Kosaki overgrowth syndrome (KOGS) is an extremely rare autosomal dominant disorder caused by heterozygous activating missense variants in PDGFRB. Clinical features include skeletal overgrowth, coarsening of facial features, enlargement of hands and feet, progressive scoliosis, and may include white matter abnormalities. Features typically begin to appear after age 6. The condition shares overlapping features with other PDGFRB gain-of-function disorders including Penttinen premature aging syndrome and infantile myofibromatosis, but is distinguished by prominent overgrowth and skeletal findings. Vascular complications including cerebral vasculopathy may arise with age.
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name: Kosaki_Overgrowth_Syndrome
creation_date: '2026-04-04T00:00:00Z'
updated_date: '2026-05-09T21:17:09Z'
category: Genetic
parents:
- Overgrowth Syndrome
- Skeletal Dysplasia
disease_term:
preferred_term: Kosaki overgrowth syndrome
term:
id: MONDO:0014704
label: skeletal overgrowth-craniofacial dysmorphism-hyperelastic skin-white matter lesions syndrome
description: >-
Kosaki overgrowth syndrome (KOGS) is an extremely rare autosomal dominant
disorder caused by heterozygous activating missense variants in PDGFRB.
Clinical features include skeletal overgrowth, coarsening of
facial features, enlargement of hands and feet, progressive scoliosis,
and may include white matter abnormalities. Features typically begin to appear after
age 6. The condition shares overlapping features with other PDGFRB
gain-of-function disorders including Penttinen premature aging syndrome
and infantile myofibromatosis, but is distinguished by prominent
overgrowth and skeletal findings. Vascular complications including
cerebral vasculopathy may arise with age.
prevalence:
- population: Global
percentage: Rare
notes: >-
Extremely rare; fewer than 25 cases reported worldwide.
inheritance:
- name: Autosomal dominant
inheritance_term:
preferred_term: Autosomal dominant inheritance
term:
id: HP:0000006
label: Autosomal dominant inheritance
genetic:
- name: PDGFRB Gain-of-Function Mutations
gene_term:
preferred_term: PDGFRB
term:
id: hgnc:8804
label: PDGFRB
association: Causative
features: >-
Heterozygous activating missense variants in PDGFRB cause constitutive receptor
activation. The germline P584R mutant identified in overgrowth syndrome is a
stronger oncogene than the germline R561C mutant associated with myofibromatosis,
and this difference in potency may explain the distinct overgrowth phenotype.
evidence:
- reference: PMID:26455322
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "the germline mutant identified in overgrowth syndrome, P584R, was a stronger oncogene than the germline R561C mutant associated with myofibromatosis."
explanation: Functional characterization shows P584R is a potent activating variant.
- reference: PMID:35221873
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Heterozygous activating missense variants of PDGFRB are associated with the phenotype of Kosaki overgrowth syndrome (KOGS)."
explanation: Confirms activating PDGFRB variants cause KOGS.
phenotypes:
- name: Overgrowth
category: Growth
frequency: VERY_FREQUENT
phenotype_term:
preferred_term: Overgrowth
term:
id: HP:0001548
label: Overgrowth
evidence:
- reference: PMID:35221873
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "enlargement of the hands/feet, and progressive scoliosis started to appear after an average age of 6."
explanation: Overgrowth is a defining feature of KOGS.
- name: Scoliosis
category: Musculoskeletal
frequency: FREQUENT
phenotype_term:
preferred_term: Scoliosis
term:
id: HP:0002650
label: Scoliosis
evidence:
- reference: PMID:35221873
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "enlargement of the hands/feet, and progressive scoliosis started to appear after an average age of 6."
explanation: Progressive scoliosis is a key feature of KOGS.
- name: Coarse Facial Features
category: Craniofacial
frequency: VERY_FREQUENT
phenotype_term:
preferred_term: Coarse facial features
term:
id: HP:0000280
label: Coarse facial features
evidence:
- reference: PMID:35221873
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The coarsening of the facial features, enlargement of the hands/feet, and progressive scoliosis started to appear after an average age of 6."
explanation: Coarsening of facial features is a defining feature of KOGS.
- name: Skeletal Dysplasia
category: Musculoskeletal
frequency: FREQUENT
phenotype_term:
preferred_term: Skeletal dysplasia
term:
id: HP:0002652
label: Skeletal dysplasia
evidence:
- reference: PMID:34738614
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "Autosomal dominant PDGFRβ gain-of-function mutations in mice and humans cause a spectrum of wasting and overgrowth disorders afflicting the skeleton and other connective tissues"
explanation: Skeletal manifestations are a core feature of PDGFRB gain-of-function disorders.
- name: Periventricular White Matter Signal Abnormalities
category: Neurologic
frequency: VERY_FREQUENT
phenotype_term:
preferred_term: Periventricular white matter signal abnormalities
term:
id: HP:0002500
label: Abnormal cerebral white matter morphology
evidence:
- reference: PMID:31710779
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
In addition to skeletal overgrowth, these patients exhibit hyperelastic,
translucent, and fragile skin, scoliosis, progressive loss of subcutaneous
adipose tissue, skull deformity, infantile myofibromas, neuropsychiatric
symptoms, and arachnoid cysts in the posterior fossa and periventricular
white matter signal abnormalities on neuroimaging.
explanation: >-
The 2019 KOGS review identifies periventricular white matter signal
abnormalities as part of the reported phenotype constellation.
- name: Posterior Fossa Arachnoid Cysts
category: Neurologic
frequency: FREQUENT
phenotype_term:
preferred_term: Posterior fossa arachnoid cysts
term:
id: HP:0100702
label: Arachnoid cyst
evidence:
- reference: PMID:31710779
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "arachnoid cysts in the posterior fossa and periventricular white matter signal abnormalities on neuroimaging."
explanation: >-
The 2019 KOGS review identifies posterior fossa arachnoid cysts as part
of the recurrent neuroimaging phenotype.
- name: Lipodystrophy
category: Connective Tissue
frequency: FREQUENT
phenotype_term:
preferred_term: Lipodystrophy
term:
id: HP:0009125
label: Lipodystrophy
evidence:
- reference: PMID:31710779
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
In addition to skeletal overgrowth, these patients exhibit hyperelastic,
translucent, and fragile skin, scoliosis, progressive loss of subcutaneous
adipose tissue, skull deformity, infantile myofibromas, neuropsychiatric
symptoms, and arachnoid cysts in the posterior fossa and periventricular
white matter signal abnormalities on neuroimaging.
explanation: >-
Progressive loss of subcutaneous adipose tissue supports lipodystrophy as
a recurrent KOGS feature.
- reference: DOI:10.1111/cge.13752
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The KOGS phenotype includes characteristic facial features, tall stature,
scoliosis, hyperelastic thin skin, lipodystrophy, variable intellectual
and neurological deterioration, and abnormalities on brain imaging.
explanation: >-
The 2020 phenotype-expansion series explicitly includes lipodystrophy in
the KOGS phenotype.
- name: Hyperelastic Fragile Skin
category: Integument
frequency: VERY_FREQUENT
phenotype_term:
preferred_term: Hyperelastic fragile skin
term:
id: HP:0000974
label: Hyperextensible skin
evidence:
- reference: PMID:31710779
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Presence of skeletal overgrowth, distinctive facial features,
characteristic hyperelastic and fragile skin, and cerebral white matter
lesions with neuropsychiatric symptoms should prompt genetic analysis of
the PDGFRB.
explanation: >-
Hyperelastic and fragile skin is named as part of the characteristic KOGS
diagnostic gestalt.
- reference: DOI:10.1111/cge.13752
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The KOGS phenotype includes characteristic facial features, tall stature,
scoliosis, hyperelastic thin skin, lipodystrophy, variable intellectual
and neurological deterioration, and abnormalities on brain imaging.
explanation: The 2020 case series supports hyperelastic thin skin as a KOGS phenotype.
- name: Cerebrovascular Artery Dilation and Aneurysm
category: Cardiovascular
frequency: OCCASIONAL
phenotype_term:
preferred_term: Cerebrovascular artery dilation and aneurysm
term:
id: HP:0004944
label: Dilatation of the cerebral artery
evidence:
- reference: DOI:10.1111/cge.13752
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Importantly, we report fusiform aneurysm of the basilar artery in two
patients.
explanation: >-
This phenotype-expansion series directly reports basilar artery fusiform
aneurysms in KOGS patients.
- reference: DOI:10.1002/ajmg.a.62027
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The analysis showed the progressive dilation of basilar and vertebral
arteries and coronary arteries commencing during the teenage years and
early 20s.
explanation: >-
Serial imaging of the original KOGS patients supports progressive
cerebral-artery dilation as part of the vascular phenotype.
pathophysiology:
- name: Constitutive PDGFRB Activation
description: >-
Activating PDGFRB mutations cause ligand-independent constitutive receptor
signaling.
genes:
- preferred_term: PDGFRB
term:
id: hgnc:8804
label: PDGFRB
molecular_functions:
- preferred_term: platelet-derived growth factor beta-receptor activity
term:
id: GO:0005019
label: platelet-derived growth factor beta-receptor activity
downstream:
- target: STAT5-IGF1 Axis Activation
description: Constitutive PDGFRB signaling activates the STAT5-IGF1 axis.
evidence:
- reference: PMID:26455322
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "the PDGFRB mutations previously identified in familial IM and overgrowth syndrome activate the receptor in the absence of ligand, supporting the hypothesis that these mutations cause the diseases."
explanation: Confirms constitutive PDGFRB activation underlies the disease.
- name: STAT5-IGF1 Axis Activation
description: >-
Mutant PDGFRβ causes increased STAT5 phosphorylation and overexpression of
IGF1, activating the STAT5-IGF1 axis locally in the skeleton.
downstream:
- target: Skeletal Overgrowth
description: STAT5-IGF1 signaling alters skeletal stem cell fate, promoting chondrogenesis.
evidence:
- reference: PMID:34738614
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "Increased STAT5 phosphorylation and overexpression of Igf1 and Socs2 in PDGFRβD849V cells suggests that overgrowth in mice involves PDGFRβD849V activating the STAT5-IGF1 axis locally in the skeleton."
explanation: Mouse model demonstrates the STAT5-IGF1 mechanism underlying skeletal overgrowth.
- name: Skeletal Overgrowth
description: >-
Skeletal stem cells from mutant mice show alterations in osteogenic and
chondrogenic precursors with promotion of chondrogenesis over osteogenesis,
leading to the overgrowth phenotype.
evidence:
- reference: PMID:34738614
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: "Autosomal dominant PDGFRβ gain-of-function mutations in mice and humans cause a spectrum of wasting and overgrowth disorders afflicting the skeleton and other connective tissues"
explanation: Establishes the skeletal overgrowth phenotype from PDGFRB gain-of-function.
treatments:
- name: Imatinib
description: >-
Tyrosine kinase inhibitor that targets constitutively activated PDGFRB.
Preclinical data and case reports support its use in PDGFRB gain-of-function
disorders.
treatment_term:
preferred_term: targeted therapy
term:
id: NCIT:C93352
label: Targeted Therapy
evidence:
- reference: PMID:26455322
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Importantly, all activated mutants were sensitive to tyrosine kinase inhibitors such as imatinib, nilotinib and ponatinib."
explanation: In vitro evidence of sensitivity to imatinib.
- reference: PMID:32500973
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Three patients were treated with imatinib and had robust and rapid response"
explanation: Clinical evidence of imatinib efficacy in PDGFRB spectrum disorders.
notes: >-
Macrocephaly is sometimes listed as a feature of KOGS in clinical descriptions,
but none of the available reference abstracts (PMID:35221873, PMID:26455322,
PMID:34738614, PMID:32500973) contain the term "macrocephaly". The phenotype
was removed pending a citable reference with an explicit quotable snippet.
references:
- reference: DOI:10.1002/ajmg.a.38310
title: Expansion of the phenotype of Kosaki overgrowth syndrome
found_in:
- Kosaki_Overgrowth_Syndrome-deep-research-falcon.md
findings:
- statement: Skeletal overgrowth is a characteristic of several genetic disorders that are linked to specific molecular signaling cascades.
supporting_text: Skeletal overgrowth is a characteristic of several genetic disorders that are linked to specific molecular signaling cascades.
evidence:
- reference: DOI:10.1002/ajmg.a.38310
reference_title: Expansion of the phenotype of Kosaki overgrowth syndrome
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Skeletal overgrowth is a characteristic of several genetic disorders that are linked to specific molecular signaling cascades.
explanation: Deep research cited this publication as relevant literature for Kosaki Overgrowth Syndrome.
- reference: DOI:10.1002/ajmg.a.61615
title: Activating variants in <scp><i>PDGFRB</i></scp> result in a spectrum of disorders responsive to imatinib monotherapy
found_in:
- Kosaki_Overgrowth_Syndrome-deep-research-falcon.md
findings:
- statement: Activating variants in <scp><i>PDGFRB</i></scp> result in a spectrum of disorders responsive to imatinib monotherapy
supporting_text: More than 50 individuals with activating variants in the receptor tyrosine kinase PDGFRB have been reported, separated based on clinical features into solitary myofibromas, infantile myofibromatosis, Penttinen syndrome with premature aging and osteopenia, Kosaki overgrowth syndrome, and fusiform aneurysms.
evidence:
- reference: DOI:10.1002/ajmg.a.61615
reference_title: Activating variants in <scp><i>PDGFRB</i></scp> result in a spectrum of disorders responsive to imatinib monotherapy
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: More than 50 individuals with activating variants in the receptor tyrosine kinase PDGFRB have been reported, separated based on clinical features into solitary myofibromas, infantile myofibromatosis, Penttinen syndrome with premature aging and osteopenia, Kosaki overgrowth syndrome, and fusiform aneurysms.
explanation: Deep research cited this publication as relevant literature for Kosaki Overgrowth Syndrome.
- reference: DOI:10.1002/ajmg.a.62027
title: Progressive cerebral and coronary aneurysms in the original two patients with Kosaki overgrowth syndrome
found_in:
- Kosaki_Overgrowth_Syndrome-deep-research-falcon.md
findings:
- statement: 'Skeletal overgrowth accompanied by de novo heterozygous activating mutations in PDGFRB (platelet‐derived growth factor receptor beta), that is, p.Pro584Arg and p.Trp566Arg, defines Kosaki overgrowth syndrome (OMIM #616592).'
supporting_text: 'Skeletal overgrowth accompanied by de novo heterozygous activating mutations in PDGFRB (platelet‐derived growth factor receptor beta), that is, p.Pro584Arg and p.Trp566Arg, defines Kosaki overgrowth syndrome (OMIM #616592).'
evidence:
- reference: DOI:10.1002/ajmg.a.62027
reference_title: Progressive cerebral and coronary aneurysms in the original two patients with Kosaki overgrowth syndrome
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: 'Skeletal overgrowth accompanied by de novo heterozygous activating mutations in PDGFRB (platelet‐derived growth factor receptor beta), that is, p.Pro584Arg and p.Trp566Arg, defines Kosaki overgrowth syndrome (OMIM #616592).'
explanation: Deep research cited this publication as relevant literature for Kosaki Overgrowth Syndrome.
- reference: DOI:10.1002/ajmg.a.62126
title: Segmental overgrowth and aneurysms due to mosaic <scp><i>PDGFRB</i></scp> p.(<scp>Tyr562Cys</scp>)
found_in:
- Kosaki_Overgrowth_Syndrome-deep-research-falcon.md
findings:
- statement: Activating variants in the platelet‐derived growth factor receptor β gene (PDGFRB) have been associated with Kosaki overgrowth syndrome, infantile myofibromatosis, and Penttinen premature aging syndrome.
supporting_text: Activating variants in the platelet‐derived growth factor receptor β gene (PDGFRB) have been associated with Kosaki overgrowth syndrome, infantile myofibromatosis, and Penttinen premature aging syndrome.
evidence:
- reference: DOI:10.1002/ajmg.a.62126
reference_title: Segmental overgrowth and aneurysms due to mosaic <scp><i>PDGFRB</i></scp> p.(<scp>Tyr562Cys</scp>)
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Activating variants in the platelet‐derived growth factor receptor β gene (PDGFRB) have been associated with Kosaki overgrowth syndrome, infantile myofibromatosis, and Penttinen premature aging syndrome.
explanation: Deep research cited this publication as relevant literature for Kosaki Overgrowth Syndrome.
- reference: DOI:10.1002/ajmg.c.31755
title: 'Kosaki overgrowth syndrome: A newly identified entity caused by pathogenic variants in platelet‐derived growth factor receptor‐beta'
found_in:
- Kosaki_Overgrowth_Syndrome-deep-research-falcon.md
findings:
- statement: 'Specific classes of de novo heterozygous gain‐of‐function pathogenic variants of the PDGFRB (platelet‐derived growth factor receptor‐beta) cause a distinctive overgrowth syndrome, named the Kosaki overgrowth syndrome (KOGS) (OMIM #616592).'
supporting_text: 'Specific classes of de novo heterozygous gain‐of‐function pathogenic variants of the PDGFRB (platelet‐derived growth factor receptor‐beta) cause a distinctive overgrowth syndrome, named the Kosaki overgrowth syndrome (KOGS) (OMIM #616592).'
evidence:
- reference: DOI:10.1002/ajmg.c.31755
reference_title: 'Kosaki overgrowth syndrome: A newly identified entity caused by pathogenic variants in platelet‐derived growth factor receptor‐beta'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: 'Specific classes of de novo heterozygous gain‐of‐function pathogenic variants of the PDGFRB (platelet‐derived growth factor receptor‐beta) cause a distinctive overgrowth syndrome, named the Kosaki overgrowth syndrome (KOGS) (OMIM #616592).'
explanation: Deep research cited this publication as relevant literature for Kosaki Overgrowth Syndrome.
- reference: DOI:10.1007/s00018-020-03753-y
title: PDGF receptor mutations in human diseases
found_in:
- Kosaki_Overgrowth_Syndrome-deep-research-falcon.md
findings:
- statement: PDGF receptor mutations in human diseases
supporting_text: PDGF receptor mutations in human diseases
- reference: DOI:10.1101/gad.300384.117
title: STAT1 modulates tissue wasting or overgrowth downstream from PDGFRβ
found_in:
- Kosaki_Overgrowth_Syndrome-deep-research-falcon.md
findings:
- statement: 'Platelet-derived growth factor (PDGF) acts through two conserved receptor tyrosine kinases: PDGFRα and PDGFRβ.'
supporting_text: 'Platelet-derived growth factor (PDGF) acts through two conserved receptor tyrosine kinases: PDGFRα and PDGFRβ.'
evidence:
- reference: DOI:10.1101/gad.300384.117
reference_title: STAT1 modulates tissue wasting or overgrowth downstream from PDGFRβ
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: 'Platelet-derived growth factor (PDGF) acts through two conserved receptor tyrosine kinases: PDGFRα and PDGFRβ.'
explanation: Deep research cited this publication as relevant literature for Kosaki Overgrowth Syndrome.
- reference: DOI:10.1111/cge.13192
title: Phenotype expansion and development in Kosaki overgrowth syndrome
found_in:
- Kosaki_Overgrowth_Syndrome-deep-research-falcon.md
findings:
- statement: We expand the Kosaki overgrowth syndrome (KOGS) phenotype by over 70% to include 24 unreported KOGS symptoms, in a first male patient, the third overall associated with the PDGFRB c.1751C>G p.(Pro584Arg) mutation.
supporting_text: We expand the Kosaki overgrowth syndrome (KOGS) phenotype by over 70% to include 24 unreported KOGS symptoms, in a first male patient, the third overall associated with the PDGFRB c.1751C>G p.(Pro584Arg) mutation.
evidence:
- reference: DOI:10.1111/cge.13192
reference_title: Phenotype expansion and development in Kosaki overgrowth syndrome
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: We expand the Kosaki overgrowth syndrome (KOGS) phenotype by over 70% to include 24 unreported KOGS symptoms, in a first male patient, the third overall associated with the PDGFRB c.1751C>G p.(Pro584Arg) mutation.
explanation: Deep research cited this publication as relevant literature for Kosaki Overgrowth Syndrome.
- reference: DOI:10.1111/cge.13752
title: 'Kosaki overgrowth syndrome: A novel pathogenic variant in <scp><i>PDGFRB</i></scp> and expansion of the phenotype including cerebrovascular complications'
found_in:
- Kosaki_Overgrowth_Syndrome-deep-research-falcon.md
findings:
- statement: Heterozygous activating variants in platelet‐derived growth factor, beta (PDGFRB) are associated with phenotypes including Kosaki overgrowth syndrome (KOGS), Penttinen syndrome and infantile myofibromatosis (IM).
supporting_text: Heterozygous activating variants in platelet‐derived growth factor, beta (PDGFRB) are associated with phenotypes including Kosaki overgrowth syndrome (KOGS), Penttinen syndrome and infantile myofibromatosis (IM).
evidence:
- reference: DOI:10.1111/cge.13752
reference_title: 'Kosaki overgrowth syndrome: A novel pathogenic variant in <scp><i>PDGFRB</i></scp> and expansion of the phenotype including cerebrovascular complications'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Heterozygous activating variants in platelet‐derived growth factor, beta (PDGFRB) are associated with phenotypes including Kosaki overgrowth syndrome (KOGS), Penttinen syndrome and infantile myofibromatosis (IM).
explanation: Deep research cited this publication as relevant literature for Kosaki Overgrowth Syndrome.
- reference: DOI:10.1159/000484532
title: A Clinical Review of Generalized Overgrowth Syndromes in the Era of Massively Parallel Sequencing
found_in:
- Kosaki_Overgrowth_Syndrome-deep-research-falcon.md
findings:
- statement: The overgrowth syndromes are important to diagnose, not just for accurate genetic counseling, but also for knowledge surrounding cancer surveillance and prognosis.
supporting_text: The overgrowth syndromes are important to diagnose, not just for accurate genetic counseling, but also for knowledge surrounding cancer surveillance and prognosis.
evidence:
- reference: DOI:10.1159/000484532
reference_title: A Clinical Review of Generalized Overgrowth Syndromes in the Era of Massively Parallel Sequencing
supports: SUPPORT
evidence_source: OTHER
snippet: The overgrowth syndromes are important to diagnose, not just for accurate genetic counseling, but also for knowledge surrounding cancer surveillance and prognosis.
explanation: Deep research cited this publication as relevant literature for Kosaki Overgrowth Syndrome.
- reference: DOI:10.3389/fgene.2024.1382371
title: 'Molecular mechanisms of human overgrowth and use of omics in its diagnostics: chances and challenges'
found_in:
- Kosaki_Overgrowth_Syndrome-deep-research-falcon.md
findings:
- statement: Overgrowth disorders comprise a group of entities with a variable phenotypic spectrum ranging from tall stature to isolated or lateralized overgrowth of body parts and or organs.
supporting_text: Overgrowth disorders comprise a group of entities with a variable phenotypic spectrum ranging from tall stature to isolated or lateralized overgrowth of body parts and or organs.
evidence:
- reference: DOI:10.3389/fgene.2024.1382371
reference_title: 'Molecular mechanisms of human overgrowth and use of omics in its diagnostics: chances and challenges'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Overgrowth disorders comprise a group of entities with a variable phenotypic spectrum ranging from tall stature to isolated or lateralized overgrowth of body parts and or organs.
explanation: Deep research cited this publication as relevant literature for Kosaki Overgrowth Syndrome.
| Disease name | Synonyms / alternate names | MONDO ID | OMIM disease ID | Causal gene (symbol; OMIM) | Notes on terminology | Sources |
|---|---|---|---|---|---|---|
| Kosaki overgrowth syndrome | KOGS; PDGFRB-related overgrowth syndrome; skeletal overgrowth-craniofacial dysmorphism-hyperelastic skin-white matter lesions syndrome | MONDO:0014704 | OMIM:616592 | PDGFRB; OMIM:173410 | Current disease label in case series/reviews is Kosaki overgrowth syndrome. Open Targets maps PDGFRB to the MONDO disease name skeletal overgrowth-craniofacial dysmorphism-hyperelastic skin-white matter lesions syndrome, which appears to represent the same entity in ontology-oriented resources. | (foster2020kosakiovergrowthsyndrome pages 1-2, minatogawa2017expansionofthe pages 1-2, gawlinski2018phenotypeexpansionand pages 1-4, OpenTargets Search: Kosaki overgrowth syndrome) |
| Skeletal overgrowth-craniofacial dysmorphism-hyperelastic skin-white matter lesions syndrome | Kosaki overgrowth syndrome; KOGS | MONDO:0014704 | OMIM:616592 | PDGFRB; OMIM:173410 | Descriptive/ontology-style synonym emphasizing the core phenotype: skeletal overgrowth, craniofacial dysmorphism, hyperelastic skin, and white matter lesions. Useful for cross-resource harmonization. | (OpenTargets Search: Kosaki overgrowth syndrome, takenouchi2019kosakiovergrowthsyndrome pages 1-3) |
| PDGFRB-related disorder spectrum entry relevant to KOGS | PDGFRB-activating variant spectrum (broader umbrella); overlaps with Penttinen syndrome and infantile myofibromatosis | Not disease-specific in cited sources | KOGS within OMIM:616592 | PDGFRB; OMIM:173410 | Several reviews argue that KOGS is part of a broader PDGFRB activating variant spectrum, but KOGS remains a clinically recognizable syndrome with its own OMIM entry. | (foster2020kosakiovergrowthsyndrome pages 1-2, takenouchi2021progressivecerebraland pages 4-5, wenger2020activatingvariantsin pages 2-4, wenger2020activatingvariantsin pages 14-15) |
Table: This table summarizes the main disease names, cross-resource identifiers, and terminology mappings used for Kosaki overgrowth syndrome. It is useful for harmonizing OMIM/MONDO naming with the PDGFRB-related disease spectrum in a knowledge base.
Kosaki overgrowth syndrome is an ultra-rare, clinically recognizable overgrowth/connective-tissue syndrome caused by heterozygous activating (gain-of-function) PDGFRB variants, classically presenting with postnatal skeletal overgrowth, hyperelastic/fragile skin with poor wound healing, lipodystrophy/progeroid features, scoliosis/joint contractures, and a characteristic neuroimaging pattern of periventricular white matter lesions and posterior fossa anomalies; an important recent expansion of the phenotype includes progressive, potentially fatal cerebrovascular and coronary aneurysms (foster2020kosakiovergrowthsyndrome pages 1-2, takenouchi2021progressivecerebraland pages 2-4, takenouchi2019kosakiovergrowthsyndrome pages 3-4).
Not found in the currently accessible full-text corpus: Orphanet ID, MeSH ID, ICD-10/ICD-11 codes.
The KOGS knowledge base is primarily derived from individual patients in case reports/case series and subsequent synthesis reviews (e.g., 2017 expansion; 2019 clinical review; 2020 case series with vascular complications; 2021 longitudinal imaging of original patients) (minatogawa2017expansionofthe pages 1-2, takenouchi2019kosakiovergrowthsyndrome pages 3-4, foster2020kosakiovergrowthsyndrome pages 1-2, takenouchi2021progressivecerebraland pages 2-4).
Primary cause: germline gain-of-function PDGFRB variants (typically missense) leading to constitutive receptor tyrosine kinase signaling (minatogawa2017expansionofthe pages 1-2, takenouchi2019kosakiovergrowthsyndrome pages 1-3, foster2020kosakiovergrowthsyndrome pages 10-11).
A mechanistic genotype contrast is explicitly described: “hypermorphic mutations in PDGFRB lead to Kosaki overgrowth syndrome… whereas hypomorphic mutations lead to idiopathic basal ganglia calcification” (minatogawa2017expansionofthe pages 1-2).
No environmental risk modifiers have been established in the accessible literature.
No protective factors or gene–environment interaction evidence specific to KOGS was identified in the accessible corpus.
| Phenotypic feature | Clinical category | Reported frequency / count | Phenotype details | Suggested HPO term(s) | Key source(s) |
|---|---|---|---|---|---|
| Periventricular white matter lesions / signal abnormalities | Neuroimaging abnormality | 100% (all reported patients in 2019 review) | Best detected on FLAIR; described as periventricular white matter hyperintensities/signal abnormalities and considered a core radiologic hallmark | HP:0002500 Cerebral white matter abnormality; HP:0007054 Periventricular white matter abnormalities | (takenouchi2019kosakiovergrowthsyndrome pages 3-4) |
| Posterior fossa arachnoid cysts / posterior fossa protrusion | Neuroimaging structural abnormality | ~83% (5/6) | Enlarged posterior fossa subarachnoid space/arachnoid cysts; part of recurrent CNS imaging pattern | HP:0002276 Arachnoid cyst; HP:0002280 Dandy-Walker malformation (when present) | (takenouchi2019kosakiovergrowthsyndrome pages 3-4, takenouchi2019kosakiovergrowthsyndrome pages 1-3) |
| Lipodystrophy / progressive loss of subcutaneous fat | Connective tissue / body composition | ~83% | Progressive periorbital and generalized subcutaneous fat loss contributes to prematurely aged/progeroid appearance | HP:0009125 Lipodystrophy; HP:0007495 Prematurely aged appearance | (foster2020kosakiovergrowthsyndrome pages 1-2, minatogawa2017expansionofthe pages 1-2, takenouchi2019kosakiovergrowthsyndrome pages 3-4) |
| Hyperelastic, thin, fragile, translucent skin with poor wound healing | Dermatologic / connective tissue | Common; described as universal in small review cohort for hyperelastic/thin/fragile skin | Includes velvety/translucent skin, widened scarring, skin hyperextensibility, poor wound healing | HP:0000974 Hyperelastic skin; HP:0008066 Thin skin; HP:0001030 Fragile skin; HP:0001058 Poor wound healing | (minatogawa2017expansionofthe pages 1-2, takenouchi2019kosakiovergrowthsyndrome pages 4-5, takenouchi2019kosakiovergrowthsyndrome pages 3-4) |
| Postnatal skeletal overgrowth / tall stature | Growth abnormality | Hallmark feature; frequency not numerically stated in accessible texts | Height >2 SD, large hands/feet or palms/soles; overgrowth is postnatal rather than clearly prenatal | HP:0000098 Tall stature; HP:0001161 Broad hand or HP:0100807 Large hand; HP:0001173 Broad foot or HP:0001833 Large foot | (foster2020kosakiovergrowthsyndrome pages 1-2, minatogawa2017expansionofthe pages 1-2, takenouchi2019kosakiovergrowthsyndrome pages 4-5, takenouchi2019kosakiovergrowthsyndrome pages 3-4) |
| Macrocephaly | Growth / craniofacial | Reported; frequency not available in accessible texts | May be pronounced from birth in some patients | HP:0000256 Macrocephaly | (gawlinski2018phenotypeexpansionand pages 1-4) |
| Craniosynostosis | Craniofacial / skeletal | ~33% | Can involve multiple sutures; cranial deformity and skull radiograph abnormalities reported | HP:0001363 Craniosynostosis | (foster2020kosakiovergrowthsyndrome pages 1-2, takenouchi2019kosakiovergrowthsyndrome pages 3-4, takenouchi2019kosakiovergrowthsyndrome pages 1-3) |
| Distinctive craniofacial dysmorphism | Craniofacial | Frequent, but no pooled % in accessible texts | Frontal prominence, supraorbital ridges, ptosis/proptosis, apparent hypertelorism, wide nasal bridge, high columella, triangular face, long palpebral fissures with lateral ectropion | HP:0002007 Frontal bossing; HP:0009912 Hypertelorism; HP:0000508 Ptosis; HP:0000589 Narrow palpebral fissure / HP:0000637 Long palpebral fissure; HP:0000601 Facial asymmetry not specific; HP:0000286 Epicanthus not established | (foster2020kosakiovergrowthsyndrome pages 1-2, gawlinski2018phenotypeexpansionand pages 1-4, takenouchi2019kosakiovergrowthsyndrome pages 3-4) |
| Scoliosis | Musculoskeletal | Reported in multiple patients; no pooled % in accessible texts | Often progressive; may occur with vertebral scalloping/widened spinal canal | HP:0002650 Scoliosis; HP:0000929 Abnormality of the vertebral column | (foster2020kosakiovergrowthsyndrome pages 1-2, minatogawa2017expansionofthe pages 1-2, gawlinski2018phenotypeexpansionand pages 1-4, takenouchi2019kosakiovergrowthsyndrome pages 3-4) |
| Joint contractures / camptodactyly / joint stiffness | Musculoskeletal | Reported; frequency not available | Progressive flexion contractures and camptodactyly broadened phenotype in later series | HP:0001371 Flexion contracture; HP:0004209 Camptodactyly; HP:0001387 Joint stiffness | (foster2020kosakiovergrowthsyndrome pages 1-2, gawlinski2018phenotypeexpansionand pages 1-4) |
| Intellectual disability / cognitive impairment | Neurodevelopmental | ~20% | Variable psychomotor and cognitive outcome; neurological deterioration is not universal | HP:0001249 Intellectual disability; HP:0001263 Global developmental delay | (foster2020kosakiovergrowthsyndrome pages 1-2, takenouchi2019kosakiovergrowthsyndrome pages 3-4, foster2020kosakiovergrowthsyndrome pages 8-9) |
| Neurological deterioration / white matter disease progression | Neurologic | Variable; no pooled % | Progressive neurologic decline reported in some individuals, often alongside white matter abnormalities | HP:0002344 Progressive neurologic deterioration; HP:0002500 Cerebral white matter abnormality | (foster2020kosakiovergrowthsyndrome pages 1-2, minatogawa2017expansionofthe pages 1-2) |
| Hydrocephalus / ventriculomegaly | Neuroimaging structural abnormality | Reported; frequency not available | Includes obstructive ventriculomegaly/hydrocephalus, sometimes requiring shunting; may co-occur with Dandy-Walker variant | HP:0000238 Hydrocephalus; HP:0002119 Ventriculomegaly | (foster2020kosakiovergrowthsyndrome pages 2-4, minatogawa2017expansionofthe pages 1-2, foster2020kosakiovergrowthsyndrome pages 8-9) |
| Dandy-Walker malformation / variant | Neuroimaging structural abnormality | Reported; frequency not available | Part of posterior fossa malformation spectrum in some patients | HP:0001305 Dandy-Walker malformation | (foster2020kosakiovergrowthsyndrome pages 2-4, minatogawa2017expansionofthe pages 1-2, maurer2025knowingandtreating pages 2-2) |
| Infantile myofibromatosis / myofibroma | Tumor-like mesenchymal manifestation | ~33% | Infantile-onset myofibromas are part of the PDGFRB-associated spectrum and occur in a subset of KOGS patients | HP:0100014 Myofibroma / infantile myofibromatosis-related term if curated locally | (takenouchi2019kosakiovergrowthsyndrome pages 3-4, takenouchi2019kosakiovergrowthsyndrome pages 1-3) |
| Cardiac abnormalities | Cardiovascular | At least 2/6 patients in 2019 review | Reported defects include dilated sinus of Valsalva, mitral valve bowing, mild pulmonic stenosis with post-stenotic dilatation, and coronary artery aneurysm | HP:0001644 Dilatation of the aorta; HP:0001634 Mitral valve prolapse/bowing-related term; HP:0001642 Pulmonic stenosis; HP:0031639 Coronary artery aneurysm | (takenouchi2019kosakiovergrowthsyndrome pages 3-4, takenouchi2019kosakiovergrowthsyndrome pages 4-5) |
| Cerebrovascular aneurysms / arterial dolichoectasia / tortuosity | Cardiovascular / neurovascular | Reported in multiple later cases; exact pooled prevalence not established | Basilar artery fusiform aneurysm, vertebrobasilar dolichoectasia, cervical/intracranial artery dysplasia and tortuosity; can cause stroke or fatal rupture | HP:0004942 Cerebral aneurysm; HP:0033650 Arterial tortuosity; HP:0100601 Dolichoectasia | (takenouchi2021progressivecerebraland pages 2-4, foster2020kosakiovergrowthsyndrome pages 1-2, foster2020kosakiovergrowthsyndrome pages 2-4, foster2020kosakiovergrowthsyndrome pages 8-9) |
| Stroke / thrombosis secondary to aneurysm | Neurovascular complication | Rare but severe; count not pooled | Ischaemic stroke from basilar artery aneurysm thrombosis and fatal rupture have been reported | HP:0001297 Stroke; HP:0004420 Arterial thrombosis | (foster2020kosakiovergrowthsyndrome pages 1-2, foster2020kosakiovergrowthsyndrome pages 2-4) |
| Prematurely aged / progeroid appearance | General / connective tissue | Progressive; frequency not pooled | Often linked to lipodystrophy and skin/connective-tissue changes; more apparent with age | HP:0007495 Prematurely aged appearance | (foster2020kosakiovergrowthsyndrome pages 1-2, maurer2025knowingandtreating pages 2-2, takenouchi2019kosakiovergrowthsyndrome pages 3-4) |
| Widely spaced teeth / delayed or abnormal dentition | Craniofacial / dental | Reported; frequency not available | Dental spacing and delayed eruption have been described in phenotype expansions | HP:0000687 Widely spaced teeth; HP:0000684 Delayed eruption of teeth | (foster2020kosakiovergrowthsyndrome pages 1-2, maurer2025knowingandtreating pages 2-2) |
| Carpal tunnel syndrome | Neuromuscular / peripheral nerve | Reported as novel association; frequency unknown | Pediatric CTS reported in at least one additional KOGS patient/family context | HP:0001382 Carpal tunnel syndrome | (foster2020kosakiovergrowthsyndrome pages 1-2) |
Table: This table summarizes the reported clinical and imaging features of Kosaki overgrowth syndrome, including approximate frequencies where available from small case series and reviews. It also suggests HPO mappings to support structured disease-knowledge-base annotation.
From Takenouchi et al. (2019) synthesis of the early cohort: - Periventricular white matter signal abnormalities: 100% (takenouchi2019kosakiovergrowthsyndrome pages 3-4) - Posterior fossa arachnoid cysts/anomalies: ~83% (takenouchi2019kosakiovergrowthsyndrome pages 3-4) - Lipodystrophy: ~83% (takenouchi2019kosakiovergrowthsyndrome pages 3-4) - Craniosynostosis: ~33% (takenouchi2019kosakiovergrowthsyndrome pages 3-4) - Intellectual disability (IQ < 70): ~20% (takenouchi2019kosakiovergrowthsyndrome pages 3-4) - Infantile myofibromatosis/myofibromas: ~33% (takenouchi2019kosakiovergrowthsyndrome pages 3-4, takenouchi2019kosakiovergrowthsyndrome pages 1-3) - Cardiac abnormalities: at least 2/6 early reported patients (takenouchi2019kosakiovergrowthsyndrome pages 3-4, takenouchi2019kosakiovergrowthsyndrome pages 4-5)
Cerebrovascular complications have become central to current understanding. Foster et al. report “fusiform aneurysm of the basilar artery” with severe outcomes including thrombosis/stroke and fatal rupture, concluding that “cerebrovascular complications are part of the phenotypic spectrum” and that “vascular imaging is indicated” (foster2020kosakiovergrowthsyndrome pages 1-2). Longitudinal follow-up of the original patients demonstrated progressive basilar/vertebral and coronary arterial dilation and aneurysm evolution beginning in adolescence/early adulthood (takenouchi2021progressivecerebraland pages 2-4).
In the broader PDGFRB activating-variant spectrum, imatinib therapy in one severe pediatric case was reported to improve multiple manifestations and “most importantly significant improvement in quality of life” (wenger2020activatingvariantsin pages 12-14). Although not exclusively KOGS, this informs real-world functional outcomes for PDGFRB-driven progressive connective-tissue disease.
Recurrent KOGS-associated variants described in multiple unrelated patients include: - PDGFRB c.1751C>G p.(Pro584Arg) (minatogawa2017expansionofthe pages 1-2, gawlinski2018phenotypeexpansionand pages 1-4, takenouchi2019kosakiovergrowthsyndrome pages 1-3) - PDGFRB c.1696T>C p.(Trp566Arg) (minatogawa2017expansionofthe pages 1-2, gawlinski2018phenotypeexpansionand pages 1-4, takenouchi2019kosakiovergrowthsyndrome pages 1-3)
A later case series added a novel de novo variant: - PDGFRB c.1477A>T p.(Ser493Cys) (foster2020kosakiovergrowthsyndrome pages 1-2, foster2020kosakiovergrowthsyndrome pages 2-4)
These are described as activating / gain-of-function and are interpreted as pathogenic/likely pathogenic in clinical genetics practice (minatogawa2017expansionofthe pages 1-2, foster2020kosakiovergrowthsyndrome pages 2-4).
KOGS is most often autosomal dominant due to de novo heterozygous variants in PDGFRB (minatogawa2017expansionofthe pages 1-2, gawlinski2018phenotypeexpansionand pages 1-4, foster2020kosakiovergrowthsyndrome pages 2-4). However, the broader PDGFRB activating-variant spectrum includes variable expressivity, adult-onset manifestations, and mosaic presentations (wenger2020activatingvariantsin pages 2-4, chenbhanich2021segmentalovergrowthand pages 1-2).
A key diagnostic lesson from mosaic PDGFRB vascular/overgrowth disease: blood exome may be negative; affected-tissue testing can reveal mosaic variants absent from blood (chenbhanich2021segmentalovergrowthand pages 1-2, chenbhanich2021segmentalovergrowthand pages 2-4).
No validated human modifier genes for KOGS were identified in the accessible corpus, but mechanistic work indicates STAT1 acts as a major genetic modifier of phenotypic direction (wasting vs overgrowth) in a PDGFRβ-activating mouse model (he2017stat1modulatestissue pages 8-9).
No non-genetic environmental, lifestyle, or infectious contributors have been established for KOGS in the accessible literature.
A 2024 overgrowth diagnostics review emphasizes that clinicians “should consider molecular genetic testing as a first diagnostic step in overgrowth syndromes” and highlights AI-assisted phenotype-driven approaches and deep sequencing for mosaicism detection (prawitt2024molecularmechanismsof pages 1-2, prawitt2024molecularmechanismsof pages 9-10). While not KOGS-specific, these methods are directly applicable to PDGFRB-related overgrowth, especially where mosaicism is suspected.
KOGS is described primarily as postnatal skeletal overgrowth (foster2020kosakiovergrowthsyndrome pages 1-2, takenouchi2019kosakiovergrowthsyndrome pages 3-4).
Multiple features are described as progressive, including progeroid appearance and vascular complications (foster2020kosakiovergrowthsyndrome pages 10-11). Serial imaging in original patients demonstrated progressive cerebrovascular and coronary artery dilation beginning in teenage years/early 20s (takenouchi2021progressivecerebraland pages 2-4).
No robust prevalence/incidence estimates were identified in the accessible corpus. Available evidence supports that KOGS is ultra-rare.
Penetrance cannot be reliably estimated due to the very small number of described individuals.
A key diagnostic gestalt is the constellation of skeletal overgrowth + characteristic skin/connective-tissue features + CNS white matter lesions/posterior fossa findings; Takenouchi et al. state that this phenotype “should prompt genetic analysis of the PDGFRB” (takenouchi2019kosakiovergrowthsyndrome pages 1-3).
Long-term outcome is incompletely defined due to rarity, but major morbidity and mortality contributors are increasingly recognized as progressive vascular aneurysms.
Evidence supports PDGFRB activating disorders as kinase-dependent and potentially responsive to TKIs: - Foster et al.: activating PDGFRB variants “are responsive to imatinib… suggesting that individuals with KOGS might also be candidates for treatment with tyrosine kinase inhibitors” (foster2020kosakiovergrowthsyndrome pages 10-11). - Wenger et al. report “robust and rapid” clinical responses to imatinib in several PDGFRB-activating cases; one severe case improved contractures and “significant improvement in quality of life” (wenger2020activatingvariantsin pages 12-14, wenger2020activatingvariantsin pages 2-4, wenger2020activatingvariantsin pages 14-15). - Mosaic PDGFRB p.Tyr562Cys aneurysm/overgrowth disease included sorafenib exposure, but aneurysm progression and rupture still occurred (chenbhanich2021segmentalovergrowthand pages 2-4).
Representative MAXO mappings are summarized in the management artifact.
| Domain | Recommendation / intervention | Details / evidence | Suggested MAXO term(s) | Citations |
|---|---|---|---|---|
| Genetic diagnostics | PDGFRB-focused testing when phenotype is suggestive | Characteristic combination of skeletal overgrowth, distinctive facial features, hyperelastic/fragile skin, and cerebral white matter lesions should prompt PDGFRB analysis; KOGS is caused by activating PDGFRB variants. | MAXO: genetic testing; MAXO: sequence analysis | (takenouchi2019kosakiovergrowthsyndrome pages 1-3, foster2020kosakiovergrowthsyndrome pages 1-2) |
| Genetic diagnostics | Whole-exome sequencing (WES) | WES was used diagnostically in reported KOGS cases and is recommended in overgrowth workups where phenotype overlaps multiple syndromes; useful for detecting heterozygous de novo PDGFRB variants. | MAXO: exome sequencing | (foster2020kosakiovergrowthsyndrome pages 2-4, kamien2018aclinicalreview pages 8-11, prawitt2024molecularmechanismsof pages 1-2) |
| Genetic diagnostics | Whole-genome sequencing (WGS) | WGS identified PDGFRB variants in KOGS cohorts; broader overgrowth reviews recommend molecular genetic testing early and support WGS when it improves diagnostic yield. | MAXO: genome sequencing | (foster2020kosakiovergrowthsyndrome pages 2-4, prawitt2024molecularmechanismsof pages 9-10, prawitt2024molecularmechanismsof pages 1-2) |
| Genetic diagnostics | Targeted multigene overgrowth panel | Custom NGS panels including overgrowth genes were successfully used in KOGS; panel/exome approaches are favored because differential diagnosis includes Sotos, Weaver, Beckwith-Wiedemann spectrum, Shprintzen-Goldberg, atypical EDS, Penttinen syndrome, and infantile myofibromatosis. | MAXO: multigene panel testing | (foster2020kosakiovergrowthsyndrome pages 2-4, kamien2018aclinicalreview pages 8-11, foster2020kosakiovergrowthsyndrome pages 10-11) |
| Genetic diagnostics | Sanger confirmation and parental testing | Reported variants were confirmed by bidirectional Sanger sequencing, with parental testing demonstrating de novo occurrence in multiple patients. | MAXO: confirmatory genetic testing | (foster2020kosakiovergrowthsyndrome pages 2-4, foster2020kosakiovergrowthsyndrome pages 1-2) |
| Mosaicism workup | Somatic testing of affected tissue when blood testing is negative | In mosaic PDGFRB disease, blood exome sequencing may be non-diagnostic; affected skin/biopsy tissue testing detected pathogenic variants absent from blood. This is relevant for segmental overgrowth/vascular phenotypes within the PDGFRB activating spectrum. | MAXO: biopsy-based molecular testing | (chenbhanich2021segmentalovergrowthand pages 1-2, chenbhanich2021segmentalovergrowthand pages 2-4) |
| Imaging at diagnosis | Brain MRI | Used to detect white matter lesions, ventriculomegaly/hydrocephalus, posterior fossa arachnoid cysts, Dandy-Walker malformation, and other structural brain abnormalities in KOGS. | MAXO: magnetic resonance imaging | (foster2020kosakiovergrowthsyndrome pages 2-4, takenouchi2019kosakiovergrowthsyndrome pages 3-4) |
| Imaging at diagnosis | Cerebral MR angiography / angioMRI | Recommended because cerebrovascular complications, including basilar artery fusiform aneurysms and dolichoectasia, are part of the KOGS spectrum. Suggested at diagnosis and again in adult life. | MAXO: magnetic resonance angiography | (foster2020kosakiovergrowthsyndrome pages 10-11) |
| Imaging surveillance | Serial neurovascular imaging | Repeat imaging is advised because aneurysms can be progressive and life-threatening; in mosaic/vascular PDGFRB disease, repeating imaging within 6–12 months after detection was considered reasonable. | MAXO: longitudinal imaging surveillance | (takenouchi2021progressivecerebraland pages 2-4, chenbhanich2021segmentalovergrowthand pages 1-2, wenger2020activatingvariantsin pages 14-15) |
| Cardiovascular evaluation | Echocardiography | Recommended for baseline vascular/cardiac screening; coronary aneurysms and other cardiac abnormalities have been reported in KOGS and broader PDGFRB activating variant spectrum. | MAXO: echocardiography | (foster2020kosakiovergrowthsyndrome pages 10-11, takenouchi2019kosakiovergrowthsyndrome pages 3-4, takenouchi2019kosakiovergrowthsyndrome pages 4-5) |
| Systemic vascular screening | Whole-body arterial tree imaging | Recommended after diagnosis in PDGFRB activating variant-related phenotypes to assess cervico-encephalic, coronary, and other arterial aneurysms/ectasia; MRA/CTA of brain, neck, chest, abdomen, and pelvis has been proposed. | MAXO: vascular imaging; MAXO: whole-body imaging | (chenbhanich2021segmentalovergrowthand pages 1-2, chenbhanich2021segmentalovergrowthand pages 2-4, wenger2020activatingvariantsin pages 14-15) |
| Risk reduction | Optimal blood pressure control | Suggested to reduce vascular wall tension and potentially slow progression of arterial dilation/aneurysms; specifically recommended once vascular risk in KOGS became apparent. | MAXO: blood pressure management; MAXO: antihypertensive therapy | (takenouchi2021progressivecerebraland pages 2-4, takenouchi2021progressivecerebraland pages 4-5) |
| Targeted therapy | Imatinib | Strongest therapeutic evidence in PDGFRB activating variant spectrum: rapid/robust responses reported in three children, including improvement in myofibromas and one severe progressive phenotype with improved joint contractures, coarse facial features, midfoot circumference, and quality of life. KOGS-specific literature suggests patients may be candidates for TKIs. | MAXO: tyrosine kinase inhibitor therapy; MAXO: imatinib administration | (wenger2020activatingvariantsin pages 12-14, wenger2020activatingvariantsin pages 2-4, wenger2020activatingvariantsin pages 14-15, foster2020kosakiovergrowthsyndrome pages 10-11) |
| Targeted therapy | Sunitinib / related TKIs | In vitro PDGFRB mutants were reported as sensitive to tyrosine kinase inhibitors including sunitinib; clinical-spectrum reviews cite experience with imatinib and sunitinib as supporting kinase-dependent disease, but direct KOGS-specific outcome data are limited. | MAXO: tyrosine kinase inhibitor therapy; MAXO: sunitinib administration | (wenger2020activatingvariantsin pages 12-14, wenger2020activatingvariantsin pages 14-15, wenger2020activatingvariantsin pages 16-16) |
| Targeted therapy | Sorafenib | Used in a patient with mosaic PDGFRB p.Tyr562Cys-associated overgrowth/aneurysms, but no clear clinical benefit was established and aneurysm progression/rupture still occurred; consortium reports also mention sorafenib exposure in PDGFRB-related disease. | MAXO: tyrosine kinase inhibitor therapy; MAXO: sorafenib administration | (chenbhanich2021segmentalovergrowthand pages 2-4, maurer2025knowingandtreating pages 2-2) |
| Treatment selection | Consider in vitro drug-sensitivity studies on patient fibroblasts | Emerging consortium recommendation: fibroblast testing may help determine which TKI most effectively blocks PDGFRB signaling for a given patient, especially because response appears variable. | MAXO: functional assay-guided treatment selection | (maurer2025knowingandtreating pages 2-2, maurer2025knowingandtreating pages 4-5) |
| Supportive monitoring | Assess treatment efficacy, safety, QoL, and symptom burden longitudinally | Observational study NCT05953857 is designed to track symptom burden, quality of life, TKI efficacy, and safety over long-term follow-up in KOGS/Penttinen syndrome due to activating PDGFRB variants. | MAXO: longitudinal clinical monitoring; MAXO: adverse event monitoring; MAXO: quality of life assessment | (NCT05953857 chunk 1, maurer2025knowingandtreating pages 5-6) |
| Clinical research | Enroll in observational registry / natural history study | IKKoPeS (NCT05953857) is a multicenter observational study for treated and untreated KOGS/Penttinen patients with activating PDGFRB variants; estimated enrollment 30, first posted 2023-07-20. | MAXO: clinical trial enrollment; MAXO: registry enrollment | (NCT05953857 chunk 1) |
Table: This table summarizes currently reported diagnostic strategies, vascular surveillance approaches, and targeted management options for Kosaki overgrowth syndrome and the broader PDGFRB activating variant spectrum. It highlights where evidence is strongest, especially for imaging surveillance and tyrosine kinase inhibitor use.
ClinicalTrials.gov NCT05953857 (“Knowing and Treating Kosaki/Penttinen Syndromes”, IKKoPeS) is a prospective observational study designed to follow treated and untreated patients with activating PDGFRB variants and to assess whether TKIs “could bring clinical benefit” (first posted 2023-07-20, estimated start 2023-10, estimated enrollment 30; estimated completion 2048-10) (NCT05953857 chunk 1). Primary/secondary outcomes include symptom burden and the proportion with QoL improvement or side effects under TKI (NCT05953857 chunk 1).
URL: https://clinicaltrials.gov/study/NCT05953857 (registry details summarized from record) (NCT05953857 chunk 1).
Primary prevention is not applicable for a de novo genetic disorder. However, secondary/tertiary prevention is clinically relevant: - Genetic counseling for recurrence risk (typically low for de novo, but consider parental mosaicism in principle). - Surveillance to prevent complications: early vascular screening and repeat imaging to detect aneurysms before rupture/thrombosis (foster2020kosakiovergrowthsyndrome pages 10-11, takenouchi2021progressivecerebraland pages 2-4).
No naturally occurring veterinary analogs of KOGS were identified in the accessible corpus.
A key mechanistic model is the Pdgfrb gain-of-function mouse (e.g., Pdgfrb D849V). STAT1 acts as a modifier that can shift phenotype between autoinflammatory wasting and progressive overgrowth, mapping conceptually onto the Penttinen vs Kosaki phenotypic axis and supporting PDGFRB hyperactivity as a driver mechanism (he2017stat1modulatestissue pages 8-9, he2017stat1modulatestissue pages 2-3).
References
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(wenger2020activatingvariantsin pages 14-15): Tara L. Wenger, Randall A. Bly, Natalie Wu, Catherine M. Albert, Julie Park, Joseph Shieh, Jirat Chenbhanich, Carrie L. Heike, Margaret P. Adam, Irene Chang, Angela Sun, Danny E. Miller, Anita E. Beck, Deepti Gupta, Markus D. Boos, Elaine H. Zackai, David Everman, Shireen Ganapathi, Meredith Wilson, John Christodoulou, Yuri A. Zarate, Cynthia Curry, Dong Li, Anne Guimier, Jeanne Amiel, Hakon Hakonarson, Richard Webster, Elizabeth J. Bhoj, Jonathan A. Perkins, John P. Dahl, and William B. Dobyns. Activating variants in pdgfrb result in a spectrum of disorders responsive to imatinib monotherapy. American Journal of Medical Genetics Part A, 182:1576-1591, Jun 2020. URL: https://doi.org/10.1002/ajmg.a.61615, doi:10.1002/ajmg.a.61615. This article has 37 citations.
(takenouchi2021progressivecerebraland pages 2-4): Toshiki Takenouchi, Kazuki Kodo, Fumito Yamazaki, Hirofumi Nakatomi, and Kenjiro Kosaki. Progressive cerebral and coronary aneurysms in the original two patients with kosaki overgrowth syndrome. American Journal of Medical Genetics Part A, 185:1003-999, Dec 2021. URL: https://doi.org/10.1002/ajmg.a.62027, doi:10.1002/ajmg.a.62027. This article has 6 citations.
(takenouchi2019kosakiovergrowthsyndrome pages 3-4): Toshiki Takenouchi, Hironobu Okuno, and Kenjiro Kosaki. Kosaki overgrowth syndrome: a newly identified entity caused by pathogenic variants in platelet‐derived growth factor receptor‐beta. American Journal of Medical Genetics Part C: Seminars in Medical Genetics, 181:650-657, Nov 2019. URL: https://doi.org/10.1002/ajmg.c.31755, doi:10.1002/ajmg.c.31755. This article has 19 citations.
(foster2020kosakiovergrowthsyndrome pages 10-11): Alison Foster, Basile Chalot, Thalia Antoniadi, Elise Schaefer, Rebecca Keelagher, Gavin Ryan, Quentin Thomas, Christophe Philippe, Ange‐Line Bruel, Arthur Sorlin, Christel Thauvin‐Robinet, Marc Bardou, Maxime Luu, Veronique Quenardelle, Valerie Wolff, Jessica Woodley, Pierre Vabres, Derek Lim, Rebecca Igbokwe, Annie Joseph, Harriet Walker, Andrea Jester, Jonathan Ellenbogen, Diana Johnson, Bethanie Rooke, Celia Moss, Trevor Cole, and Laurence Faivre. Kosaki overgrowth syndrome: a novel pathogenic variant in
(takenouchi2019kosakiovergrowthsyndrome pages 4-5): Toshiki Takenouchi, Hironobu Okuno, and Kenjiro Kosaki. Kosaki overgrowth syndrome: a newly identified entity caused by pathogenic variants in platelet‐derived growth factor receptor‐beta. American Journal of Medical Genetics Part C: Seminars in Medical Genetics, 181:650-657, Nov 2019. URL: https://doi.org/10.1002/ajmg.c.31755, doi:10.1002/ajmg.c.31755. This article has 19 citations.
(foster2020kosakiovergrowthsyndrome pages 8-9): Alison Foster, Basile Chalot, Thalia Antoniadi, Elise Schaefer, Rebecca Keelagher, Gavin Ryan, Quentin Thomas, Christophe Philippe, Ange‐Line Bruel, Arthur Sorlin, Christel Thauvin‐Robinet, Marc Bardou, Maxime Luu, Veronique Quenardelle, Valerie Wolff, Jessica Woodley, Pierre Vabres, Derek Lim, Rebecca Igbokwe, Annie Joseph, Harriet Walker, Andrea Jester, Jonathan Ellenbogen, Diana Johnson, Bethanie Rooke, Celia Moss, Trevor Cole, and Laurence Faivre. Kosaki overgrowth syndrome: a novel pathogenic variant in
(foster2020kosakiovergrowthsyndrome pages 2-4): Alison Foster, Basile Chalot, Thalia Antoniadi, Elise Schaefer, Rebecca Keelagher, Gavin Ryan, Quentin Thomas, Christophe Philippe, Ange‐Line Bruel, Arthur Sorlin, Christel Thauvin‐Robinet, Marc Bardou, Maxime Luu, Veronique Quenardelle, Valerie Wolff, Jessica Woodley, Pierre Vabres, Derek Lim, Rebecca Igbokwe, Annie Joseph, Harriet Walker, Andrea Jester, Jonathan Ellenbogen, Diana Johnson, Bethanie Rooke, Celia Moss, Trevor Cole, and Laurence Faivre. Kosaki overgrowth syndrome: a novel pathogenic variant in
(maurer2025knowingandtreating pages 2-2): A Maurer, L Mirakovska, A Foster, and K Kosaki. 'knowing and treating kosaki/penttinen syndrome'international collaborative consortium: recommendations for follow-up, natural history and a real-life observational …. Unknown journal, 2025.
(wenger2020activatingvariantsin pages 12-14): Tara L. Wenger, Randall A. Bly, Natalie Wu, Catherine M. Albert, Julie Park, Joseph Shieh, Jirat Chenbhanich, Carrie L. Heike, Margaret P. Adam, Irene Chang, Angela Sun, Danny E. Miller, Anita E. Beck, Deepti Gupta, Markus D. Boos, Elaine H. Zackai, David Everman, Shireen Ganapathi, Meredith Wilson, John Christodoulou, Yuri A. Zarate, Cynthia Curry, Dong Li, Anne Guimier, Jeanne Amiel, Hakon Hakonarson, Richard Webster, Elizabeth J. Bhoj, Jonathan A. Perkins, John P. Dahl, and William B. Dobyns. Activating variants in pdgfrb result in a spectrum of disorders responsive to imatinib monotherapy. American Journal of Medical Genetics Part A, 182:1576-1591, Jun 2020. URL: https://doi.org/10.1002/ajmg.a.61615, doi:10.1002/ajmg.a.61615. This article has 37 citations.
(chenbhanich2021segmentalovergrowthand pages 1-2): Jirat Chenbhanich, Yan Hu, Steven Hetts, Daniel Cooke, Christopher Dowd, Patrick Devine, Bianca Russell, Sung Hae L. Kang, Vivian Y. Chang, Adib A. Abla, Patricia Cornett, Iwei Yeh, Hane Lee, Julian A. Martinez‐Agosto, Ilona J. Frieden, and Joseph T. Shieh. Segmental overgrowth and aneurysms due to mosaic pdgfrb p.(tyr562cys). American Journal of Medical Genetics Part A, 185:1430-1436, Mar 2021. URL: https://doi.org/10.1002/ajmg.a.62126, doi:10.1002/ajmg.a.62126. This article has 16 citations.
(chenbhanich2021segmentalovergrowthand pages 2-4): Jirat Chenbhanich, Yan Hu, Steven Hetts, Daniel Cooke, Christopher Dowd, Patrick Devine, Bianca Russell, Sung Hae L. Kang, Vivian Y. Chang, Adib A. Abla, Patricia Cornett, Iwei Yeh, Hane Lee, Julian A. Martinez‐Agosto, Ilona J. Frieden, and Joseph T. Shieh. Segmental overgrowth and aneurysms due to mosaic pdgfrb p.(tyr562cys). American Journal of Medical Genetics Part A, 185:1430-1436, Mar 2021. URL: https://doi.org/10.1002/ajmg.a.62126, doi:10.1002/ajmg.a.62126. This article has 16 citations.
(he2017stat1modulatestissue pages 8-9): Chaoyong He, Shayna C. Medley, Jang Kim, Chengyi Sun, Hae Ryong Kwon, Hiromi Sakashita, Yair Pincu, Longbiao Yao, Danielle Eppard, Bojie Dai, William L. Berry, Timothy M. Griffin, and Lorin E. Olson. Stat1 modulates tissue wasting or overgrowth downstream from pdgfrβ. Genes & Development, 31:1666-1678, Aug 2017. URL: https://doi.org/10.1101/gad.300384.117, doi:10.1101/gad.300384.117. This article has 47 citations and is from a highest quality peer-reviewed journal.
(he2017stat1modulatestissue pages 2-3): Chaoyong He, Shayna C. Medley, Jang Kim, Chengyi Sun, Hae Ryong Kwon, Hiromi Sakashita, Yair Pincu, Longbiao Yao, Danielle Eppard, Bojie Dai, William L. Berry, Timothy M. Griffin, and Lorin E. Olson. Stat1 modulates tissue wasting or overgrowth downstream from pdgfrβ. Genes & Development, 31:1666-1678, Aug 2017. URL: https://doi.org/10.1101/gad.300384.117, doi:10.1101/gad.300384.117. This article has 47 citations and is from a highest quality peer-reviewed journal.
(guerit2021pdgfreceptormutations pages 6-8): Emilie Guérit, Florence Arts, Guillaume Dachy, Boutaina Boulouadnine, and Jean-Baptiste Demoulin. Pdgf receptor mutations in human diseases. Cellular and Molecular Life Sciences, 78:3867-3881, Jan 2021. URL: https://doi.org/10.1007/s00018-020-03753-y, doi:10.1007/s00018-020-03753-y. This article has 154 citations and is from a domain leading peer-reviewed journal.
(wenger2020activatingvariantsin pages 16-16): Tara L. Wenger, Randall A. Bly, Natalie Wu, Catherine M. Albert, Julie Park, Joseph Shieh, Jirat Chenbhanich, Carrie L. Heike, Margaret P. Adam, Irene Chang, Angela Sun, Danny E. Miller, Anita E. Beck, Deepti Gupta, Markus D. Boos, Elaine H. Zackai, David Everman, Shireen Ganapathi, Meredith Wilson, John Christodoulou, Yuri A. Zarate, Cynthia Curry, Dong Li, Anne Guimier, Jeanne Amiel, Hakon Hakonarson, Richard Webster, Elizabeth J. Bhoj, Jonathan A. Perkins, John P. Dahl, and William B. Dobyns. Activating variants in pdgfrb result in a spectrum of disorders responsive to imatinib monotherapy. American Journal of Medical Genetics Part A, 182:1576-1591, Jun 2020. URL: https://doi.org/10.1002/ajmg.a.61615, doi:10.1002/ajmg.a.61615. This article has 37 citations.
(guerit2021pdgfreceptormutations pages 8-9): Emilie Guérit, Florence Arts, Guillaume Dachy, Boutaina Boulouadnine, and Jean-Baptiste Demoulin. Pdgf receptor mutations in human diseases. Cellular and Molecular Life Sciences, 78:3867-3881, Jan 2021. URL: https://doi.org/10.1007/s00018-020-03753-y, doi:10.1007/s00018-020-03753-y. This article has 154 citations and is from a domain leading peer-reviewed journal.
(prawitt2024molecularmechanismsof pages 1-2): Dirk Prawitt and Thomas Eggermann. Molecular mechanisms of human overgrowth and use of omics in its diagnostics: chances and challenges. Frontiers in Genetics, Jun 2024. URL: https://doi.org/10.3389/fgene.2024.1382371, doi:10.3389/fgene.2024.1382371. This article has 5 citations and is from a peer-reviewed journal.
(prawitt2024molecularmechanismsof pages 9-10): Dirk Prawitt and Thomas Eggermann. Molecular mechanisms of human overgrowth and use of omics in its diagnostics: chances and challenges. Frontiers in Genetics, Jun 2024. URL: https://doi.org/10.3389/fgene.2024.1382371, doi:10.3389/fgene.2024.1382371. This article has 5 citations and is from a peer-reviewed journal.
(kamien2018aclinicalreview pages 8-11): Benjamin Kamien, Anne Ronan, Gemma Poke, Ingrid Sinnerbrink, Gareth Baynam, Michelle Ward, William T. Gibson, Tracy Dudding-Byth, and Rodney J. Scott. A clinical review of generalized overgrowth syndromes in the era of massively parallel sequencing. Molecular Syndromology, 9:70-82, Jan 2018. URL: https://doi.org/10.1159/000484532, doi:10.1159/000484532. This article has 56 citations and is from a peer-reviewed journal.
(maurer2025knowingandtreating pages 4-5): A Maurer, L Mirakovska, A Foster, and K Kosaki. 'knowing and treating kosaki/penttinen syndrome'international collaborative consortium: recommendations for follow-up, natural history and a real-life observational …. Unknown journal, 2025.
(NCT05953857 chunk 1): Knowing and Treating Kosaki/Penttinen Syndromes. Centre Hospitalier Universitaire Dijon. 2023. ClinicalTrials.gov Identifier: NCT05953857
(maurer2025knowingandtreating pages 5-6): A Maurer, L Mirakovska, A Foster, and K Kosaki. 'knowing and treating kosaki/penttinen syndrome'international collaborative consortium: recommendations for follow-up, natural history and a real-life observational …. Unknown journal, 2025.