Autosomal Recessive Osteopetrosis Type 2

Mendelian MONDO:0009816 Pathograph 4 Sclerosing Bone Dysplasias

Autosomal recessive osteopetrosis type 2 (ARO2) is a severe sclerosing bone disease caused by biallelic loss-of-function mutations in TCIRG1, encoding the osteoclast-specific a3 subunit of the vacuolar H+-ATPase. TCIRG1 mutations are the most frequent cause of infantile malignant osteopetrosis, accounting for over 50% of ARO cases. Osteoclasts are present in normal or elevated numbers but are non-functional due to inability to acidify the resorption lacuna. The disease is characterized by dense but brittle bones, bone marrow failure, cranial nerve compression, and hepatosplenomegaly. Without hematopoietic stem cell transplantation, the disease is fatal within the first decade of life.

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👪

Inheritance

Autosomal Recessive

Autosomal recessive inheritance. Biallelic (homozygous or compound heterozygous) TCIRG1 mutations.

Show evidence (1 reference)

PMID:10888887 PARTIAL

"TCIRG1, encoding the osteoclast-specific 116-kD subunit of the vacuolar proton pump, is mutated in five of nine patients with a diagnosis of infantile malignant osteopetrosis"

TCIRG1 mutations identified as a frequent cause of autosomal recessive osteopetrosis.

⚙

Pathophysiology

Vacuolar Proton Pump Deficiency in Osteoclasts

TCIRG1 encodes the a3 subunit of the vacuolar H+-ATPase (V-ATPase), which is specifically expressed in osteoclasts and essential for proton secretion into the resorption lacuna. Loss-of-function mutations abolish osteoclast acidification capacity, preventing dissolution of hydroxyapatite mineral in bone matrix. Osteoclasts differentiate normally and are present in normal or elevated numbers but cannot resorb bone.

Osteoclast link

Bone Resorption link

Downstream

Progressive Skeletal Sclerosis Loss of osteoclast proton-pump function prevents normal bone resorption and drives skeletal sclerosis.

Show evidence (2 references)

PMID:10888887 PARTIAL

"TCIRG1, encoding the osteoclast-specific 116-kD subunit of the vacuolar proton pump, is mutated in five of nine patients"

Identifies TCIRG1 and the vacuolar proton pump as the pathogenic target.

PMID:10888887 PARTIAL

"Osteoclasts are present in normal or elevated numbers in individuals affected by autosomal recessive osteopetrosis, suggesting that the defect is not in osteoclast differentiation, but in a gene involved in the functional capacity of mature osteoclasts"

Establishes that osteoclasts differentiate normally but are non-functional.

Progressive Skeletal Sclerosis

Failure of osteoclast-mediated bone resorption leads to progressive accumulation of unremodeled bone, obliterating the medullary cavity and narrowing cranial nerve foramina.

Bone Remodeling link

Downstream

Bone Marrow Failure from Medullary Obliteration Progressive accumulation of unresorbed bone obliterates marrow space.

Cranial Nerve Compression from Skull Thickening Progressive skull sclerosis narrows cranial nerve foramina.

Show evidence (1 reference)

PMID:10888887 PARTIAL

"mutations in TCIRG1 are a frequent cause of autosomal recessive osteopetrosis in humans"

TCIRG1 deficiency causes progressive skeletal sclerosis from failed bone resorption.

Bone Marrow Failure from Medullary Obliteration

Progressive accumulation of unremodeled bone obliterates the medullary cavity, causing loss of hematopoietic marrow space with resultant pancytopenia. Compensatory extramedullary hematopoiesis in liver and spleen causes hepatosplenomegaly.

Hematopoiesis link

Show evidence (1 reference)

PMID:10888887 SUPPORT

"Infantile malignant autosomal recessive osteopetrosis (MIM 259700) is a severe bone disease with a fatal outcome, generally within the first decade of life"

The fatal outcome is primarily due to bone marrow failure from medullary obliteration.

Cranial Nerve Compression from Skull Thickening

Progressive skull thickening narrows cranial nerve foramina, causing optic nerve compression (blindness), facial nerve palsy, and sensorineural hearing loss.

Cranium link

⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

●

Phenotypes

Blood 2

Anemia Anemia (HP:0001903)

Show evidence (2 references)

PMID:34545712 SUPPORT Human Clinical

"five Chinese children who presented with anemia, thrombocytopenia, hepatosplenomegaly, repeated infections, and increased bone density"

The autosomal recessive osteopetrosis cohort, including 3 TCIRG1 cases, explicitly presented with anemia.

PMID:40462430 SUPPORT Human Clinical

"Clinical manifestations included systemic osteosclerosis (14 cases, 100%), anemia (12 cases, 86%)"

A pediatric osteopetrosis cohort found anemia in most affected children; all TCIRG1 cases had malignant phenotypes.

Thrombocytopenia Thrombocytopenia (HP:0001873)

Show evidence (2 references)

PMID:34545712 SUPPORT Human Clinical

"five Chinese children who presented with anemia, thrombocytopenia, hepatosplenomegaly, repeated infections, and increased bone density"

The autosomal recessive osteopetrosis cohort, including 3 TCIRG1 cases, explicitly presented with thrombocytopenia.

PMID:40462430 SUPPORT Human Clinical

"Clinical manifestations included systemic osteosclerosis (14 cases, 100%), anemia (12 cases, 86%), infections (10 cases, 71%), thrombocytopenia (9 cases, 64%)"

A pediatric osteopetrosis cohort found thrombocytopenia in most children with malignant disease enrichment among TCIRG1 cases.

Cardiovascular 1

Hepatosplenomegaly Hepatosplenomegaly (HP:0001433)

Show evidence (2 references)

PMID:34545712 SUPPORT Human Clinical

"five Chinese children who presented with anemia, thrombocytopenia, hepatosplenomegaly, repeated infections, and increased bone density"

Hepatosplenomegaly was part of the presenting phenotype in an autosomal recessive osteopetrosis cohort that included 3 TCIRG1 cases.

PMID:18946580 SUPPORT Human Clinical

"The patient was a 5-year-old girl with macrocephaly, facial dysmorphism, blindness, mental retardation, hepatosplenomegaly, pancytopenia, and osteosclerotic changes in the skull and limb."

A TCIRG1-associated infantile malignant osteopetrosis case directly documented hepatosplenomegaly.

Ear 1

Hearing impairment Hearing impairment (HP:0000365)

Show evidence (1 reference)

PMID:30898950 SUPPORT Human Clinical

"Neurological manifestations can also occur due to narrowing of osseous foramina resulting in visual impairment, hearing loss, facial palsy and hydrocephalus."

The malignant infantile phenotype includes hearing loss from cranial foraminal narrowing.

Eye 1

Visual impairment Visual impairment (HP:0000505)

Show evidence (2 references)

PMID:30898950 SUPPORT Human Clinical

"Neurological manifestations can also occur due to narrowing of osseous foramina resulting in visual impairment, hearing loss, facial palsy and hydrocephalus."

Malignant infantile osteopetrosis causes visual impairment through cranial foraminal narrowing.

PMID:18946580 SUPPORT Human Clinical

"The patient was a 5-year-old girl with macrocephaly, facial dysmorphism, blindness, mental retardation, hepatosplenomegaly, pancytopenia, and osteosclerotic changes in the skull and limb."

A TCIRG1-associated case shows that visual involvement may be severe enough to cause blindness.

Head and Neck 1

Macrocephaly Macrocephaly (HP:0000256)

Show evidence (2 references)

PMID:18946580 SUPPORT Human Clinical

"The patient was a 5-year-old girl with macrocephaly, facial dysmorphism, blindness, mental retardation, hepatosplenomegaly, pancytopenia, and osteosclerotic changes in the skull and limb."

A TCIRG1-associated infantile malignant osteopetrosis case directly documented macrocephaly.

PMID:34519872 SUPPORT Human Clinical

"At 6 months, the infant had macrocephaly and frontal bossing with a bulging fontanelle."

Hydrocephalus-associated infantile osteopetrosis can present with macrocephaly and frontal bossing.

Immune 1

Recurrent infections Recurrent infections (HP:0002719)

Show evidence (2 references)

PMID:34545712 SUPPORT Human Clinical

"five Chinese children who presented with anemia, thrombocytopenia, hepatosplenomegaly, repeated infections, and increased bone density"

Repeated infections were part of the presenting phenotype in an autosomal recessive osteopetrosis cohort that included 3 TCIRG1 cases.

PMID:30898950 SUPPORT Human Clinical

"In addition, growth retardation and recurrent infections requiring long-term antibiotic use are common."

A TCIRG1-related malignant infantile osteopetrosis report highlights recurrent infections as a common clinical problem.

Metabolism 1

Hypocalcemia Hypocalcemia (HP:0002901)

Show evidence (1 reference)

PMID:34519872 SUPPORT Human Clinical

"Autosomal recessive osteopetrosis has a variable presentation, most commonly including failure to thrive, hypocalcemia, seizures, hepatosplenomegaly, hydrocephalus, vision or hearing loss, and cytopenias."

Hypocalcemia is identified as a common manifestation of autosomal recessive osteopetrosis.

Musculoskeletal 1

Increased bone mineral density Increased bone mineral density (HP:0011001)

Show evidence (2 references)

PMID:34545712 SUPPORT Human Clinical

"Osteopetrosis is characterized by increased bone density and bone marrow cavity stenosis"

An autosomal recessive osteopetrosis cohort that included 3 TCIRG1 cases identified increased bone density with marrow cavity stenosis as a core manifestation.

PMID:40462430 SUPPORT Human Clinical

"Clinical manifestations included systemic osteosclerosis (14 cases, 100%)"

A pediatric osteopetrosis cohort found systemic osteosclerosis in all affected children; all TCIRG1 cases had malignant phenotypes.

Nervous System 3

Hydrocephalus Hydrocephalus (HP:0000238)

Show evidence (2 references)

PMID:34519872 SUPPORT Human Clinical

A clinical report on malignant infantile osteopetrosis identifies hydrocephalus among the common presenting manifestations.

PMID:30898950 SUPPORT Human Clinical

"Neurological manifestations can also occur due to narrowing of osseous foramina resulting in visual impairment, hearing loss, facial palsy and hydrocephalus."

Independent clinical evidence links malignant infantile osteopetrosis to hydrocephalus from cranial narrowing.

Seizure Seizure (HP:0001250)

Show evidence (1 reference)

PMID:34519872 SUPPORT Human Clinical

Seizures are listed among the common presenting manifestations of autosomal recessive osteopetrosis.

Neurodevelopmental delay Neurodevelopmental delay (HP:0012758)

Show evidence (1 reference)

PMID:40462430 SUPPORT Human Clinical

"Clinical manifestations included systemic osteosclerosis (14 cases, 100%), anemia (12 cases, 86%), infections (10 cases, 71%), thrombocytopenia (9 cases, 64%), hepatosplenomegaly (8 cases, 57%), and developmental delay (5 cases, 36%)."

A pediatric osteopetrosis cohort documented developmental delay in a substantial subset of children; all TCIRG1 cases in the cohort had malignant phenotypes.

Growth 1

Failure to thrive Failure to thrive (HP:0001508)

Show evidence (1 reference)

PMID:34519872 SUPPORT Human Clinical

Failure to thrive is listed among the common presenting manifestations of autosomal recessive osteopetrosis.

🧬

Genetic Associations

TCIRG1 Mutations (Causative)

Show evidence (1 reference)

PMID:10888887 SUPPORT

"TCIRG1, encoding the osteoclast-specific 116-kD subunit of the vacuolar proton pump, is mutated in five of nine patients with a diagnosis of infantile malignant osteopetrosis"

TCIRG1 mutations found in 5/9 (56%) of infantile ARO patients.

TNFSF11 (Pathogenic Variants)

Show evidence (1 reference)

CGGV:assertion_90e426a0-23df-43d0-951c-ab6d7eb41158-2024-12-02T170000.000Z SUPPORT Other

ClinGen classifies the TNFSF11-autosomal recessive osteopetrosis 2 gene-disease relationship as definitive with autosomal recessive inheritance.

💊

Treatments

Hematopoietic Stem Cell Transplantation

Action: organ transplantation MAXO:0010039

The only curative treatment for infantile malignant osteopetrosis. Donor-derived osteoclasts replace defective host osteoclasts and restore bone resorption capacity. Early transplantation before irreversible complications is critical.

Genetic Counseling

Action: genetic counseling MAXO:0000079

Genetic counseling for affected families given autosomal recessive inheritance. Carrier testing and prenatal diagnosis available.

{ }

Source YAML

click to show

name: Autosomal Recessive Osteopetrosis Type 2
creation_date: '2026-02-13T00:31:42Z'
updated_date: '2026-05-08T16:21:17Z'
category: Mendelian
description: >
  Autosomal recessive osteopetrosis type 2 (ARO2) is a severe sclerosing bone
  disease caused by biallelic loss-of-function mutations in TCIRG1, encoding the
  osteoclast-specific a3 subunit of the vacuolar H+-ATPase. TCIRG1 mutations are
  the most frequent cause of infantile malignant osteopetrosis, accounting for over
  50% of ARO cases. Osteoclasts are present in normal or elevated numbers but are
  non-functional due to inability to acidify the resorption lacuna. The disease is
  characterized by dense but brittle bones, bone marrow failure, cranial nerve
  compression, and hepatosplenomegaly. Without hematopoietic stem cell
  transplantation, the disease is fatal within the first decade of life.
disease_term:
  preferred_term: autosomal recessive osteopetrosis 2
  term:
    id: MONDO:0009816
    label: autosomal recessive osteopetrosis 2
parents:
- Sclerosing Bone Dysplasias
inheritance:
- name: Autosomal Recessive
  description: >
    Autosomal recessive inheritance. Biallelic (homozygous or compound
    heterozygous) TCIRG1 mutations.
  evidence:
  - reference: PMID:10888887
    reference_title: "Defects in TCIRG1 subunit of the vacuolar proton pump are responsible for a subset of human autosomal recessive osteopetrosis."
    supports: PARTIAL
    snippet: "TCIRG1, encoding the osteoclast-specific 116-kD subunit of the vacuolar proton pump, is mutated in five of nine patients with a diagnosis of infantile malignant osteopetrosis"
    explanation: "TCIRG1 mutations identified as a frequent cause of autosomal recessive osteopetrosis."
prevalence:
- population: Global live births
  percentage: 1 in 250,000
  notes: >-
    Autosomal recessive osteopetrosis is estimated to occur in about 1 in
    250,000 births overall. Because biallelic TCIRG1 variants account for more
    than half of autosomal recessive osteopetrosis cases, autosomal recessive
    osteopetrosis type 2 is the most common molecular subtype within this
    incidence estimate.
  evidence:
  - reference: PMID:19232111
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "autosomal recessive osteopetrosis (ARO) has an incidence of 1 in 250,000 births"
    explanation: >-
      This review gives the standard incidence estimate for autosomal recessive
      osteopetrosis.
  - reference: PMID:22231430
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Biallelic mutations in the TCIRG1 gene, encoding for the a3 subunit of this pump, are responsible for more than one half of ARO patients."
    explanation: >-
      This study shows that TCIRG1-related disease represents the majority of
      autosomal recessive osteopetrosis cases, contextualizing prevalence for
      this subtype-specific file.
pathophysiology:
- name: Vacuolar Proton Pump Deficiency in Osteoclasts
  description: >
    TCIRG1 encodes the a3 subunit of the vacuolar H+-ATPase (V-ATPase),
    which is specifically expressed in osteoclasts and essential for proton
    secretion into the resorption lacuna. Loss-of-function mutations abolish
    osteoclast acidification capacity, preventing dissolution of hydroxyapatite
    mineral in bone matrix. Osteoclasts differentiate normally and are present
    in normal or elevated numbers but cannot resorb bone.
  biological_processes:
  - preferred_term: Bone Resorption
    term:
      id: GO:0045453
      label: bone resorption
  cell_types:
  - preferred_term: Osteoclast
    term:
      id: CL:0000092
      label: osteoclast
  evidence:
  - reference: PMID:10888887
    reference_title: "Defects in TCIRG1 subunit of the vacuolar proton pump are responsible for a subset of human autosomal recessive osteopetrosis."
    supports: PARTIAL
    snippet: "TCIRG1, encoding the osteoclast-specific 116-kD subunit of the vacuolar proton pump, is mutated in five of nine patients"
    explanation: "Identifies TCIRG1 and the vacuolar proton pump as the pathogenic target."
  - reference: PMID:10888887
    reference_title: "Defects in TCIRG1 subunit of the vacuolar proton pump are responsible for a subset of human autosomal recessive osteopetrosis."
    supports: PARTIAL
    snippet: "Osteoclasts are present in normal or elevated numbers in individuals affected by autosomal recessive osteopetrosis, suggesting that the defect is not in osteoclast differentiation, but in a gene involved in the functional capacity of mature osteoclasts"
    explanation: "Establishes that osteoclasts differentiate normally but are non-functional."
  downstream:
  - target: Progressive Skeletal Sclerosis
    description: >-
      Loss of osteoclast proton-pump function prevents normal bone resorption
      and drives skeletal sclerosis.
- name: Progressive Skeletal Sclerosis
  description: >
    Failure of osteoclast-mediated bone resorption leads to progressive
    accumulation of unremodeled bone, obliterating the medullary cavity
    and narrowing cranial nerve foramina.
  biological_processes:
  - preferred_term: Bone Remodeling
    term:
      id: GO:0046849
      label: bone remodeling
  evidence:
  - reference: PMID:10888887
    reference_title: "Defects in TCIRG1 subunit of the vacuolar proton pump are responsible for a subset of human autosomal recessive osteopetrosis."
    supports: PARTIAL
    snippet: "mutations in TCIRG1 are a frequent cause of autosomal recessive osteopetrosis in humans"
    explanation: "TCIRG1 deficiency causes progressive skeletal sclerosis from failed bone resorption."
  downstream:
  - target: Bone Marrow Failure from Medullary Obliteration
    description: >-
      Progressive accumulation of unresorbed bone obliterates marrow space.
  - target: Cranial Nerve Compression from Skull Thickening
    description: >-
      Progressive skull sclerosis narrows cranial nerve foramina.
- name: Bone Marrow Failure from Medullary Obliteration
  description: >
    Progressive accumulation of unremodeled bone obliterates the medullary
    cavity, causing loss of hematopoietic marrow space with resultant
    pancytopenia. Compensatory extramedullary hematopoiesis in liver and
    spleen causes hepatosplenomegaly.
  biological_processes:
  - preferred_term: Hematopoiesis
    term:
      id: GO:0030097
      label: hemopoiesis
  evidence:
  - reference: PMID:10888887
    reference_title: "Defects in TCIRG1 subunit of the vacuolar proton pump are responsible for a subset of human autosomal recessive osteopetrosis."
    supports: SUPPORT
    snippet: "Infantile malignant autosomal recessive osteopetrosis (MIM 259700) is a severe bone disease with a fatal outcome, generally within the first decade of life"
    explanation: "The fatal outcome is primarily due to bone marrow failure from medullary obliteration."
- name: Cranial Nerve Compression from Skull Thickening
  description: >
    Progressive skull thickening narrows cranial nerve foramina, causing
    optic nerve compression (blindness), facial nerve palsy, and
    sensorineural hearing loss.
  locations:
  - preferred_term: Cranium
    term:
      id: UBERON:0003128
      label: cranium
phenotypes:
- name: Increased bone mineral density
  description: >
    Generalized osteosclerosis with narrowing or obliteration of marrow
    cavities is the defining skeletal manifestation of TCIRG1-related
    autosomal recessive osteopetrosis.
  phenotype_term:
    preferred_term: Increased bone mineral density
    term:
      id: HP:0011001
      label: Increased bone mineral density
  evidence:
  - reference: PMID:34545712
    reference_title: "Clinical and molecular characterization of five Chinese patients with autosomal recessive osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Osteopetrosis is characterized by increased bone density and bone marrow cavity stenosis"
    explanation: "An autosomal recessive osteopetrosis cohort that included 3 TCIRG1 cases identified increased bone density with marrow cavity stenosis as a core manifestation."
  - reference: PMID:40462430
    reference_title: "[Clinical and genetic characteristics of osteopetrosis in children]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical manifestations included systemic osteosclerosis (14 cases, 100%)"
    explanation: "A pediatric osteopetrosis cohort found systemic osteosclerosis in all affected children; all TCIRG1 cases had malignant phenotypes."
- name: Anemia
  description: >
    Progressive medullary cavity compromise causes clinically important
    anemia early in the malignant infantile phenotype.
  phenotype_term:
    preferred_term: Anemia
    term:
      id: HP:0001903
      label: Anemia
  evidence:
  - reference: PMID:34545712
    reference_title: "Clinical and molecular characterization of five Chinese patients with autosomal recessive osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "five Chinese children who presented with anemia, thrombocytopenia, hepatosplenomegaly, repeated infections, and increased bone density"
    explanation: "The autosomal recessive osteopetrosis cohort, including 3 TCIRG1 cases, explicitly presented with anemia."
  - reference: PMID:40462430
    reference_title: "[Clinical and genetic characteristics of osteopetrosis in children]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical manifestations included systemic osteosclerosis (14 cases, 100%), anemia (12 cases, 86%)"
    explanation: "A pediatric osteopetrosis cohort found anemia in most affected children; all TCIRG1 cases had malignant phenotypes."
- name: Thrombocytopenia
  description: >
    Bone marrow failure commonly includes thrombocytopenia, contributing
    to bleeding risk in severe infantile disease.
  phenotype_term:
    preferred_term: Thrombocytopenia
    term:
      id: HP:0001873
      label: Thrombocytopenia
  evidence:
  - reference: PMID:34545712
    reference_title: "Clinical and molecular characterization of five Chinese patients with autosomal recessive osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "five Chinese children who presented with anemia, thrombocytopenia, hepatosplenomegaly, repeated infections, and increased bone density"
    explanation: "The autosomal recessive osteopetrosis cohort, including 3 TCIRG1 cases, explicitly presented with thrombocytopenia."
  - reference: PMID:40462430
    reference_title: "[Clinical and genetic characteristics of osteopetrosis in children]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical manifestations included systemic osteosclerosis (14 cases, 100%), anemia (12 cases, 86%), infections (10 cases, 71%), thrombocytopenia (9 cases, 64%)"
    explanation: "A pediatric osteopetrosis cohort found thrombocytopenia in most children with malignant disease enrichment among TCIRG1 cases."
- name: Hepatosplenomegaly
  description: >
    Hepatosplenomegaly reflects compensatory extramedullary hematopoiesis
    in response to marrow failure.
  phenotype_term:
    preferred_term: Hepatosplenomegaly
    term:
      id: HP:0001433
      label: Hepatosplenomegaly
  evidence:
  - reference: PMID:34545712
    reference_title: "Clinical and molecular characterization of five Chinese patients with autosomal recessive osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "five Chinese children who presented with anemia, thrombocytopenia, hepatosplenomegaly, repeated infections, and increased bone density"
    explanation: "Hepatosplenomegaly was part of the presenting phenotype in an autosomal recessive osteopetrosis cohort that included 3 TCIRG1 cases."
  - reference: PMID:18946580
    reference_title: "Rare gross deletion in T-cell immune regulator-1 gene in Iranian family with infantile malignant osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The patient was a 5-year-old girl with macrocephaly, facial dysmorphism, blindness, mental retardation, hepatosplenomegaly, pancytopenia, and osteosclerotic changes in the skull and limb."
    explanation: "A TCIRG1-associated infantile malignant osteopetrosis case directly documented hepatosplenomegaly."
- name: Recurrent infections
  description: >
    Recurrent infections are common in severe disease and likely reflect
    marrow failure with impaired hematopoiesis.
  phenotype_term:
    preferred_term: Recurrent infections
    term:
      id: HP:0002719
      label: Recurrent infections
  evidence:
  - reference: PMID:34545712
    reference_title: "Clinical and molecular characterization of five Chinese patients with autosomal recessive osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "five Chinese children who presented with anemia, thrombocytopenia, hepatosplenomegaly, repeated infections, and increased bone density"
    explanation: "Repeated infections were part of the presenting phenotype in an autosomal recessive osteopetrosis cohort that included 3 TCIRG1 cases."
  - reference: PMID:30898950
    reference_title: "Osteomyelitis of the mandible secondary to malignant infantile osteopetrosis in an adult."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In addition, growth retardation and recurrent infections requiring long-term antibiotic use are common."
    explanation: "A TCIRG1-related malignant infantile osteopetrosis report highlights recurrent infections as a common clinical problem."
- name: Visual impairment
  description: >
    Skull-base overgrowth and narrowing of osseous foramina can compress
    the optic apparatus, causing visual impairment that may progress to
    blindness.
  phenotype_term:
    preferred_term: Visual impairment
    term:
      id: HP:0000505
      label: Visual impairment
  evidence:
  - reference: PMID:30898950
    reference_title: "Osteomyelitis of the mandible secondary to malignant infantile osteopetrosis in an adult."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Neurological manifestations can also occur due to narrowing of osseous foramina resulting in visual impairment, hearing loss, facial palsy and hydrocephalus."
    explanation: "Malignant infantile osteopetrosis causes visual impairment through cranial foraminal narrowing."
  - reference: PMID:18946580
    reference_title: "Rare gross deletion in T-cell immune regulator-1 gene in Iranian family with infantile malignant osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The patient was a 5-year-old girl with macrocephaly, facial dysmorphism, blindness, mental retardation, hepatosplenomegaly, pancytopenia, and osteosclerotic changes in the skull and limb."
    explanation: "A TCIRG1-associated case shows that visual involvement may be severe enough to cause blindness."
- name: Hearing impairment
  description: >
    Bony narrowing of cranial foramina and temporal bone involvement can
    cause clinically significant hearing loss.
  phenotype_term:
    preferred_term: Hearing impairment
    term:
      id: HP:0000365
      label: Hearing impairment
  evidence:
  - reference: PMID:30898950
    reference_title: "Osteomyelitis of the mandible secondary to malignant infantile osteopetrosis in an adult."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Neurological manifestations can also occur due to narrowing of osseous foramina resulting in visual impairment, hearing loss, facial palsy and hydrocephalus."
    explanation: "The malignant infantile phenotype includes hearing loss from cranial foraminal narrowing."
- name: Hydrocephalus
  description: >
    Hydrocephalus is a recognized cranial complication of severe
    autosomal recessive osteopetrosis and may be an early presenting
    feature.
  phenotype_term:
    preferred_term: Hydrocephalus
    term:
      id: HP:0000238
      label: Hydrocephalus
  evidence:
  - reference: PMID:34519872
    reference_title: "Neonatal hydrocephalus: an atypical presentation of malignant infantile osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal recessive osteopetrosis has a variable presentation, most commonly including failure to thrive, hypocalcemia, seizures, hepatosplenomegaly, hydrocephalus, vision or hearing loss, and cytopenias."
    explanation: "A clinical report on malignant infantile osteopetrosis identifies hydrocephalus among the common presenting manifestations."
  - reference: PMID:30898950
    reference_title: "Osteomyelitis of the mandible secondary to malignant infantile osteopetrosis in an adult."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Neurological manifestations can also occur due to narrowing of osseous foramina resulting in visual impairment, hearing loss, facial palsy and hydrocephalus."
    explanation: "Independent clinical evidence links malignant infantile osteopetrosis to hydrocephalus from cranial narrowing."
- name: Macrocephaly
  description: >
    Progressive cranial overgrowth can produce macrocephaly, often with
    frontal bossing in infants.
  phenotype_term:
    preferred_term: Macrocephaly
    term:
      id: HP:0000256
      label: Macrocephaly
  evidence:
  - reference: PMID:18946580
    reference_title: "Rare gross deletion in T-cell immune regulator-1 gene in Iranian family with infantile malignant osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The patient was a 5-year-old girl with macrocephaly, facial dysmorphism, blindness, mental retardation, hepatosplenomegaly, pancytopenia, and osteosclerotic changes in the skull and limb."
    explanation: "A TCIRG1-associated infantile malignant osteopetrosis case directly documented macrocephaly."
  - reference: PMID:34519872
    reference_title: "Neonatal hydrocephalus: an atypical presentation of malignant infantile osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "At 6 months, the infant had macrocephaly and frontal bossing with a bulging fontanelle."
    explanation: "Hydrocephalus-associated infantile osteopetrosis can present with macrocephaly and frontal bossing."
- name: Failure to thrive
  description: >
    Poor growth and nutritional failure are part of the common early
    presentation of severe autosomal recessive osteopetrosis.
  phenotype_term:
    preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
  evidence:
  - reference: PMID:34519872
    reference_title: "Neonatal hydrocephalus: an atypical presentation of malignant infantile osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal recessive osteopetrosis has a variable presentation, most commonly including failure to thrive, hypocalcemia, seizures, hepatosplenomegaly, hydrocephalus, vision or hearing loss, and cytopenias."
    explanation: "Failure to thrive is listed among the common presenting manifestations of autosomal recessive osteopetrosis."
- name: Hypocalcemia
  description: >
    Impaired bone resorption is commonly accompanied by hypocalcemia in
    severe infantile presentations.
  phenotype_term:
    preferred_term: Hypocalcemia
    term:
      id: HP:0002901
      label: Hypocalcemia
  evidence:
  - reference: PMID:34519872
    reference_title: "Neonatal hydrocephalus: an atypical presentation of malignant infantile osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal recessive osteopetrosis has a variable presentation, most commonly including failure to thrive, hypocalcemia, seizures, hepatosplenomegaly, hydrocephalus, vision or hearing loss, and cytopenias."
    explanation: "Hypocalcemia is identified as a common manifestation of autosomal recessive osteopetrosis."
- name: Seizure
  description: >
    Seizures can occur in the malignant infantile phenotype, often in the
    setting of metabolic derangements such as hypocalcemia.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:34519872
    reference_title: "Neonatal hydrocephalus: an atypical presentation of malignant infantile osteopetrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal recessive osteopetrosis has a variable presentation, most commonly including failure to thrive, hypocalcemia, seizures, hepatosplenomegaly, hydrocephalus, vision or hearing loss, and cytopenias."
    explanation: "Seizures are listed among the common presenting manifestations of autosomal recessive osteopetrosis."
- name: Neurodevelopmental delay
  description: >
    Severe disease may be accompanied by delayed neurodevelopment,
    particularly when early neurologic complications occur.
  phenotype_term:
    preferred_term: Neurodevelopmental delay
    term:
      id: HP:0012758
      label: Neurodevelopmental delay
  evidence:
  - reference: PMID:40462430
    reference_title: "[Clinical and genetic characteristics of osteopetrosis in children]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical manifestations included systemic osteosclerosis (14 cases, 100%), anemia (12 cases, 86%), infections (10 cases, 71%), thrombocytopenia (9 cases, 64%), hepatosplenomegaly (8 cases, 57%), and developmental delay (5 cases, 36%)."
    explanation: "A pediatric osteopetrosis cohort documented developmental delay in a substantial subset of children; all TCIRG1 cases in the cohort had malignant phenotypes."
genetic:
- name: TCIRG1 Mutations
  association: Causative
  notes: >
    Homozygous or compound heterozygous loss-of-function mutations in
    TCIRG1 on chromosome 11q13.2, encoding the osteoclast-specific a3
    subunit of the vacuolar H+-ATPase. TCIRG1 mutations account for
    over 50% of all ARO cases.
  evidence:
  - reference: PMID:10888887
    reference_title: "Defects in TCIRG1 subunit of the vacuolar proton pump are responsible for a subset of human autosomal recessive osteopetrosis."
    supports: SUPPORT
    snippet: "TCIRG1, encoding the osteoclast-specific 116-kD subunit of the vacuolar proton pump, is mutated in five of nine patients with a diagnosis of infantile malignant osteopetrosis"
    explanation: "TCIRG1 mutations found in 5/9 (56%) of infantile ARO patients."
- name: TNFSF11
  gene_term:
    preferred_term: TNFSF11
    term:
      id: hgnc:11926
      label: TNFSF11
  association: Pathogenic Variants
  evidence:
  - reference: CGGV:assertion_90e426a0-23df-43d0-951c-ab6d7eb41158-2024-12-02T170000.000Z
    reference_title: "TNFSF11 / autosomal recessive osteopetrosis 2 (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "TNFSF11 | HGNC:11926 | autosomal recessive osteopetrosis 2 | MONDO:0009816 | AR | Definitive"
    explanation: ClinGen classifies the TNFSF11-autosomal recessive osteopetrosis 2 gene-disease relationship as definitive with autosomal recessive inheritance.
treatments:
- name: Hematopoietic Stem Cell Transplantation
  description: >
    The only curative treatment for infantile malignant osteopetrosis.
    Donor-derived osteoclasts replace defective host osteoclasts and
    restore bone resorption capacity. Early transplantation before
    irreversible complications is critical.
  treatment_term:
    preferred_term: organ transplantation
    term:
      id: MAXO:0010039
      label: organ transplantation
- name: Genetic Counseling
  description: >
    Genetic counseling for affected families given autosomal recessive
    inheritance. Carrier testing and prenatal diagnosis available.
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: MAXO:0000079
      label: genetic counseling
references:
- reference: DOI:10.1093/stcltm/szab019
  title: Alterations in Hematopoietic and Mesenchymal Stromal Cell Components of the Osteopetrotic Bone Marrow Niche
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: Osteopetrosis is a rare inherited disease characterized by impaired osteoclast activity causing defective bone resorption and bone marrow aplasia.
    supporting_text: Osteopetrosis is a rare inherited disease characterized by impaired osteoclast activity causing defective bone resorption and bone marrow aplasia.
    evidence:
    - reference: DOI:10.1093/stcltm/szab019
      reference_title: Alterations in Hematopoietic and Mesenchymal Stromal Cell Components of the Osteopetrotic Bone Marrow Niche
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Osteopetrosis is a rare inherited disease characterized by impaired osteoclast activity causing defective bone resorption and bone marrow aplasia.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.
- reference: DOI:10.1182/blood-2015-01-625541
  title: Hematopoietic stem cell transplantation for infantile osteopetrosis
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: Key PointsHematopoietic cell transplantation results in long-term survival.
    supporting_text: Key PointsHematopoietic cell transplantation results in long-term survival.
    evidence:
    - reference: DOI:10.1182/blood-2015-01-625541
      reference_title: Hematopoietic stem cell transplantation for infantile osteopetrosis
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Key PointsHematopoietic cell transplantation results in long-term survival.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.
- reference: DOI:10.1186/s13023-021-01955-6
  title: 'Haploidentical haematopoietic stem cell transplantation for malignant infantile osteopetrosis and intermediate osteopetrosis: a retrospective analysis of a single centre'
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: To evaluate the clinical efficacy of haploidentical haematopoietic stem cell transplantation (haplo-HSCT) for the treatment of malignant infantile osteopetrosis (MIOP) and intermediate osteopetrosis.
    supporting_text: To evaluate the clinical efficacy of haploidentical haematopoietic stem cell transplantation (haplo-HSCT) for the treatment of malignant infantile osteopetrosis (MIOP) and intermediate osteopetrosis.
    evidence:
    - reference: DOI:10.1186/s13023-021-01955-6
      reference_title: 'Haploidentical haematopoietic stem cell transplantation for malignant infantile osteopetrosis and intermediate osteopetrosis: a retrospective analysis of a single centre'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: To evaluate the clinical efficacy of haploidentical haematopoietic stem cell transplantation (haplo-HSCT) for the treatment of malignant infantile osteopetrosis (MIOP) and intermediate osteopetrosis.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.
- reference: DOI:10.1242/dmm.048940
  title: 'Autosomal recessive osteopetrosis: mechanisms and treatments'
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: Autosomal recessive osteopetrosis (ARO) is a severe inherited bone disease characterized by defective osteoclast resorption or differentiation.
    supporting_text: Autosomal recessive osteopetrosis (ARO) is a severe inherited bone disease characterized by defective osteoclast resorption or differentiation.
    evidence:
    - reference: DOI:10.1242/dmm.048940
      reference_title: 'Autosomal recessive osteopetrosis: mechanisms and treatments'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Autosomal recessive osteopetrosis (ARO) is a severe inherited bone disease characterized by defective osteoclast resorption or differentiation.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.
- reference: DOI:10.18699/vjgb-23-46
  title: Clinical, genetic aspects and molecular pathogenesis of osteopetrosis
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: Osteopetrosis (“marble bone”, ICD-10-78.2) includes a group of hereditary bone disorders distinguished by clinical variability and genetic heterogeneity.
    supporting_text: Osteopetrosis (“marble bone”, ICD-10-78.2) includes a group of hereditary bone disorders distinguished by clinical variability and genetic heterogeneity.
    evidence:
    - reference: DOI:10.18699/vjgb-23-46
      reference_title: Clinical, genetic aspects and molecular pathogenesis of osteopetrosis
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Osteopetrosis (“marble bone”, ICD-10-78.2) includes a group of hereditary bone disorders distinguished by clinical variability and genetic heterogeneity.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.
- reference: DOI:10.2106/jbjs.19.00558
  title: TCIRG1 Transgenic Rescue of Osteoclast Function Using Induced Pluripotent Stem Cells Derived from Patients with Infantile Malignant Autosomal Recessive Osteopetrosis
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: Osteoclasts are hematopoietic stem cell-derived multinucleated cells necessary for bone remodeling and resorption.
    supporting_text: Osteoclasts are hematopoietic stem cell-derived multinucleated cells necessary for bone remodeling and resorption.
    evidence:
    - reference: DOI:10.2106/jbjs.19.00558
      reference_title: TCIRG1 Transgenic Rescue of Osteoclast Function Using Induced Pluripotent Stem Cells Derived from Patients with Infantile Malignant Autosomal Recessive Osteopetrosis
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Osteoclasts are hematopoietic stem cell-derived multinucleated cells necessary for bone remodeling and resorption.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.
- reference: DOI:10.3324/haematol.2019.238261
  title: Expanded circulating hematopoietic stem/progenitor cells as novel cell source for the treatment of TCIRG1 osteopetrosis
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: Allogeneic hematopoietic stem cell transplantation is the treatment of choice for autosomal recessive osteopetrosis caused by defects in the TCIRG1 gene.
    supporting_text: Allogeneic hematopoietic stem cell transplantation is the treatment of choice for autosomal recessive osteopetrosis caused by defects in the TCIRG1 gene.
    evidence:
    - reference: DOI:10.3324/haematol.2019.238261
      reference_title: Expanded circulating hematopoietic stem/progenitor cells as novel cell source for the treatment of TCIRG1 osteopetrosis
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Allogeneic hematopoietic stem cell transplantation is the treatment of choice for autosomal recessive osteopetrosis caused by defects in the TCIRG1 gene.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.
- reference: DOI:10.3389/fendo.2024.1450349
  title: Correction of osteopetrosis in the neonate oc/oc murine model after lentiviral vector gene therapy and non-genotoxic conditioning
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: Autosomal recessive osteopetrosis (ARO) is a rare genetic disease, characterized by increased bone density due to defective osteoclast function.
    supporting_text: Autosomal recessive osteopetrosis (ARO) is a rare genetic disease, characterized by increased bone density due to defective osteoclast function.
    evidence:
    - reference: DOI:10.3389/fendo.2024.1450349
      reference_title: Correction of osteopetrosis in the neonate oc/oc murine model after lentiviral vector gene therapy and non-genotoxic conditioning
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Autosomal recessive osteopetrosis (ARO) is a rare genetic disease, characterized by increased bone density due to defective osteoclast function.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.
- reference: DOI:10.3389/fped.2023.1096770
  title: 'Case report: Gene mutations and clinical characteristics of four patients with osteopetrosis'
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: 'Case report: Gene mutations and clinical characteristics of four patients with osteopetrosis'
    supporting_text: Osteopetrosis is characterized by increased bone density caused by decreased osteoclasts or dysfunction of their differentiation and absorption properties, usually caused by biallelic variants of the TCIRG1(OMIM:604592)and CLCN7(OMIM:602727) genes.
    evidence:
    - reference: DOI:10.3389/fped.2023.1096770
      reference_title: 'Case report: Gene mutations and clinical characteristics of four patients with osteopetrosis'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Osteopetrosis is characterized by increased bone density caused by decreased osteoclasts or dysfunction of their differentiation and absorption properties, usually caused by biallelic variants of the TCIRG1(OMIM:604592)and CLCN7(OMIM:602727) genes.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.
- reference: DOI:10.3389/fped.2023.978879
  title: A novel compound heterozygous mutation of the CLCN7 gene is associated with autosomal recessive osteopetrosis
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: Osteopetrosis is a genetic condition of the skeleton characterized by increased bone density caused by osteoclast formation and function defects.
    supporting_text: Osteopetrosis is a genetic condition of the skeleton characterized by increased bone density caused by osteoclast formation and function defects.
    evidence:
    - reference: DOI:10.3389/fped.2023.978879
      reference_title: A novel compound heterozygous mutation of the CLCN7 gene is associated with autosomal recessive osteopetrosis
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Osteopetrosis is a genetic condition of the skeleton characterized by increased bone density caused by osteoclast formation and function defects.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.
- reference: DOI:10.3390/genes14040900
  title: Outlining the Clinical Profile of TCIRG1 14 Variants including 5 Novels with Overview of ARO Phenotype and Ethnic Impact in 20 Egyptian Families
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: TCIRG1 gene mutations underlie osteopetrosis, a rare genetic disorder impacting osteoclast function with consequent brittle bones prone to fracture, in spite of being characterized by increased bone density.
    supporting_text: TCIRG1 gene mutations underlie osteopetrosis, a rare genetic disorder impacting osteoclast function with consequent brittle bones prone to fracture, in spite of being characterized by increased bone density.
    evidence:
    - reference: DOI:10.3390/genes14040900
      reference_title: Outlining the Clinical Profile of TCIRG1 14 Variants including 5 Novels with Overview of ARO Phenotype and Ethnic Impact in 20 Egyptian Families
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: TCIRG1 gene mutations underlie osteopetrosis, a rare genetic disorder impacting osteoclast function with consequent brittle bones prone to fracture, in spite of being characterized by increased bone density.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.
- reference: DOI:10.59213/tp.2025.249
  title: 'The clinical and genetic spectrum of infantile osteopetrosis: a single-center experience including a novel TCIRG1 mutation'
  found_in:
  - Autosomal_Recessive_Osteopetrosis-deep-research-falcon.md
  findings:
  - statement: Osteopetrosis (OP) is a rare, severe inherited disorder of bone metabolism caused by impaired osteoclast function.
    supporting_text: Osteopetrosis (OP) is a rare, severe inherited disorder of bone metabolism caused by impaired osteoclast function.
    evidence:
    - reference: DOI:10.59213/tp.2025.249
      reference_title: 'The clinical and genetic spectrum of infantile osteopetrosis: a single-center experience including a novel TCIRG1 mutation'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Osteopetrosis (OP) is a rare, severe inherited disorder of bone metabolism caused by impaired osteoclast function.
      explanation: Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

📚

References & Deep Research

References

DOI:10.1093/stcltm/szab019

Alterations in Hematopoietic and Mesenchymal Stromal Cell Components of the Osteopetrotic Bone Marrow Niche

1 finding

Osteopetrosis is a rare inherited disease characterized by impaired osteoclast activity causing defective bone resorption and bone marrow aplasia.

"Osteopetrosis is a rare inherited disease characterized by impaired osteoclast activity causing defective bone resorption and bone marrow aplasia."

Show evidence (1 reference)

DOI:10.1093/stcltm/szab019 SUPPORT Human Clinical

"Osteopetrosis is a rare inherited disease characterized by impaired osteoclast activity causing defective bone resorption and bone marrow aplasia."

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

DOI:10.1182/blood-2015-01-625541

Hematopoietic stem cell transplantation for infantile osteopetrosis

1 finding

Key PointsHematopoietic cell transplantation results in long-term survival.

"Key PointsHematopoietic cell transplantation results in long-term survival."

Show evidence (1 reference)

DOI:10.1182/blood-2015-01-625541 SUPPORT Human Clinical

"Key PointsHematopoietic cell transplantation results in long-term survival."

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

DOI:10.1186/s13023-021-01955-6

Haploidentical haematopoietic stem cell transplantation for malignant infantile osteopetrosis and intermediate osteopetrosis: a retrospective analysis of a single centre

1 finding

To evaluate the clinical efficacy of haploidentical haematopoietic stem cell transplantation (haplo-HSCT) for the treatment of malignant infantile osteopetrosis (MIOP) and intermediate osteopetrosis.

"To evaluate the clinical efficacy of haploidentical haematopoietic stem cell transplantation (haplo-HSCT) for the treatment of malignant infantile osteopetrosis (MIOP) and intermediate osteopetrosis."

Show evidence (1 reference)

DOI:10.1186/s13023-021-01955-6 SUPPORT Human Clinical

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

DOI:10.1242/dmm.048940

Autosomal recessive osteopetrosis: mechanisms and treatments

1 finding

Autosomal recessive osteopetrosis (ARO) is a severe inherited bone disease characterized by defective osteoclast resorption or differentiation.

"Autosomal recessive osteopetrosis (ARO) is a severe inherited bone disease characterized by defective osteoclast resorption or differentiation."

Show evidence (1 reference)

DOI:10.1242/dmm.048940 SUPPORT Human Clinical

"Autosomal recessive osteopetrosis (ARO) is a severe inherited bone disease characterized by defective osteoclast resorption or differentiation."

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

DOI:10.18699/vjgb-23-46

Clinical, genetic aspects and molecular pathogenesis of osteopetrosis

1 finding

Osteopetrosis (“marble bone”, ICD-10-78.2) includes a group of hereditary bone disorders distinguished by clinical variability and genetic heterogeneity.

"Osteopetrosis (“marble bone”, ICD-10-78.2) includes a group of hereditary bone disorders distinguished by clinical variability and genetic heterogeneity."

Show evidence (1 reference)

DOI:10.18699/vjgb-23-46 SUPPORT Human Clinical

"Osteopetrosis (“marble bone”, ICD-10-78.2) includes a group of hereditary bone disorders distinguished by clinical variability and genetic heterogeneity."

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

DOI:10.2106/jbjs.19.00558

TCIRG1 Transgenic Rescue of Osteoclast Function Using Induced Pluripotent Stem Cells Derived from Patients with Infantile Malignant Autosomal Recessive Osteopetrosis

1 finding

Osteoclasts are hematopoietic stem cell-derived multinucleated cells necessary for bone remodeling and resorption.

"Osteoclasts are hematopoietic stem cell-derived multinucleated cells necessary for bone remodeling and resorption."

Show evidence (1 reference)

DOI:10.2106/jbjs.19.00558 SUPPORT Human Clinical

"Osteoclasts are hematopoietic stem cell-derived multinucleated cells necessary for bone remodeling and resorption."

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

DOI:10.3324/haematol.2019.238261

Expanded circulating hematopoietic stem/progenitor cells as novel cell source for the treatment of TCIRG1 osteopetrosis

1 finding

Allogeneic hematopoietic stem cell transplantation is the treatment of choice for autosomal recessive osteopetrosis caused by defects in the TCIRG1 gene.

"Allogeneic hematopoietic stem cell transplantation is the treatment of choice for autosomal recessive osteopetrosis caused by defects in the TCIRG1 gene."

Show evidence (1 reference)

DOI:10.3324/haematol.2019.238261 SUPPORT Human Clinical

"Allogeneic hematopoietic stem cell transplantation is the treatment of choice for autosomal recessive osteopetrosis caused by defects in the TCIRG1 gene."

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

DOI:10.3389/fendo.2024.1450349

Correction of osteopetrosis in the neonate oc/oc murine model after lentiviral vector gene therapy and non-genotoxic conditioning

1 finding

Autosomal recessive osteopetrosis (ARO) is a rare genetic disease, characterized by increased bone density due to defective osteoclast function.

"Autosomal recessive osteopetrosis (ARO) is a rare genetic disease, characterized by increased bone density due to defective osteoclast function."

Show evidence (1 reference)

DOI:10.3389/fendo.2024.1450349 SUPPORT Model Organism

"Autosomal recessive osteopetrosis (ARO) is a rare genetic disease, characterized by increased bone density due to defective osteoclast function."

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

DOI:10.3389/fped.2023.1096770

Case report: Gene mutations and clinical characteristics of four patients with osteopetrosis

1 finding

Case report: Gene mutations and clinical characteristics of four patients with osteopetrosis

"Osteopetrosis is characterized by increased bone density caused by decreased osteoclasts or dysfunction of their differentiation and absorption properties, usually caused by biallelic variants of the TCIRG1(OMIM:604592)and CLCN7(OMIM:602727) genes."

Show evidence (1 reference)

DOI:10.3389/fped.2023.1096770 SUPPORT Human Clinical

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

DOI:10.3389/fped.2023.978879

A novel compound heterozygous mutation of the CLCN7 gene is associated with autosomal recessive osteopetrosis

1 finding

Osteopetrosis is a genetic condition of the skeleton characterized by increased bone density caused by osteoclast formation and function defects.

"Osteopetrosis is a genetic condition of the skeleton characterized by increased bone density caused by osteoclast formation and function defects."

Show evidence (1 reference)

DOI:10.3389/fped.2023.978879 SUPPORT Other

"Osteopetrosis is a genetic condition of the skeleton characterized by increased bone density caused by osteoclast formation and function defects."

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

DOI:10.3390/genes14040900

Outlining the Clinical Profile of TCIRG1 14 Variants including 5 Novels with Overview of ARO Phenotype and Ethnic Impact in 20 Egyptian Families

1 finding

TCIRG1 gene mutations underlie osteopetrosis, a rare genetic disorder impacting osteoclast function with consequent brittle bones prone to fracture, in spite of being characterized by increased bone density.

"TCIRG1 gene mutations underlie osteopetrosis, a rare genetic disorder impacting osteoclast function with consequent brittle bones prone to fracture, in spite of being characterized by increased bone density."

Show evidence (1 reference)

DOI:10.3390/genes14040900 SUPPORT Human Clinical

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

DOI:10.59213/tp.2025.249

The clinical and genetic spectrum of infantile osteopetrosis: a single-center experience including a novel TCIRG1 mutation

1 finding

Osteopetrosis (OP) is a rare, severe inherited disorder of bone metabolism caused by impaired osteoclast function.

"Osteopetrosis (OP) is a rare, severe inherited disorder of bone metabolism caused by impaired osteoclast function."

Show evidence (1 reference)

DOI:10.59213/tp.2025.249 SUPPORT Human Clinical

"Osteopetrosis (OP) is a rare, severe inherited disorder of bone metabolism caused by impaired osteoclast function."

Deep research cited this publication as relevant literature for Autosomal Recessive Osteopetrosis.

Deep Research

Falcon ▸

Disease Characteristics Research Template

Edison Scientific Literature 38 citations 2026-05-08T08:40:14.762560

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Characteristics Research Template

Target Disease

Disease Name: Autosomal Recessive Osteopetrosis Type 2
MONDO ID: (if available)
Category: Mendelian

Research Objectives

Please provide a comprehensive research report on Autosomal Recessive Osteopetrosis Type 2 covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.

For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.

1. Disease Information

Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed

What is the disease? Provide a concise overview.
What are the key identifiers? (OMIM, Orphanet, ICD-10/ICD-11, MeSH, Mondo)
What are the common synonyms and alternative names?
Is the information derived from individual patients (e.g., EHR) or aggregated disease-level resources?

2. Etiology

Disease Causal Factors: What are the primary causes? (genetic, environmental, infectious, mechanistic)
Risk Factors:

Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases
Genetic risk factors (causal variants, susceptibility loci, modifier genes)
Environmental risk factors (toxins, lifestyle, occupational exposures, age, sex, family history)
Protective Factors:

Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases
Genetic protective factors (protective variants, modifier alleles)
Environmental protective factors (diet, lifestyle, exposures that reduce risk)
Gene-Environment Interactions: How do genetic and environmental factors interact to influence disease?

Search first: CTD, PubMed, PheGenI, GxE databases

3. Phenotypes

Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC

For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities

For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype

4. Genetic/Molecular Information

Causal Genes: Gene mutations or chromosomal abnormalities responsible for disease (gene symbols, OMIM IDs)

Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene
Pathogenic Variants:
Affected genes (gene symbols, HGNC IDs) > Search first: OMIM, NCBI Gene, Ensembl, HGNC, UniProt, GeneCards
Variant classification (pathogenic, likely pathogenic, VUS per ACMG/AMP guidelines) > Search first: ClinVar, ClinGen, ACMG/AMP guidelines, VarSome
Variant type/class (missense, frameshift, nonsense, splice-site, structural)
Allele frequency in population databases > Search first: gnomAD, 1000 Genomes, ExAC, TOPMed, dbSNP
Somatic vs germline origin > Search first: COSMIC (somatic), ClinVar, ICGC, TCGA
Functional consequences (loss of function, gain of function, dominant negative)
Modifier Genes: Genes that modify disease severity or expression
Epigenetic Information: DNA methylation, histone modifications, chromatin changes affecting disease

Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
Chromosomal Abnormalities: Large-scale genetic changes (aneuploidy, translocations, inversions)

Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser

5. Environmental Information

Environmental Factors: Non-genetic contributing factors (toxins, radiation, pollution, occupational exposure)

Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases
Lifestyle Factors: Behavioral factors (smoking, diet, exercise, alcohol consumption)

Search first: CDC databases, WHO, PubMed, NHANES
Infectious Agents: If applicable, pathogens causing or triggering disease (bacteria, viruses, fungi, parasites)

Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON

6. Mechanism / Pathophysiology

Molecular Pathways: Specific signaling cascades or biochemical pathways involved (Wnt, MAPK, mTOR, PI3K-AKT, etc.)

Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc
Cellular Processes: Cell-level mechanisms (apoptosis, autophagy, cell cycle dysregulation, inflammation, etc.)

Search first: Gene Ontology (GO), Reactome, KEGG, PubMed
Protein Dysfunction: How protein structure or function is altered (misfolding, aggregation, loss of function, gain of function)

Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold
Metabolic Changes: Alterations in metabolic processes (energy metabolism, lipid metabolism, amino acid metabolism)

Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA
Immune System Involvement: Role of immune response (autoimmunity, immunodeficiency, chronic inflammation)

Search first: ImmPort, Immunome Database, IEDB, Gene Ontology
Tissue Damage Mechanisms: How tissues/ are injured (oxidative stress, ischemia, fibrosis, necrosis)

Search first: PubMed, Gene Ontology, Reactome
Biochemical Abnormalities: Specific molecular defects (enzyme deficiencies, receptor dysfunction, ion channel defects)

Search first: BRENDA, UniProt, KEGG, OMIM, PubMed
Epigenetic Changes: DNA methylation, histone modifications affecting gene expression in disease

Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
Molecular Profiling (if available):
Transcriptomics/gene expression changes > Search first: GEO (Gene Expression Omnibus), ArrayExpress, GTEx, Human Cell Atlas, SRA
Proteomics findings > Search first: PRIDE, ProteomeXchange, Human Protein Atlas, STRING, BioGRID
Metabolomics signatures > Search first: MetaboLights, Metabolomics Workbench, HMDB, METLIN
Lipidomics alterations > Search first: LIPID MAPS, SwissLipids, LipidHome, Metabolomics Workbench
Genomic structural features > Search first: UCSC Genome Browser, Ensembl, NCBI, dbVar, DGV
Advanced Technologies (if applicable):
Single-cell analysis findings (cell-type specific mechanisms, cellular heterogeneity) > Search first: Human Cell Atlas, Single Cell Portal, GEO, CELLxGENE
Spatial transcriptomics findings > Search first: GEO, Spatial Research, Vizgen, 10x Genomics data
Multi-omics integration results > Search first: TCGA, ICGC, cBioPortal, LinkedOmics, PubMed
Functional genomics screens (CRISPR, RNAi) > Search first: DepMap, GenomeRNAi, PubMed, BioGRID ORCS

For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types

7. Anatomical Structures Affected

Organ Level:
Primary organs directly affected
Secondary organ involvement (complications, secondary effects)
Body systems involved (cardiovascular, nervous, digestive, respiratory, endocrine, etc.)

Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT
Tissue and Cell Level:
Specific tissue types affected (epithelial, connective, muscle, nervous)
Specific cell populations targeted (with Cell Ontology terms)

Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB
Subcellular Level:
Cellular compartments involved (mitochondria, nucleus, ER, lysosomes) (with GO Cellular Component terms)

Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas
Localization:
Specific anatomical sites (with UBERON terms) > Search first: FMA, Uberon, NeuroNames (for brain), SNOMED CT
Lateralization (unilateral, bilateral, asymmetric) > Search first: HPO, clinical literature, imaging databases

8. Temporal Development

Onset:
Typical age of onset (congenital, pediatric, adult, geriatric)
Onset pattern (acute, subacute, chronic, insidious)

Search first: OMIM, Orphanet, HPO, PubMed
Progression:
Disease stages (early, intermediate, advanced, end-stage) > Search first: Cancer Staging Manual (AJCC), WHO classifications, PubMed
Progression rate (rapid, slow, variable)
Disease course pattern (episodic, relapsing-remitting, progressive, stable)
Disease duration (self-limited, chronic lifelong)

Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM
Patterns:
Remission patterns (spontaneous, treatment-induced) > Search first: Clinical trial databases, disease registries, PubMed
Critical periods (time windows of vulnerability or opportunity for intervention) > Search first: PubMed, developmental biology databases, clinical guidelines

9. Inheritance and Population

Epidemiology:
Prevalence (cases per 100,000 at given time)
Incidence (new cases per 100,000 per year)

Search first: Orphanet, CDC, WHO, GBD (Global Burden of Disease), national registries, SEER, disease registries
For Genetic Etiology:
Inheritance pattern (AD, AR, X-linked, mitochondrial, multifactorial, polygenic) > Search first: OMIM, Orphanet, ClinVar, GTR (Genetic Testing Registry)
Penetrance (complete, incomplete, age-dependent) > Search first: ClinVar, OMIM, PubMed, ClinGen
Expressivity (variable, consistent) > Search first: OMIM, ClinVar, PubMed
Genetic anticipation (increasing severity in successive generations) > Search first: OMIM, PubMed (especially for repeat expansion disorders)
Germline mosaicism > Search first: ClinVar, OMIM, genetic counseling literature, PubMed
Founder effects (population-specific mutations) > Search first: gnomAD, population genetics databases, PubMed
Consanguinity role > Search first: OMIM, population studies, genetic counseling resources
Carrier frequency > Search first: gnomAD, carrier screening databases, GeneReviews, GTR
Population Demographics:
Affected populations (ethnic or demographic groups with higher prevalence) > Search first: gnomAD, 1000 Genomes, PAGE Study, PubMed, population registries
Geographic distribution (endemic areas, regional variation) > Search first: WHO, CDC, GBD, Orphanet, geographic epidemiology databases
Geographic distribution of specific variants
Sex ratio (male:female) > Search first: Disease registries, OMIM, PubMed, epidemiological databases
Age distribution of affected individuals > Search first: CDC, disease registries, SEER, Orphanet

10. Diagnostics

Clinical Tests:
Laboratory tests (blood, urine, tissue chemistry, specific enzyme assays) > Search first: LOINC, LabTests Online, PubMed
Biomarkers (proteins, metabolites, genetic markers, circulating biomarkers) > Search first: FDA Biomarker List, BEST (Biomarkers, EndpointS, and other Tools), PubMed
Imaging studies (X-ray, CT, MRI, PET, ultrasound) > Search first: RadLex, DICOM, Radiopaedia, imaging databases
Functional tests (pulmonary function, cardiac stress tests) > Search first: LOINC, clinical guidelines, PubMed
Electrophysiology (EEG, EMG, ECG, nerve conduction studies) > Search first: LOINC, clinical neurophysiology databases, PubMed
Biopsy findings (histopathology, immunohistochemistry) > Search first: SNOMED CT, College of American Pathologists resources, PubMed
Pathology findings (microscopic examination) > Search first: SNOMED CT, Digital Pathology databases, PubMed
Genetic Testing:

Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen
Overview of recommended genetic testing approach
Whole genome sequencing (WGS) utility > Search first: GTR, ClinVar, GEL (Genomics England), gnomAD
Whole exome sequencing (WES) utility > Search first: GTR, ClinVar, OMIM, GeneMatcher
Gene panels (which panels, which genes) > Search first: GTR, ClinVar, laboratory-specific databases
Single gene testing > Search first: GTR, ClinVar, OMIM, GeneReviews
Chromosomal microarray (CMA) > Search first: DECIPHER, ClinVar, dbVar, ECARUCA
Karyotyping > Search first: Chromosome Abnormality Database, ClinVar, cytogenetics resources
FISH > Search first: ClinVar, cytogenetics databases, PubMed
Mitochondrial DNA testing > Search first: MITOMAP, MSeqDR, ClinVar, GTR
Repeat expansion testing > Search first: GTR, ClinVar, repeat expansion databases, PubMed
Omics-Based Diagnostics (if applicable):
RNA sequencing / transcriptomics > Search first: GEO, ArrayExpress, GTEx, RNA-seq databases
Proteomics > Search first: PRIDE, ProteomeXchange, FDA Biomarker database
Metabolomics > Search first: MetaboLights, Metabolomics Workbench, HMDB
Epigenomics > Search first: GEO, ENCODE, Roadmap Epigenomics, MethBase
Liquid biopsy > Search first: COSMIC, ClinVar, liquid biopsy databases, PubMed
Clinical Criteria:
Standardized diagnostic criteria (DSM, ICD, society guidelines) > Search first: DSM-5, ICD-11, clinical society guidelines, UpToDate
Differential diagnosis (other conditions to rule out, with distinguishing features) > Search first: DynaMed, UpToDate, clinical decision support systems
Screening:
Screening methods for asymptomatic individuals (newborn screening, carrier screening, cascade screening) > Search first: ACMG recommendations, CDC newborn screening, GTR

11. Outcome/Prognosis

Survival and Mortality:
Survival rate (5-year, 10-year, overall) > Search first: SEER, cancer registries, disease-specific registries, PubMed
Life expectancy (with and without treatment if applicable) > Search first: Orphanet, disease registries, actuarial databases, PubMed
Mortality rate > Search first: CDC, WHO, GBD, national mortality databases
Disease-specific mortality (deaths directly attributable to disease) > Search first: Disease registries, CDC Wonder, GBD, PubMed
Morbidity and Function:
Morbidity (disease-related disability and health impacts) > Search first: GBD, WHO, disability databases, PubMed
Disability outcomes (long-term functional impairments) > Search first: ICF (International Classification of Functioning), disability registries
Quality of life measures (EQ-5D, SF-36, PROMIS, disease-specific tools) > Search first: EQ-5D database, SF-36, PROMIS, PubMed
Disease Course:
Complications (secondary problems: infections, organ failure, etc.) > Search first: ICD codes, disease registries, clinical databases, PubMed
Recovery potential (likelihood and extent of recovery, with vs without treatment) > Search first: Natural history studies, rehabilitation databases, PubMed
Prediction:
Prognostic factors (age, disease severity, biomarkers, treatment response) > Search first: Prognostic models databases, clinical calculators, PubMed
Prognostic biomarkers (molecular markers predicting disease course) > Search first: FDA Biomarker database, PubMed, cancer prognostic databases

12. Treatment

Pharmacotherapy:
Pharmacological treatments (drug names, drug classes, mechanisms of action) > Search first: DrugBank, RxNorm, ATC classification, DailyMed, FDA databases
Pharmacogenomics (how genetic variants affect drug metabolism, efficacy, toxicity) > Search first: PharmGKB, CPIC (Clinical Pharmacogenetics), FDA Table of PGx Biomarkers
Advanced Therapeutics:
Gene therapy (viral vectors, CRISPR, gene replacement, gene editing) > Search first: ClinicalTrials.gov, FDA gene therapy database, ASGCT resources
Cell therapy (stem cell transplant, CAR-T, cellular therapeutics) > Search first: ClinicalTrials.gov, FDA cell therapy database, FACT standards
RNA-based therapies (ASOs, siRNA, mRNA therapies) > Search first: ClinicalTrials.gov, FDA approvals, PubMed
Targeted therapies (treatments directed at specific molecular targets) > Search first: My Cancer Genome, OncoKB, ClinicalTrials.gov, FDA approvals
Immunotherapies (checkpoint inhibitors, monoclonal antibodies) > Search first: Cancer Immunotherapy Database, FDA approvals, ClinicalTrials.gov
Surgical and Interventional:
Surgical interventions (types of surgery, timing, outcomes) > Search first: CPT codes, surgical registries, clinical guidelines, PubMed
Supportive and Rehabilitative:
Supportive care (symptom management, pain control, nutrition) > Search first: Clinical guidelines, Cochrane Library, PubMed
Rehabilitation (physical therapy, occupational therapy, speech therapy) > Search first: Rehabilitation medicine databases, clinical guidelines, PubMed
Experimental:
Experimental treatments in clinical trials (with NCT identifiers if available) > Search first: ClinicalTrials.gov, EU Clinical Trials Register, WHO ICTRP
Treatment Outcomes:
Treatment response rates > Search first: Clinical trial databases, FDA reviews, systematic reviews, PubMed
Side effects and adverse events > Search first: FDA Adverse Event Reporting System (FAERS), MedWatch, PubMed
Treatment Strategy:
Treatment algorithms (clinical pathways, decision trees) > Search first: Clinical practice guidelines, NCCN Guidelines, UpToDate
Combination therapies > Search first: ClinicalTrials.gov, treatment guidelines, PubMed
Personalized medicine approaches (genotype-guided treatment) > Search first: My Cancer Genome, CIViC, PharmGKB, precision medicine databases

For each treatment, suggest MAXO (Medical Action Ontology) terms where applicable.

13. Prevention

Prevention Levels:
Primary prevention (preventing disease occurrence: vaccination, risk factor modification) > Search first: CDC, WHO, USPSTF recommendations, Cochrane Library
Secondary prevention (early detection and treatment: screening programs, early intervention) > Search first: USPSTF, CDC screening guidelines, WHO
Tertiary prevention (preventing complications in those with disease) > Search first: Clinical guidelines, disease management protocols, PubMed
Immunization: Vaccine strategies (if applicable)

Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database
Screening and Early Detection:
Screening programs (population-based: newborn screening, cancer screening) > Search first: CDC screening programs, USPSTF, cancer screening databases
Genetic screening (carrier screening, preimplantation genetic diagnosis, prenatal testing) > Search first: ACMG recommendations, ACOG guidelines, GTR
Risk stratification (identifying high-risk individuals for targeted prevention) > Search first: Risk prediction models, clinical calculators, PubMed
Behavioral Interventions: Lifestyle modifications to reduce risk

Search first: CDC, WHO, behavioral intervention databases, Cochrane Library
Counseling: Genetic counseling (risk assessment, family planning guidance)

Search first: NSGC resources, ACMG guidelines, GeneReviews
Public Health:
Public health interventions (sanitation, vector control, health education) > Search first: CDC, WHO, public health databases, PubMed
Environmental interventions (reducing environmental risk factors) > Search first: EPA databases, WHO environmental health, PubMed
Prophylaxis: Preventive medications or procedures

Search first: Clinical guidelines, FDA approvals, PubMed

14. Other Species / Natural Disease

Taxonomy: Species affected (with NCBI Taxon identifiers)

Search first: NCBI Taxonomy
Breed: Specific breeds affected (with VBO identifiers if applicable)

Search first: VBO (Vertebrate Breed Ontology)
Gene: Orthologous genes in other species (with NCBI Gene IDs)

Search first: NCBI Gene
Natural Disease:
Naturally occurring disease in other species (companion animals, wildlife) > Search first: OMIA (Online Mendelian Inheritance in Animals), VetCompass, PubMed
Veterinary relevance and importance in animal health > Search first: OMIA, veterinary databases, PubMed
Comparative Biology:
Comparative pathology (similarities and differences across species) > Search first: OMIA, comparative pathology databases, PubMed
Evolutionary conservation of disease mechanisms > Search first: HomoloGene, OrthoMCL, Alliance of Genome Resources
Transmission (if applicable):
Zoonotic potential > Search first: CDC zoonotic diseases, WHO zoonoses, GIDEON
Cross-species susceptibility > Search first: NCBI Taxonomy, veterinary databases, PubMed

15. Model Organisms

Model Types:
Model organism type (mammalian, invertebrate, cellular, in vitro) > Search first: Alliance of Genome Resources, model organism databases
Specific model systems (mouse, rat, zebrafish, Drosophila, C. elegans, yeast, cell lines, organoids, iPSCs) > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, SGD, ATCC, Cellosaurus
Induced models (drug treatment, surgical intervention, environmental manipulation) > Search first: MGI, model organism databases, PubMed
Genetic Models:
Types available (knockout, knock-in, transgenic, conditional, humanized) > Search first: MGI, IMPC, KOMP, EuMMCR, IMSR
Model Characteristics:
Phenotype recapitulation (how well model reproduces human disease features) > Search first: Model organism databases, comparative studies, PubMed
Model limitations (aspects of human disease not captured) > Search first: Model organism databases, PubMed, review articles
Applications:
Research applications (what aspects of disease can be studied) > Search first: Model organism databases, PubMed
Resources:
Model databases > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, IMSR, EMMA, MMRRC

Citation Requirements

Cite primary literature (PMID preferred) for all mechanistic and clinical claims
Prioritize recent reviews and landmark papers
Include direct quotes from abstracts where possible to support key statements
Distinguish evidence source types: human clinical, model organism, in vitro, computational

Output Format

Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, MAXO, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease

This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (MAXO terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details

Comprehensive Disease Characteristics Report: Autosomal Recessive Osteopetrosis Type 2 (ARO2; TCIRG1-related)

1. Disease information

1.1 Overview / definition

Autosomal recessive osteopetrosis type 2 (ARO2) is a severe, typically infantile-onset osteoclast dysfunction disorder characterized by markedly increased bone density (“marble bone”) due to failure of osteoclast-mediated bone resorption, leading to bone marrow space obliteration (cytopenias) and narrowing of cranial nerve foramina (progressive visual/hearing impairment). (capo2022osteoclastrichosteopetrosis pages 1-2, penna2021autosomalrecessiveosteopetrosis pages 1-2, orchard2015hematopoieticstemcell pages 1-6)

1.2 Key identifiers (with URLs / dates when available)

MONDO:
Autosomal recessive osteopetrosis 2: MONDO:0009816 (via Open Targets disease ontology mapping). (OpenTargets Search: autosomal recessive osteopetrosis-TCIRG1)
Autosomal recessive osteopetrosis (broader): MONDO:0019026. (OpenTargets Search: autosomal recessive osteopetrosis-TCIRG1)
OMIM (disease): Infantile malignant autosomal recessive osteopetrosis / OPTB1: MIM 259700. (frattini2000defectsintcirg1 pages 1-2, capo2022osteoclastrichosteopetrosis pages 1-2)
OMIM (gene): TCIRG1: MIM 604592. (elkamah2023outliningtheclinical pages 1-2)
ICD-10: Osteopetrosis is referenced as ICD-10 M78.2 in a 2023 review (note: this is osteopetrosis broadly, not ARO2-specific). (nadyrshina2023clinicalgeneticaspects pages 1-2)
MeSH (ClinicalTrials.gov browse terms): Musculoskeletal Diseases (D009140), Bone Diseases (D001847), Hypocalcemia (D006996), Bone Marrow Failure Disorders (D000080983) are attached to a TCIRG1 gene-therapy trial record. (NCT04525352 chunk 1)

Not found in retrieved evidence: an explicit Orphanet identifier, ICD-11 code, and a single dedicated MeSH descriptor for “osteopetrosis” within the retrieved texts.

1.3 Synonyms / alternative names

Common alternative names and labels include: - Infantile malignant osteopetrosis (frattini2000defectsintcirg1 pages 1-2, capo2022osteoclastrichosteopetrosis pages 1-2) - Autosomal recessive malignant osteopetrosis (arOP) (frattini2000defectsintcirg1 pages 1-2) - Autosomal recessive osteopetrosis (ARO) (capo2022osteoclastrichosteopetrosis pages 1-2) - OPTB1 / TCIRG1 osteopetrosis (OPTB1 subgroup) (capo2022osteoclastrichosteopetrosis pages 1-2)

1.4 Evidence origin (individual vs aggregated)

The report integrates aggregated disease-level resources (e.g., Open Targets MONDO mappings) (OpenTargets Search: autosomal recessive osteopetrosis-TCIRG1), registry-based transplant cohorts (CIBMTR/EBMT referenced in reviews and primary studies) (orchard2015hematopoieticstemcell pages 1-6, capo2022osteoclastrichosteopetrosis pages 5-6), and individual/cohort clinical genetics series (e.g., Egyptian pedigrees) (elkamah2023outliningtheclinical pages 4-7).

2. Etiology

2.1 Primary causal factors

ARO2 is caused by biallelic loss-of-function variants in TCIRG1, which encodes the a3 subunit of the osteoclast vacuolar H+-ATPase (V-ATPase) V0 sector, required for acidification of the resorption lacuna and thus mineral dissolution and matrix degradation during bone resorption. (capo2022osteoclastrichosteopetrosis pages 1-2, frattini2000defectsintcirg1 pages 1-2, penna2024correctionofosteopetrosis pages 1-2)

Primary literature milestone: Frattini et al. (Nature Genetics, 2000) demonstrated that TCIRG1 is mutated in a substantial subset of patients with infantile malignant ARO and connects TCIRG1/OC116 to osteoclast lacunar acidification. Direct abstract/text quote: “Infantile malignant autosomal recessive osteopetrosis (MIM 259700) is a severe bone disease with a fatal outcome, generally within the first decade of life… Here we show that TCIRG1, encoding the osteoclast-specific 116-kD subunit of the vacuolar proton pump, is mutated…” (frattini2000defectsintcirg1 pages 1-2)

2.2 Risk factors

Genetic: Having biallelic pathogenic TCIRG1 variants is causal. High rates of consanguinity can increase disease occurrence; in one TCIRG1 cohort, 90% of probands were from consanguineous families. (elkamah2023outliningtheclinical pages 4-7)
Environmental: No specific environmental risk factor is established in the retrieved evidence for this Mendelian disorder.

2.3 Protective factors

No validated genetic or environmental protective factors were identified in the retrieved evidence.

2.4 Gene–environment interactions

No specific gene–environment interactions were identified in the retrieved evidence.

3. Phenotypes (with suggested HPO terms)

3.1 Core phenotype spectrum (TCIRG1-related malignant/infantile ARO)

Phenotypes span skeletal, hematologic, neurologic/cranial nerve, dental, and metabolic domains, consistent with “osteoclast-rich” osteopetrosis where osteoclasts are present but nonfunctional. (capo2022osteoclastrichosteopetrosis pages 1-2, penna2021autosomalrecessiveosteopetrosis pages 1-2)

3.2 Phenotype frequencies from a 2023 TCIRG1 cohort (Egyptian families; n=16 affected)

Reported frequencies (useful for knowledge-base quantitative annotations): - Frontal bossing: 16/16 (100%) → HPO: Frontal bossing (HP:0002007) (elkamah2023outliningtheclinical pages 4-7) - History of fractures: 15/16 (94%) → HPO: Bone fracture (HP:0002653) (elkamah2023outliningtheclinical pages 4-7) - Short stature: 13/16 (81%) → HPO: Short stature (HP:0004322) (elkamah2023outliningtheclinical pages 4-7) - Macrocephaly: 13/16 (81%) → HPO: Macrocephaly (HP:0000256) (elkamah2023outliningtheclinical pages 4-7) - Anemia: 12/16 (75%) → HPO: Anemia (HP:0001903) (elkamah2023outliningtheclinical pages 4-7) - Hepatosplenomegaly: 9/16 (56%) → HPO: Hepatosplenomegaly (HP:0002240) (elkamah2023outliningtheclinical pages 4-7) - Neurological deficit: 8/16 (50%), including developmental delay (25%), facial palsy (6.25%), deafness (12.5%), blindness (6.25%) → HPO: Global developmental delay (HP:0001263), Facial palsy (HP:0007209), Hearing impairment (HP:0000365), Blindness (HP:0000618) (elkamah2023outliningtheclinical pages 4-7) - Additional reported: cardiac anomalies 2/16 (12.5%), renal effects 1/16 (6%). (elkamah2023outliningtheclinical pages 4-7)

Dental findings were described in only 4 examined individuals (interpret cautiously): delayed eruption, enamel hypocalcification, high-arched palate, gingival recession, premature loss of deciduous teeth. Suggested HPO terms include Delayed eruption of teeth (HP:0006347), Abnormality of dental enamel (HP:0000682), High arched palate (HP:0000218), Gingival recession (HP:0030811), Premature loss of deciduous teeth (HP:0006293). (elkamah2023outliningtheclinical pages 4-7)

3.3 Radiologic hallmark phenotypes (HPO) and supporting figure

Radiographic features include generalized osteosclerosis/increased bone density, Erlenmeyer flask deformity, “bone-in-bone” appearance, straight mandibular angle, and acro-osteolysis. (elkamah2023outliningtheclinical pages 4-7)

Visual evidence: A multi-panel figure from the 2023 cohort displays these radiologic hallmarks (frontal bossing, increased density, Erlenmeyer flask deformity, bone-in-bone, acro-osteolysis). (elkamah2023outliningtheclinical media d9a10b41)

Suggested HPO terms: Increased bone density (HP:0010927), Erlenmeyer flask deformity (HP:0005612), Bone-in-bone appearance (HP:0002654), Acro-osteolysis (HP:0009777), Abnormal mandibular morphology (HP:0000303). (elkamah2023outliningtheclinical media d9a10b41, elkamah2023outliningtheclinical pages 4-7)

3.4 Age of onset, severity, progression

Presentation is typically in early infancy (e.g., “usually from 2.5 to 6 months-of-age” in a TCIRG1-focused review). (capo2022osteoclastrichosteopetrosis pages 1-2) The course is progressive and severe, with high risk of early mortality without curative treatment. (orchard2015hematopoieticstemcell pages 1-6, balemans2005aclinicaland pages 1-2)

3.5 Quality-of-life impact

Quality-of-life is substantially impaired by transfusion dependence, fractures, infections, and progressive sensory loss; post-HSCT cohorts show persistent high rates of visual impairment among survivors (see Prognosis). (capo2022osteoclastrichosteopetrosis pages 5-6, orchard2015hematopoieticstemcell pages 1-6)

4. Genetic / molecular information

4.1 Causal gene(s)

TCIRG1 (V-ATPase V0 subunit a3; osteoclast-specific OC116 isoform) is the principal causal gene for ARO2/OPTB1. (frattini2000defectsintcirg1 pages 1-2, capo2022osteoclastrichosteopetrosis pages 1-2)

4.2 Pathogenic variant types and recent variant series

Multiple variant classes occur (missense, nonsense, frameshift, splice, deletions). Landmark cases include splice and frameshift/nonsense variants reported in the original Nature Genetics study. (frattini2000defectsintcirg1 pages 1-2)

A 2023 Egyptian series reported 14 TCIRG1 variants including 5 novel across affected individuals and fetuses; notably, a missense variant p.Pro775Arg was frequent in that cohort (7/16; 44%). (elkamah2023outliningtheclinical pages 4-7)

4.3 Functional consequence

The dominant mechanism is loss of function leading to failure of osteoclast lacunar acidification and ruffled border/secretory lysosome trafficking, producing “osteoclast-rich” but non-resorbing osteoclasts. (capo2022osteoclastrichosteopetrosis pages 1-2, capo2022osteoclastrichosteopetrosis pages 3-3)

4.4 Modifier genes / epigenetics / chromosomal abnormalities

No validated modifier genes, epigenetic signatures, or recurrent chromosomal abnormalities specific to ARO2 were identified in the retrieved evidence.

5. Environmental information

No established environmental toxins, lifestyle factors, or infectious triggers were identified in the retrieved evidence for this Mendelian osteoclast disorder.

6. Mechanism / pathophysiology

6.1 Core causal chain (upstream → downstream)

1) Biallelic TCIRG1 loss-of-function → 2) defective V-ATPase a3–dependent proton pumping in osteoclast ruffled border and impaired secretory lysosome trafficking → 3) failure to acidify resorption lacuna (hydroxyapatite dissolution impaired) → 4) impaired bone resorption despite abundant multinucleated osteoclasts (“osteoclast-rich osteopetrosis”) → 5) progressive bone sclerosis and failure to remodel → 6) marrow space obliteration and fibrosis causing cytopenias and extramedullary hematopoiesis → 7) cranial foramina narrowing causing progressive cranial nerve compression (vision/hearing loss) and other complications. (capo2022osteoclastrichosteopetrosis pages 1-2, frattini2000defectsintcirg1 pages 1-2, penna2021autosomalrecessiveosteopetrosis pages 1-2)

Direct quote supporting the mechanistic role of TCIRG1/OC116: the Nature Genetics paper explains that V-ATPase mediates H+ transport into the resorption lacunae “where a low pH is a prerequisite for the dissolution of hydroxyapatite crystals.” (frattini2000defectsintcirg1 pages 1-2)

6.2 Cell types (CL terms suggestions)

Osteoclast (CL:0000092)
Hematopoietic stem cell (CL:0000037) / hematopoietic progenitor cells
Monocyte/macrophage lineage cells (osteoclast precursors)
Mesenchymal stromal cell (for niche alterations)

Support: patient-derived iPSC models show skewing in hematopoietic differentiation and niche-factor dysregulation relevant to engraftment biology. (zeytin2022alterationsinhematopoietic pages 1-2)

6.3 Biological process and cellular component suggestions (GO)

GO:0031589 (cell-substrate adhesion) and osteoclast cytoskeletal organization (ruffled border)
GO:0031929 (TOR signaling—general osteoclast biology; not directly evidenced here)
More directly relevant (term names): osteoclast differentiation, bone resorption, proton transmembrane transport, lysosomal transport/secretory lysosome trafficking, extramedullary hematopoiesis

6.4 Bone marrow niche mechanism (engraftment relevance)

Patient-derived iPSC systems suggest that osteopetrosis involves disruption of both hematopoietic progenitor and mesenchymal stromal compartments, including altered expression of niche factors (Sdf-1, Jagged-1, Kit-L, Opn) that can be partially restored by coculture with healthy cells, providing a mechanistic basis for engraftment challenges after transplantation. (zeytin2022alterationsinhematopoietic pages 1-2)

6.5 Molecular profiling / multi-omics

No reproducible transcriptomic/proteomic/metabolomic signatures specific to ARO2 were identified in the retrieved evidence.

7. Anatomical structures affected (UBERON suggestions)

7.1 Organ/system level

Skeletal system (bones throughout the body; diffuse osteosclerosis) (capo2022osteoclastrichosteopetrosis pages 1-2)
Bone marrow / hematopoietic system (marrow cavity fibrosis/insufficient hematopoiesis) (orchard2015hematopoieticstemcell pages 1-6, capo2022osteoclastrichosteopetrosis pages 5-6)
Nervous system (cranial nerves; optic nerve) due to skull foramina narrowing/impingement (orchard2015hematopoieticstemcell pages 1-6, capo2022osteoclastrichosteopetrosis pages 1-2)
Liver and spleen (hepatosplenomegaly from extramedullary hematopoiesis) (orchard2015hematopoieticstemcell pages 1-6, elkamah2023outliningtheclinical pages 4-7)

7.2 Tissue/cell level

Mineralized bone and osteoclast-bone interface (osteoclast ruffled border, resorption lacuna)

7.3 Subcellular level (GO-CC suggestions)

V-ATPase complex
Lysosome / secretory lysosome
Ruffled border membrane domain

Support: TCIRG1 is a V-ATPase component essential for lacunar acidification and trafficking. (capo2022osteoclastrichosteopetrosis pages 1-2, frattini2000defectsintcirg1 pages 1-2)

8. Temporal development

8.1 Onset

Infantile onset is typical, reported around 2.5–6 months for severe TCIRG1-related ARO. (capo2022osteoclastrichosteopetrosis pages 1-2)

8.2 Progression

Progressive bone sclerosis and expanding skeletal tissue encroach on marrow and nerve foramina, leading to worsening cytopenias and neurologic deficits. (orchard2015hematopoieticstemcell pages 1-6, penna2021autosomalrecessiveosteopetrosis pages 1-2)

8.3 Critical period

Multiple sources emphasize the importance of very early definitive therapy (HSCT or potential gene therapy) to prevent irreversible cranial nerve damage. (capo2020expandedcirculatinghematopoietic pages 1-6, capo2022osteoclastrichosteopetrosis pages 5-6)

9. Inheritance and population

9.1 Inheritance

Autosomal recessive inheritance; affected individuals typically have biallelic pathogenic TCIRG1 variants. (capo2022osteoclastrichosteopetrosis pages 1-2, frattini2000defectsintcirg1 pages 1-2)

9.2 Epidemiology (statistics)

Incidence estimates for ARO overall: ~1:250,000 live births. (nadyrshina2023clinicalgeneticaspects pages 1-2, penna2021autosomalrecessiveosteopetrosis pages 1-2)
Historical epidemiology for malignant ARO cited in a classic overview: ~1:200,000–1:300,000 average incidence; and a reported much higher local incidence in Costa Rica (3.4 per 100,000). (balemans2005aclinicaland pages 1-2)

9.3 Population factors

Founder effects/consanguinity can increase incidence in specific regions (e.g., Costa Rica, Middle East, Chuvash Republic) and consanguinity can be common in some cohorts. (capo2022osteoclastrichosteopetrosis pages 1-2, elkamah2023outliningtheclinical pages 4-7)

10. Diagnostics

10.1 Clinical evaluation

Red flags include early-onset macrocephaly/frontal bossing, fractures, failure to thrive, hepatosplenomegaly, cytopenias/infections/bleeding, and early visual impairment (nystagmus, inability to track). (orchard2015hematopoieticstemcell pages 1-6, elkamah2023outliningtheclinical pages 4-7)

10.2 Laboratory findings

Cytopenias and marrow failure: anemia and thrombocytopenia are common; leukoerythroblastoid peripheral smear (nucleated RBCs, dacrocytes) can reflect marrow fibrosis. (capo2022osteoclastrichosteopetrosis pages 5-6, elkamah2023outliningtheclinical pages 4-7)
Metabolic derangements may include hypocalcemia and osteopetrorickets. (capo2022osteoclastrichosteopetrosis pages 1-2, penna2021autosomalrecessiveosteopetrosis pages 1-2)

10.3 Imaging

Characteristic radiographs show diffuse osteosclerosis/increased density with classic signs (Erlenmeyer flask deformity, bone-in-bone, skull base sclerosis). (elkamah2023outliningtheclinical pages 4-7, chen2023casereportgene pages 4-5)

10.4 Pathology

Bone marrow biopsy may show marrow fibrosis and abundant (but dysfunctional) osteoclasts; trabecular bone calcification can be prominent. (frattini2000defectsintcirg1 pages 1-2, chen2023casereportgene pages 1-2)

10.5 Genetic testing

Approaches in recent clinical genetics reports include: - Targeted TCIRG1 sequencing (coding exons and exon–intron boundaries) using Sanger methods and reference sequences, used for diagnosis, carrier testing, and prenatal diagnosis. (elkamah2023outliningtheclinical pages 2-4) - Whole-exome sequencing (WES) with ACMG interpretation and gnomAD filtering to identify biallelic TCIRG1 variants and distinguish TCIRG1 hematologic-predominant phenotypes from neurodegenerative forms (e.g., OSTM1/CLCN7). (sahinoglu2025theclinicaland pages 1-2)

10.6 Differential diagnosis

Conditions with overlapping presentations include other genetic osteopetroses (e.g., CLCN7, OSTM1, CA2) and hematologic disorders with cytopenias; one report notes overlap prompting consideration of juvenile myelomonocytic leukemia (JMML) and leukocyte adhesion deficiency (LAD) in differential diagnosis. (wang2023anovelcompound pages 1-2)

11. Outcome / prognosis

11.1 Natural history without definitive therapy

Untreated ARO has high mortality; one transplant-cohort background statement reports ~70% mortality by age 6 years, primarily from marrow failure. (orchard2015hematopoieticstemcell pages 1-6)
A classic overview reports ~75% mortality by age 4 in malignant ARO (historical data). (balemans2005aclinicaland pages 1-2)

11.2 Outcomes after HSCT (real-world evidence)

From a large international series of 193 infants transplanted 1990–2011: - 5- and 10-year survival: 62%/62% after HLA-matched sibling vs 42%/39% after alternative donors. (orchard2015hematopoieticstemcell pages 1-6) - Graft failure was the leading cause of death (50% of matched-sibling deaths; 43% of alternative-donor deaths). (orchard2015hematopoieticstemcell pages 10-14) - Among evaluable survivors: 70% visually impaired and 10% had impaired hearing and gross motor delay. (orchard2015hematopoieticstemcell pages 1-6)

A single-center haploidentical HSCT series (n=27) reported 5-year overall survival 73.9%, with frequent but mostly mild acute GVHD and substantial infection burden; some sensory outcomes improved but often incompletely. (zhu2021haploidenticalhaematopoieticstem pages 4-5)

11.3 Prognostic factors

Donor type is a key determinant of survival in the large CIBMTR series. (orchard2015hematopoieticstemcell pages 1-6) Pre-existing neurologic damage (e.g., vision loss) is clinically emphasized as a reason for early referral. (capo2022osteoclastrichosteopetrosis pages 5-6)

12. Treatment

12.1 Standard of care: allogeneic HSCT

HSCT corrects disease because osteoclasts derive from hematopoietic progenitors; functional osteoclast differentiation after transplant can restore remodeling and reverse pancytopenia/extramedullary hematopoiesis. (orchard2015hematopoieticstemcell pages 1-6)

Key outcome statistics and complications are summarized in the Prognosis section and include graft failure, VOD, interstitial pneumonitis, pulmonary hypertension, and calcium disturbances. (orchard2015hematopoieticstemcell pages 10-14, capo2022osteoclastrichosteopetrosis pages 5-6)

MAXO suggestions (term names): Hematopoietic stem cell transplantation; Allogeneic bone marrow transplantation; Myeloablative conditioning regimen; GVHD prophylaxis; Supportive transfusion therapy.

12.2 Supportive / symptomatic care

Supportive management includes calcium/vitamin D management (osteopetrorickets), transfusions, antimicrobials, orthopedic and neurosurgical management, and pain management, but is not curative. (capo2022osteoclastrichosteopetrosis pages 5-6)

Interferon-γ-1b: A review notes that interferon gamma-1b had reduced tolerability and did not improve bone mineral density in reported use/trial context (with reference to a clinical study). (capo2022osteoclastrichosteopetrosis pages 5-6)

12.3 Emerging/experimental: autologous gene therapy for TCIRG1

12.3.1 Clinical trial (terminated)

NCT04525352 (Rocket Pharmaceuticals; UCLA; Phase 1; start 2020-11-19; status terminated; last update posted 2022-07-13) evaluated autologous CD34+ cells transduced ex vivo with a lentiviral vector encoding TCIRG1 (RP-L401) after myeloablative conditioning; discontinued due to feasibility. (NCT04525352 chunk 1) ClinicalTrials.gov URL: https://clinicaltrials.gov/study/NCT04525352 (NCT04525352 chunk 1)

12.3.2 2024 preclinical development (priority recent source)

A 2024 oc/oc neonatal mouse study reports that lentiviral gene therapy “can revert the osteopetrotic bone phenotype, allowing long-term survival and reducing extramedullary haematopoiesis,” and explores plerixafor mobilization and non-genotoxic conditioning to enable clinical translation in very young patients. (penna2024correctionofosteopetrosis pages 1-2)

MAXO suggestions (term names): Gene therapy; Ex vivo gene transfer; Autologous hematopoietic stem cell transplantation.

13. Prevention

Primary prevention is not applicable in the usual sense for a Mendelian disorder, but genetic counseling, carrier detection, and prenatal diagnosis are key preventive strategies. A 2023 TCIRG1 cohort reports use of carrier detection and prenatal diagnosis (amniotic fluid testing) enabling informed reproductive decisions. (elkamah2023outliningtheclinical pages 2-4)

14. Other species / natural disease

No naturally occurring TCIRG1 osteopetrosis in non-mouse species was identified in the retrieved evidence.

15. Model organisms and experimental models

15.1 Mouse models

oc/oc mouse (spontaneous Tcirg1 deletion): classic, severe osteopetrosis model; used widely for mechanistic studies and therapeutic development. (palagano2020generationofan pages 1-2, penna2024correctionofosteopetrosis pages 1-2)
Targeted Tcirg1/Atp6i disruption models have also been used for pathogenesis and therapy development. (capo2022osteoclastrichosteopetrosis pages 1-2)
NSG oc/oc (immunodeficient) model: developed to permit xenotransplantation; neonatal murine bone marrow transplant can rescue, but human CD34+ xenografts did not ameliorate bone pathology in reported work, highlighting rapid/severe course as a limitation. (palagano2020generationofan pages 1-2)

15.2 Patient-derived cellular models

Patient iPSC-derived osteoclasts recapitulate functional defects (reduced CTSK/TRAP expression and reduced pit formation) and demonstrate rescue by transgenic TCIRG1 restoration, supporting proof-of-concept for autologous correction. (chen2019tcirg1transgenicrescue pages 1-3)
iPSC-based niche models demonstrate defects in hematopoietic and mesenchymal stromal compartments that may relate to engraftment. (zeytin2022alterationsinhematopoietic pages 1-2)

15.3 Applications and limitations

These models are used to (i) validate causality and mechanism (acidification/resorption defects), (ii) optimize HSCT conditioning and engraftment strategies, and (iii) develop/test gene therapy approaches. Major limitations include rapid lethality of severe mouse models and incomplete support for human osteoclast differentiation in xenograft settings. (palagano2020generationofan pages 1-2, penna2021autosomalrecessiveosteopetrosis pages 6-7)

Key recent developments (2023–2024 prioritized)

2023: Detailed TCIRG1 cohort with phenotype frequencies, consanguinity patterns, and expanded variant spectrum (including novel variants). (elkamah2023outliningtheclinical pages 4-7)
2024: Preclinical optimization of lentiviral TCIRG1 gene therapy in neonatal oc/oc mice, including mobilization and non-genotoxic conditioning strategies relevant to real-world translation. (penna2024correctionofosteopetrosis pages 1-2)

Limitations of this report (due to retrieved evidence)

Explicit Orphanet ID, ICD-11, and a dedicated MeSH descriptor for osteopetrosis were not present in the retrieved sources.
Variant allele frequencies in population databases (gnomAD) and ClinVar classifications were described as part of methods in some reports but were not extractable as concrete per-variant AF numbers from the retrieved excerpts.
Naturally occurring non-mouse animal cases were not identified within the retrieved evidence.

References

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(penna2021autosomalrecessiveosteopetrosis pages 1-2): Sara Penna, Anna Villa, and Valentina Capo. Autosomal recessive osteopetrosis: mechanisms and treatments. Disease Models & Mechanisms, May 2021. URL: https://doi.org/10.1242/dmm.048940, doi:10.1242/dmm.048940. This article has 70 citations and is from a domain leading peer-reviewed journal.
(orchard2015hematopoieticstemcell pages 1-6): Paul J. Orchard, Anders L. Fasth, Jennifer Le Rademacher, Wensheng He, Jaap Jan Boelens, Edwin M. Horwitz, Amal Al-Seraihy, Mouhab Ayas, Carmem M. Bonfim, Farid Boulad, Troy Lund, David K. Buchbinder, Neena Kapoor, Tracey A. O’Brien, Miguel A. Diaz Perez, Paul A. Veys, and Mary Eapen. Hematopoietic stem cell transplantation for infantile osteopetrosis. Blood, 126 2:270-6, Jul 2015. URL: https://doi.org/10.1182/blood-2015-01-625541, doi:10.1182/blood-2015-01-625541. This article has 130 citations and is from a highest quality peer-reviewed journal.
(OpenTargets Search: autosomal recessive osteopetrosis-TCIRG1): Open Targets Query (autosomal recessive osteopetrosis-TCIRG1, 6 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.
(frattini2000defectsintcirg1 pages 1-2): Annalisa Frattini, Paul J. Orchard, Cristina Sobacchi, Silvia Giliani, Mario Abinun, Jan P. Mattsson, David J. Keeling, Ann-Katrin Andersson, Pia Wallbrandt, Luigi Zecca, Luigi D. Notarangelo, Paolo Vezzoni, and Anna Villa. Defects in tcirg1 subunit of the vacuolar proton pump are responsible for a subset of human autosomal recessive osteopetrosis. Nature Genetics, 25:343-346, Jul 2000. URL: https://doi.org/10.1038/77131, doi:10.1038/77131. This article has 871 citations and is from a highest quality peer-reviewed journal.
(elkamah2023outliningtheclinical pages 1-2): Ghada Y. El-Kamah, Mennat I. Mehrez, Mohamed B. Taher, Hala T. El-Bassyouni, Khaled R. Gaber, and Khalda S. Amr. Outlining the clinical profile of tcirg1 14 variants including 5 novels with overview of aro phenotype and ethnic impact in 20 egyptian families. Genes, 14:900, Apr 2023. URL: https://doi.org/10.3390/genes14040900, doi:10.3390/genes14040900. This article has 4 citations.
(nadyrshina2023clinicalgeneticaspects pages 1-2): D. D. Nadyrshina and R. I. Khusainova. Clinical, genetic aspects and molecular pathogenesis of osteopetrosis. Vavilov Journal of Genetics and Breeding, 27:383-392, Jul 2023. URL: https://doi.org/10.18699/vjgb-23-46, doi:10.18699/vjgb-23-46. This article has 13 citations.
(NCT04525352 chunk 1): A Trial to Evaluate Safety and Efficacy of RP-L401-0120 in Subjects With Infantile Malignant Osteopetrosis. Rocket Pharmaceuticals Inc.. 2020. ClinicalTrials.gov Identifier: NCT04525352
(capo2022osteoclastrichosteopetrosis pages 5-6): Valentina Capo, Mario Abinun, and Anna Villa. Osteoclast rich osteopetrosis due to defects in the tcirg1 gene. Bone, 165:116519, Dec 2022. URL: https://doi.org/10.1016/j.bone.2022.116519, doi:10.1016/j.bone.2022.116519. This article has 26 citations and is from a domain leading peer-reviewed journal.
(elkamah2023outliningtheclinical pages 4-7): Ghada Y. El-Kamah, Mennat I. Mehrez, Mohamed B. Taher, Hala T. El-Bassyouni, Khaled R. Gaber, and Khalda S. Amr. Outlining the clinical profile of tcirg1 14 variants including 5 novels with overview of aro phenotype and ethnic impact in 20 egyptian families. Genes, 14:900, Apr 2023. URL: https://doi.org/10.3390/genes14040900, doi:10.3390/genes14040900. This article has 4 citations.
(penna2024correctionofosteopetrosis pages 1-2): Sara Penna, Alessandra Zecchillo, Martina Di Verniere, Elena Fontana, Valeria Iannello, Eleonora Palagano, Stefano Mantero, Andrea Cappelleri, Elena Rizzoli, Ludovica Santi, Laura Crisafulli, Marta Filibian, Antonella Forlino, Luca Basso-Ricci, Serena Scala, Eugenio Scanziani, Thorsten Schinke, Francesca Ficara, Cristina Sobacchi, Anna Villa, and Valentina Capo. Correction of osteopetrosis in the neonate oc/oc murine model after lentiviral vector gene therapy and non-genotoxic conditioning. Frontiers in Endocrinology, Sep 2024. URL: https://doi.org/10.3389/fendo.2024.1450349, doi:10.3389/fendo.2024.1450349. This article has 6 citations.
(elkamah2023outliningtheclinical media d9a10b41): Ghada Y. El-Kamah, Mennat I. Mehrez, Mohamed B. Taher, Hala T. El-Bassyouni, Khaled R. Gaber, and Khalda S. Amr. Outlining the clinical profile of tcirg1 14 variants including 5 novels with overview of aro phenotype and ethnic impact in 20 egyptian families. Genes, 14:900, Apr 2023. URL: https://doi.org/10.3390/genes14040900, doi:10.3390/genes14040900. This article has 4 citations.
(balemans2005aclinicaland pages 1-2): W. Balemans, L. Van Wesenbeeck, and W. Van Hul. A clinical and molecular overview of the human osteopetroses. Calcified Tissue International, 77:263-274, Nov 2005. URL: https://doi.org/10.1007/s00223-005-0027-6, doi:10.1007/s00223-005-0027-6. This article has 204 citations and is from a peer-reviewed journal.
(capo2022osteoclastrichosteopetrosis pages 3-3): Valentina Capo, Mario Abinun, and Anna Villa. Osteoclast rich osteopetrosis due to defects in the tcirg1 gene. Bone, 165:116519, Dec 2022. URL: https://doi.org/10.1016/j.bone.2022.116519, doi:10.1016/j.bone.2022.116519. This article has 26 citations and is from a domain leading peer-reviewed journal.
(zeytin2022alterationsinhematopoietic pages 1-2): Inci Cevher Zeytin, Berna Alkan, Cansu Ozdemir, Duygu Uckan Cetinkaya, and Fatma Visal Okur. Alterations in hematopoietic and mesenchymal stromal cell components of the osteopetrotic bone marrow niche. Stem Cells Translational Medicine, 11:310-321, Mar 2022. URL: https://doi.org/10.1093/stcltm/szab019, doi:10.1093/stcltm/szab019. This article has 10 citations and is from a domain leading peer-reviewed journal.
(capo2020expandedcirculatinghematopoietic pages 1-6): Valentina Capo, Sara Penna, Ivan Merelli, Matteo Barcella, Serena Scala, Luca Basso-Ricci, Elena Draghici, Eleonora Palagano, Erika Zonari, Giacomo Desantis, Paolo Uva, Roberto Cusano, Lucia Sergi Sergi, Laura Crisafulli, Despina Moshous, Polina Stepensky, Katarzyna Drabko, Zühre Kaya, Ekrem Unal, Alper Gezdirici, Giuseppe Menna, Marta Serafini, Alessandro Aiuti, Silvia Laura Locatelli, Carmelo Carlo-Stella, Ansgar S. Schulz, Francesca Ficara, Cristina Sobacchi, Bernhard Gentner, and Anna Villa. Expanded circulating hematopoietic stem/ progenitor cells as novel cell source for the treatment of tcirg1 osteopetrosis. Haematologica, 106:74-86, Jan 2020. URL: https://doi.org/10.3324/haematol.2019.238261, doi:10.3324/haematol.2019.238261. This article has 36 citations.
(chen2023casereportgene pages 4-5): Yu Chen, Lina Zhou, Xianmin Guan, Xianhao Wen, Jie Yu, and Ying Dou. Case report: gene mutations and clinical characteristics of four patients with osteopetrosis. Frontiers in Pediatrics, Mar 2023. URL: https://doi.org/10.3389/fped.2023.1096770, doi:10.3389/fped.2023.1096770. This article has 10 citations.
(chen2023casereportgene pages 1-2): Yu Chen, Lina Zhou, Xianmin Guan, Xianhao Wen, Jie Yu, and Ying Dou. Case report: gene mutations and clinical characteristics of four patients with osteopetrosis. Frontiers in Pediatrics, Mar 2023. URL: https://doi.org/10.3389/fped.2023.1096770, doi:10.3389/fped.2023.1096770. This article has 10 citations.
(elkamah2023outliningtheclinical pages 2-4): Ghada Y. El-Kamah, Mennat I. Mehrez, Mohamed B. Taher, Hala T. El-Bassyouni, Khaled R. Gaber, and Khalda S. Amr. Outlining the clinical profile of tcirg1 14 variants including 5 novels with overview of aro phenotype and ethnic impact in 20 egyptian families. Genes, 14:900, Apr 2023. URL: https://doi.org/10.3390/genes14040900, doi:10.3390/genes14040900. This article has 4 citations.
(sahinoglu2025theclinicaland pages 1-2): Esra Pekpak Şahinoğlu, Ayşe Ceyda Ören, Bahtiyar Şahinoğlu, Uğur Gümüş, Çağrı Damar, Mehmet Keskin, and Sinan Akbayram. The clinical and genetic spectrum of infantile osteopetrosis: a single-center experience including a novel tcirg1 mutation. Trends in Pediatrics, 6:151-158, Sep 2025. URL: https://doi.org/10.59213/tp.2025.249, doi:10.59213/tp.2025.249. This article has 0 citations.
(wang2023anovelcompound pages 1-2): Xia Wang, Yingcan Wang, Ting Xu, Yanjie Fan, Yifeng Ding, and Jihong Qian. A novel compound heterozygous mutation of the clcn7 gene is associated with autosomal recessive osteopetrosis. Frontiers in Pediatrics, Apr 2023. URL: https://doi.org/10.3389/fped.2023.978879, doi:10.3389/fped.2023.978879. This article has 5 citations.
(orchard2015hematopoieticstemcell pages 10-14): Paul J. Orchard, Anders L. Fasth, Jennifer Le Rademacher, Wensheng He, Jaap Jan Boelens, Edwin M. Horwitz, Amal Al-Seraihy, Mouhab Ayas, Carmem M. Bonfim, Farid Boulad, Troy Lund, David K. Buchbinder, Neena Kapoor, Tracey A. O’Brien, Miguel A. Diaz Perez, Paul A. Veys, and Mary Eapen. Hematopoietic stem cell transplantation for infantile osteopetrosis. Blood, 126 2:270-6, Jul 2015. URL: https://doi.org/10.1182/blood-2015-01-625541, doi:10.1182/blood-2015-01-625541. This article has 130 citations and is from a highest quality peer-reviewed journal.
(zhu2021haploidenticalhaematopoieticstem pages 4-5): Guanghua Zhu, Ang Wei, Bin Wang, Jun Yang, Yan Yan, Kai Wang, Chenguang Jia, Yanhui Luo, Sidan Li, Xuan Zhou, Tianyou Wang, Huyong Zheng, and Maoquan Qin. Haploidentical haematopoietic stem cell transplantation for malignant infantile osteopetrosis and intermediate osteopetrosis: a retrospective analysis of a single centre. Orphanet Journal of Rare Diseases, Jul 2021. URL: https://doi.org/10.1186/s13023-021-01955-6, doi:10.1186/s13023-021-01955-6. This article has 11 citations and is from a peer-reviewed journal.
(palagano2020generationofan pages 1-2): Eleonora Palagano, Sharon Muggeo, Laura Crisafulli, Irina L. Tourkova, Dario Strina, Stefano Mantero, Elena Fontana, Silvia L. Locatelli, Marta Monari, Emanuela Morenghi, Carmelo Carlo-Stella, John B. Barnett, Harry C. Blair, Paolo Vezzoni, Anna Villa, Cristina Sobacchi, and Francesca Ficara. Generation of an immunodeficient mouse model of tcirg1-deficient autosomal recessive osteopetrosis. Bone Reports, 12:100242, Jun 2020. URL: https://doi.org/10.1016/j.bonr.2020.100242, doi:10.1016/j.bonr.2020.100242. This article has 14 citations and is from a peer-reviewed journal.
(chen2019tcirg1transgenicrescue pages 1-3): Weili Chen, Kirk Twaroski, Cindy Eide, Megan J. Riddle, Paul J. Orchard, and Jakub Tolar. Tcirg1 transgenic rescue of osteoclast function using induced pluripotent stem cells derived from patients with infantile malignant autosomal recessive osteopetrosis. The Journal of bone and joint surgery. American volume, 101:1939-1947, Nov 2019. URL: https://doi.org/10.2106/jbjs.19.00558, doi:10.2106/jbjs.19.00558. This article has 16 citations.
(penna2021autosomalrecessiveosteopetrosis pages 6-7): Sara Penna, Anna Villa, and Valentina Capo. Autosomal recessive osteopetrosis: mechanisms and treatments. Disease Models & Mechanisms, May 2021. URL: https://doi.org/10.1242/dmm.048940, doi:10.1242/dmm.048940. This article has 70 citations and is from a domain leading peer-reviewed journal.

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Pathophysiology

Pathograph

Phenotypes

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Treatments

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References & Deep Research

References

Deep Research

Disease Characteristics Research Template

Target Disease

Research Objectives

1. Disease Information

2. Etiology

3. Phenotypes

4. Genetic/Molecular Information

5. Environmental Information

6. Mechanism / Pathophysiology

7. Anatomical Structures Affected

8. Temporal Development

9. Inheritance and Population

10. Diagnostics

11. Outcome/Prognosis

12. Treatment

13. Prevention

14. Other Species / Natural Disease

15. Model Organisms

Citation Requirements

Output Format

Comprehensive Disease Characteristics Report: Autosomal Recessive Osteopetrosis Type 2 (ARO2; TCIRG1-related)

1. Disease information

1.1 Overview / definition

1.2 Key identifiers (with URLs / dates when available)

1.3 Synonyms / alternative names

1.4 Evidence origin (individual vs aggregated)

2. Etiology

2.1 Primary causal factors

2.2 Risk factors

2.3 Protective factors

2.4 Gene–environment interactions

3. Phenotypes (with suggested HPO terms)

3.1 Core phenotype spectrum (TCIRG1-related malignant/infantile ARO)

3.2 Phenotype frequencies from a 2023 TCIRG1 cohort (Egyptian families; n=16 affected)

3.3 Radiologic hallmark phenotypes (HPO) and supporting figure

3.4 Age of onset, severity, progression

3.5 Quality-of-life impact

4. Genetic / molecular information

4.1 Causal gene(s)

4.2 Pathogenic variant types and recent variant series

4.3 Functional consequence

4.4 Modifier genes / epigenetics / chromosomal abnormalities

5. Environmental information

6. Mechanism / pathophysiology

6.1 Core causal chain (upstream → downstream)

6.2 Cell types (CL terms suggestions)

6.3 Biological process and cellular component suggestions (GO)

6.4 Bone marrow niche mechanism (engraftment relevance)

6.5 Molecular profiling / multi-omics

7. Anatomical structures affected (UBERON suggestions)

7.1 Organ/system level

7.2 Tissue/cell level

7.3 Subcellular level (GO-CC suggestions)

8. Temporal development

8.1 Onset

8.2 Progression

8.3 Critical period

9. Inheritance and population

9.1 Inheritance

9.2 Epidemiology (statistics)

9.3 Population factors

10. Diagnostics

10.1 Clinical evaluation

10.2 Laboratory findings

10.3 Imaging

10.4 Pathology

10.5 Genetic testing

10.6 Differential diagnosis