an OCRL isoform and are more associated with Dent disease-2, whereas truncating variants in exons 8-24 are associated with classic Lowe syndrome.

Working curation choice: - keep Lowe syndrome as the severe syndromic OCRL disease - explicitly note the OCRL allelic continuum in genetic.notes and notes - prioritize mechanistic edges that are shared across the OCRL spectrum only when they plausibly explain the syndromic Lowe phenotype

Main Mechanistic Story

The most coherent disease-level mechanism is:

  1. OCRL loss reduces phosphatidylinositol 4,5-bisphosphate 5-phosphatase activity.
  2. PI(4,5)P2 accumulates abnormally on early endosomes.
  3. Excess endosomal PI(4,5)P2 drives abnormal F-actin assembly.
  4. Endosomal and clathrin-mediated receptor recycling become defective.
  5. In proximal tubule cells this disrupts megalin-dependent reabsorption and produces the dominant renal phenotype.
  6. In parallel, OCRL loss alters ciliary phosphoinositides and cilium maintenance, plausibly contributing to eye disease, especially glaucoma.

Key papers anchoring those nodes: - PMID:7761412 foundational biochemical identification of OCRL as a phosphatidylinositol 4,5-bisphosphate 5-phosphatase. - PMID:21971085 strongest single paper for the endosomal PI(4,5)P2 -> endosomal actin -> megalin recycling story. - PMID:15917292 and PMID:25107275 support clathrin-dependent trafficking and endocytosis defects as distinct atomic steps. - PMID:25838181 gives in vivo renal support in zebrafish and identifies PIP5K suppression as a mechanistically interesting therapeutic direction. - PMID:22543976 and PMID:28871046 support the ciliary branch of disease. - PMID:25143588 supports the specific glaucoma-relevant hypothesis that OCRL is required for pressure-responsive ciliary signaling in trabecular meshwork cells.

Why Some Mechanisms Were Excluded

Several OCRL-adjacent processes were considered but not promoted into the YAML graph because the disease-level support was weaker or too indirect: - lysosome positioning / mTORC1 nutrient sensing - generalized Golgi dysfunction without a clean disease link - broad "ciliopathy" labeling of Lowe syndrome as a parent category - bundled "endolysosomal dysfunction" nodes that mix phosphoinositides, actin, trafficking, and organ phenotypes in one statement

The curation instead keeps those processes decomposed into smaller nodes that are better supported by the abstracts and more reusable across related disorders.

Clinical Phenotype Prioritization

Phenotypes retained in the YAML were limited to well-supported, central disease features: - bilateral congenital cataract - glaucoma - generalized hypotonia - global developmental delay - renal tubular dysfunction - low-molecular-weight proteinuria - hypercalciuria - chronic kidney disease

Why these were prioritized: - PMID:32340490 provides quantitative ophthalmic data in 137 affected individuals, including 100% bilateral congenital cataract and 54.7% glaucoma. - PMID:18480301 gives the clearest quantitative renal phenotype data for low-molecular-weight proteinuria and hypercalciuria. - PMID:27708066 establishes CKD burden and faster progression in Lowe syndrome versus Dent disease-2. - PMID:16722554 is still useful for the classic onset sequence and treatment overview despite being a review.

Phenotypes reviewed but not promoted into the YAML: - short stature - undescended testes - dental problems - fractures / hypophosphatemia - thrombocytopenia - hyperacusis / hyperosmia

These are real and supported in the literature, especially PMID:35803701 and PMID:25480730, but they were treated as secondary modifiers rather than core disease-defining phenotypes for this first-pass disease entry.

Treatment Curation Decisions

The entry keeps treatment claims conservative and symptom-focused: - cataract extraction - glaucoma surgery - renal tubular loss replacement / supportive care

Reasons: - PMID:16722554 gives the most compact standard-of-care summary. - PMID:32340490 provides practical retrospective evidence for glaucoma procedures, with aqueous tube shunts noted as the best-performing approach in that dataset. - PMID:35847784 adds direct infant case evidence for combined cataract and minimally invasive glaucoma surgery. - PMID:18480301 supports bicarbonate and phosphate replacement as real-world supportive treatment for tubular losses.

What was not added: - experimental PIP5K-targeted therapy - broad developmental/behavioral therapies as separate treatment nodes

Those are worth tracking, but the current evidence base is thinner or more indirect than the surgical and renal-supportive measures above.

Evidence Source Choices

Evidence source assignments in the YAML were chosen by study design, not by how the curation was performed: - HUMAN_CLINICAL: cohort studies, retrospective surveys, case reports with direct patient data - IN_VITRO: patient fibroblasts, cultured cells, biochemical assays - MODEL_ORGANISM: zebrafish renal and ciliary studies - OTHER: review articles used only for prevalence / progression / management summaries when cleaner primary abstract text was not available

Notable examples: - PMID:16722554 is tagged OTHER because it is a review article. - PMID:21971085 is tagged IN_VITRO because the supporting claims come from cell-based mechanistic work. - PMID:25838181 is tagged MODEL_ORGANISM because the renal mechanism support comes from zebrafish.

References Used in the YAML

  • PMID:16722554
  • PMID:18480301
  • PMID:21971085
  • PMID:22543976
  • PMID:23389333
  • PMID:25107275
  • PMID:25143588
  • PMID:25480730
  • PMID:25838181
  • PMID:27708066
  • PMID:28871046
  • PMID:32340490
  • PMID:34586410
  • PMID:35803701
  • PMID:35847784
  • PMID:7761412

Validation Plan

Targeted checks planned for this curation: - just validate kb/disorders/Lowe_Syndrome.yaml - just validate-references kb/disorders/Lowe_Syndrome.yaml - just validate-terms-file kb/disorders/Lowe_Syndrome.yaml

If term or reference validation fails, fix the YAML rather than weakening the evidence claims.