👪

Inheritance

1

Autosomal dominant HP:0000006

Heterozygous FRYL loss-of-function variants cause the disorder. Thirteen of fourteen reported variants were confirmed de novo.

Autosomal dominant inheritance

Show evidence (2 references)

PMID:38479391 SUPPORT Human clinical

"the LoF variants in FRYL cause a dominant disorder with developmental and neurological symptoms due to haploinsufficiency"

The founding report concludes that FRYL loss-of-function variants act dominantly.

PMID:38479391 SUPPORT Human clinical

"The variants are confirmed de novo in all individuals except one."

Almost all variants arose de novo, consistent with a dominant disorder of reduced fitness.

?

Discussions and Knowledge Gaps

1

What does FRYL do in mammalian neurons and developing organs, and does it act through NDR kinases or NOTCH1 signaling?

KNOWLEDGE GAP OPEN fryl_molecular_mechanism_gap

Attached to

pathophysiology#FRYL Haploinsufficiency pathophysiology#Impaired Neuronal Development pathophysiology#Disrupted Organ Morphogenesis

The disease mechanism is established only to the level of gene dosage. Furry proteins activate or scaffold NDR kinases in yeast, worms and flies. In human epithelial and colorectal cancer cells FRYL binds Homer scaffolds and modulates YAP and Wnt/beta-catenin signaling downstream of the Crumbs polarity complex, and FRYL has also been reported to bind the active NOTCH1 intracellular domain. None of these routes has been tested for FRYL in a mammalian neurodevelopmental or organogenesis model.

Show evidence (4 references)

PMID:38479391 SUPPORT Other

"However, it is not known whether FRYL interacts with NDR kinases."

The founding paper states that the FRYL-NDR kinase link is untested.

PMID:20406475 SUPPORT Model organism

"We established that Fry and Trc could be co-immunoprecipitated from wing discs."

In flies, Furry physically associates with the NDR kinase Tricornered.

PMID:24403109 SUPPORT REVIEW SYNTHESIS Model organism

"Fry-NDR kinase signals are implicated in the control of polarized cell growth and morphogenesis in yeast, neurite outgrowth in nematode, and epidermal morphogenesis and dendritic tiling in fruit fly."

Review summarizing the conserved Furry-NDR kinase partnership across model organisms.

+ 1 more reference

⚙

Pathophysiology

3

FRYL Haploinsufficiency

Heterozygous truncating, frameshift and splice variants, and some missense variants, reduce FRYL function by half. FRYL is a 3,013-residue Furry-family protein whose molecular function in mammals is largely unknown.

FRYL hgnc:29127

Genetic context variant_origin: DE_NOVO zygosity: HETEROZYGOUS functional_impact_category: LOSS_OF_FUNCTION

Downstream

Impaired Neuronal Development

Disrupted Organ Morphogenesis

Low Body Weight

Show evidence (3 references)

PMID:38479391 SUPPORT Human clinical

"This is also supported by population genetic data from the gnomAD database that show that FRYL is intolerant to LoF (pLI = 1)."

Population constraint data support haploinsufficiency as the disease mechanism.

PMID:38479391 SUPPORT Human clinical

"Nine variants correspond to premature stop codons, frameshifts, or splicing variants."

Most disease variants are predicted to abolish the allele, consistent with loss of function.

PMID:38479391 SUPPORT Model organism

"One variant behaves as a severe LoF variant, whereas two others behave as partial LoF variants."

Knock-in of patient missense variants into the fly ortholog furry shows that these variants also reduce function.

Impaired Neuronal Development

The neurodevelopmental features are thought to reflect a requirement for FRYL in neuronal development. Direct evidence comes only from Drosophila: furry is expressed in neurons but not glia, is required for neuronal communication in the retina, and together with the NDR kinase Tricornered limits dendritic branching and enforces dendritic tiling. Whether FRYL acts through NDR kinases in human neurons is untested.

neuron CL:0000540

dendrite morphogenesis GO:0048813 ⚠ ABNORMAL

Downstream

Global Developmental Delay

Intellectual Disability

Delayed Speech and Language Development

Autism Spectrum Disorder

Behavioral Differences

Hypotonia

Seizures

Structural Brain Abnormalities

Show evidence (4 references)

PMID:38479391 SUPPORT INDIRECT Model organism

"We find that the fly FRYL ortholog, furry (fry), is expressed in multiple tissues, including the central nervous system where it is present in neurons but not in glia."

Neuronal expression of the fly ortholog places Furry-family function in neurons.

PMID:38479391 SUPPORT INDIRECT Model organism

"we showed that fry is required for fly development, wing hair morphogenesis, and neuronal communication in the retina"

Fly knock-in and loss-of-function alleles reduce retinal neuronal transmission, inferred to model the human neurological phenotype.

PMID:15479641 SUPPORT INDIRECT Model organism

"Dendrites of fry and trc mutants display excessive terminal branching and fail to avoid homologous dendritic branches, resulting in significant overlap of the dendritic fields."

Loss of fly furry disrupts dendrite morphogenesis, the best characterized neuronal function of the protein family.

+ 1 more reference

Disrupted Organ Morphogenesis

Congenital anomalies of the heart, left-right patterning, genitourinary tract, gastrointestinal tract, diaphragm, chest wall and face indicate that FRYL dosage matters for morphogenesis in several organ systems. Fryl-null mice die soon after birth with renal tubular defects, and morpholino knockdown of fryl in zebrafish causes cardiac and craniofacial defects. The developmental pathway through which FRYL acts in these tissues is unknown.

animal organ morphogenesis GO:0009887 ⚠ ABNORMAL

Downstream

Facial Dysmorphism

Congenital Heart Defects

Heterotaxy

Cryptorchidism

Hypospadias

Congenital Diaphragmatic Hernia

Jejunal Atresia

Microcolon

Sternal Anomalies

Vertebral Segmentation Defects

Horseshoe Kidney

Show evidence (3 references)

PMID:38479391 SUPPORT Human clinical

"Other features include neurobehavioral differences, autism spectrum disorder, hypotonia, and seizures, as well as congenital anomalies in cardiovascular, skeletal, gastrointestinal, renal, and urogenital systems."

The human cohort shows congenital anomalies across several organ systems.

PMID:29409347 SUPPORT INDIRECT Model organism

"Fryl protein is required for normal development and functional maintenance of kidney in mice."

Homozygous Fryl loss in mice disrupts kidney development, showing a mammalian requirement for Fryl in organogenesis.

PMID:38479391 SUPPORT INDIRECT BACKGROUND Model organism

"Morpholino-mediated knockdown of fryl in zebrafish causes cardiac and craniofacial defects during development."

The founding paper's introduction reports zebrafish knockdown data linking fryl to heart and craniofacial development.

⬡

Pathograph

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Phenotypes

21

Blood 1

Coagulopathy OCCASIONAL Abnormality of coagulation HP:0001928

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Two individuals were diagnosed with a coagulopathy of unknown etiology."

Two of fourteen individuals had a coagulopathy.

Cardiovascular 1

Congenital Heart Defects FREQUENT Abnormal heart morphology HP:0001627

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Congenital heart defects were also common within the cohort (7/14, 50%)."

Gives the cohort frequency of congenital heart defects.

Digestive 2

Jejunal Atresia OCCASIONAL HP:0005235

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Gastrointestinal anomalies were seen in three individuals (21%). They include midline livers in the setting of heterotaxy syndrome, jejunal atresia, microcolon, and right-sided stomach."

Jejunal atresia is one of the gastrointestinal anomalies reported in the cohort.

Microcolon OCCASIONAL HP:0004388

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Gastrointestinal anomalies were seen in three individuals (21%). They include midline livers in the setting of heterotaxy syndrome, jejunal atresia, microcolon, and right-sided stomach."

Microcolon is one of the gastrointestinal anomalies reported in the cohort.

Genitourinary 3

Cryptorchidism OCCASIONAL HP:0000028

Show evidence (2 references)

PMID:38479391 SUPPORT Human clinical

"Genitourinary abnormalities were reported in six individuals (6/14, 43%) and included undescended testes in three individuals, hypospadias in two individuals"

Three individuals had undescended testes.

PMID:40864423 SUPPORT Human clinical

"Physical examination of the newborn was notable for left enophthalmia, retrognathia, left upper extremity mesomelia with radial deviation of the left hand and absent left thumb, scoliosis, and hypospadias with cryptorchidism."

The newborn with a FRYL frameshift variant also had cryptorchidism.

Hypospadias OCCASIONAL HP:0000047

Show evidence (2 references)

PMID:38479391 SUPPORT Human clinical

"Genitourinary abnormalities were reported in six individuals (6/14, 43%) and included undescended testes in three individuals, hypospadias in two individuals"

Two individuals had hypospadias.

PMID:40864423 SUPPORT Human clinical

"Physical examination of the newborn was notable for left enophthalmia, retrognathia, left upper extremity mesomelia with radial deviation of the left hand and absent left thumb, scoliosis, and hypospadias with cryptorchidism."

The newborn with a FRYL frameshift variant had hypospadias.

Horseshoe Kidney OCCASIONAL HP:0000085

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"In the cohort reported here, a renal abnormality was reported in one individual (horseshoe kidney in individual 5)"

One of fourteen individuals had a horseshoe kidney.

Head and Neck 1

Facial Dysmorphism FREQUENT Abnormal facial shape HP:0001999

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Dysmorphic facial features were observed in a majority of individuals (11/14, 79%)"

Gives the cohort frequency of facial dysmorphism.

Musculoskeletal 4

Hypotonia FREQUENT HP:0001252

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Five of the probands were noted to have hypotonia, and an additional three were noted to have a confirmed history of seizures."

Five of thirteen probands had hypotonia.

Congenital Diaphragmatic Hernia HP:0000776

Show evidence (1 reference)

PMID:40864423 SUPPORT Human clinical

"Ultrasound findings were consistent with prior phenotypic descriptions; however, the fetus also had congenital diaphragmatic hernia (CDH)."

Case report extending the phenotype to congenital diaphragmatic hernia.

Sternal Anomalies OCCASIONAL Abnormal sternum morphology HP:0000766

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Skeletal abnormalities of the chest were noted in two individuals: one with non-union of the sternum and the other with pectus carinatum."

Two of fourteen individuals had sternal anomalies.

Vertebral Segmentation Defects HP:0003422

Show evidence (1 reference)

PMID:40864423 SUPPORT Human clinical

"Supine x-ray of neonate with left rib dysplasia, multiple segmentation abnormalities of vertebrae, and hypoplastic left radius with absent left thumb."

Radiographs of the newborn with a FRYL frameshift variant show vertebral segmentation defects and other skeletal anomalies.

Nervous System 7

Global Developmental Delay VERY_FREQUENT HP:0001263

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Neurodevelopmental issues, including DD and/or intellectual disability, were observed in all 13 individuals in the cohort."

Developmental delay or intellectual disability was universal in the assessable cohort.

Intellectual Disability FREQUENT HP:0001249

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Intellectual disability is also observed in 8/13 individuals in the studied cohort."

Gives the cohort frequency of intellectual disability.

Delayed Speech and Language Development VERY_FREQUENT HP:0000750

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"A total of 10 individuals were noted to have delayed development of speech and language, and one other individual was non-verbal at 8 years of age (11/13, 85%)."

Speech and language delay affected most of the cohort.

Autism Spectrum Disorder FREQUENT HP:0000717

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Autism spectrum disorder was observed in five individuals among those who were over the age of 3 and old enough to be diagnosed (5/12, 42%)."

Gives the cohort frequency of autism spectrum disorder.

Behavioral Differences FREQUENT Atypical behavior HP:0000708

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Other behavioral challenges were reported in nine individuals (9/13, 69%), including attention deficit hyperactivity disorder (ADHD) in two individuals and general behavioral disturbances in two individuals"

Gives the cohort frequency of behavioral differences.

Seizures OCCASIONAL HP:0001250

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"Five of the probands were noted to have hypotonia, and an additional three were noted to have a confirmed history of seizures."

Three probands had a confirmed history of seizures.

Structural Brain Abnormalities FREQUENT Abnormal brain morphology HP:0012443

Show evidence (2 references)

PMID:38479391 SUPPORT Human clinical

"Among the six individuals who had neuroimaging (brain magnetic resonance imaging [MRI] or computed tomography [CT]), two had abnormal structural results."

Two of six imaged patients had abnormal brain structure.

PMID:38479391 SUPPORT Human clinical

"Individual 9 had mild thinning of the corpus callosum with mild diffuse cerebral volume loss, and individual 11 had cortical dysplasia."

Names the two structural findings.

Growth 2

Heterotaxy OCCASIONAL HP:0030853

Show evidence (1 reference)

PMID:38479391 SUPPORT Human clinical

"There were two cases of heterotaxy syndrome."

Two of fourteen individuals had heterotaxy.

Low Body Weight FREQUENT Decreased body weight HP:0004325

Show evidence (2 references)

PMID:38479391 SUPPORT Human clinical

"four individuals (4/13, 31%) had a low weight"

Gives the cohort frequency of low weight at the most recent visit.

PMID:29409347 SUPPORT INDIRECT Model organism

"Rare Fryl-/- survivors showed growth retardation with significantly lower body weight compared to their littermate controls."

Complete Fryl loss in mice reduces body weight, supporting a growth role for the gene; human support is the cohort item above.

🧬

Genetic Associations

1

FRYL (Causative)

Gene: FRYL hgnc:29127 relationship_type: CAUSATIVE variant_origin: DE_NOVO

Show evidence (2 references)

PMID:38479391 SUPPORT Human clinical

"Here, we report fourteen individuals with heterozygous variants in FRYL who present with developmental delay, intellectual disability, dysmorphic features, and other congenital anomalies in multiple systems."

Founding cohort establishing FRYL as the causal gene.

PMID:40864423 SUPPORT Human clinical

"Exome sequencing identified a heterozygous pathogenic frame-shift variant in the FRYL (Fry-like transcription coactivator) gene"

An independent prenatal case carries a heterozygous FRYL frameshift variant.

🔬

Diagnosis

1

FRYL molecular genetic testing

The disorder has no clinical diagnostic criteria and is diagnosed by finding a heterozygous FRYL variant on exome sequencing, with parental testing to establish de novo status. One case was found prenatally by exome sequencing on amniocentesis.

exome sequencing NCIT:C101295

Show evidence (2 references)

PMID:38479391 SUPPORT Human clinical

"Trio sequencing was included in the analysis to identify de novo variants"

Patients in the founding cohort were diagnosed by trio exome sequencing.

PMID:40864423 SUPPORT Human clinical

"We report on a fetus with multiple congenital anomalies on prenatal ultrasound whose exome sequencing with amniocentesis revealed a heterozygous pathogenic variant in the FRYL gene."

Prenatal exome sequencing identified the disorder in a fetus.

{ }

Source YAML

click to show

name: Pan-Chung-Bellen Syndrome
creation_date: "2026-10-22T20:30:00Z"
category: Mendelian
synonyms:
- FRYL-related neurodevelopmental disorder with multiple anomalies
description: >-
  Pan-Chung-Bellen syndrome is an autosomal dominant neurodevelopmental
  disorder with multiple congenital anomalies caused by heterozygous, mostly de
  novo, loss-of-function variants in FRYL, a large Furry-family protein. The
  founding cohort of fourteen individuals showed developmental delay or
  intellectual disability in every assessable individual, frequent speech
  delay, behavioral differences, autism spectrum disorder, hypotonia and
  seizures, together with dysmorphic facial features and congenital anomalies
  of the heart (including heterotaxy), genitourinary tract, gastrointestinal
  tract and skeleton. Truncating variants, gnomAD loss-of-function intolerance,
  and Drosophila knock-in modelling of the missense variants point to FRYL
  haploinsufficiency. How reduced FRYL dosage disturbs neuronal and organ
  development in mammals is not known; the fly ortholog furry acts with the NDR
  kinase Tricornered in dendrite morphogenesis, and in human epithelial cells
  FRYL modulates YAP and Wnt signaling with Homer scaffolds, but neither route
  has been tested in neurons or developing organs.
disease_term:
  preferred_term: Pan-Chung-Bellen syndrome
  term:
    id: MONDO:0975953
    label: Pan-Chung-Bellen syndrome
parents:
- Neurodevelopmental Disorder
- Multiple Congenital Anomalies Syndrome
notes: >-
  MONDO:0975953 cross-references OMIM:621049 and records FRYL as its causal
  gene. MONDO records no descendants, so the entry is curated as one disease
  without subtypes. The synonym "FRYL-related neurodevelopmental disorder with
  multiple anomalies" is the former name given in PMID:40864423. A 2026 case
  report of a child with a FRYL variant and a co-occurring SUPT16H variant
  (PMID:42430062) has no PubMed abstract and is not cited. No GeneReviews
  chapter covers the disease.
inheritance:
- name: Autosomal dominant
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    Heterozygous FRYL loss-of-function variants cause the disorder. Thirteen of
    fourteen reported variants were confirmed de novo.
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the LoF variants in FRYL cause a dominant disorder with developmental and neurological symptoms due to haploinsufficiency"
    explanation: The founding report concludes that FRYL loss-of-function variants act dominantly.
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The variants are confirmed de novo in all individuals except one."
    explanation: Almost all variants arose de novo, consistent with a dominant disorder of reduced fitness.
pathophysiology:
- name: FRYL Haploinsufficiency
  description: >-
    Heterozygous truncating, frameshift and splice variants, and some missense
    variants, reduce FRYL function by half. FRYL is a 3,013-residue Furry-family
    protein whose molecular function in mammals is largely unknown.
  biological_scale: MOLECULAR
  genes:
  - preferred_term: FRYL
    term:
      id: hgnc:29127
      label: FRYL
  genetic_context:
    variant_origin: DE_NOVO
    zygosity: HETEROZYGOUS
    functional_impact_category: LOSS_OF_FUNCTION
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This is also supported by population genetic data from the gnomAD database that show that FRYL is intolerant to LoF (pLI = 1)."
    explanation: Population constraint data support haploinsufficiency as the disease mechanism.
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Nine variants correspond to premature stop codons, frameshifts, or splicing variants."
    explanation: Most disease variants are predicted to abolish the allele, consistent with loss of function.
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "One variant behaves as a severe LoF variant, whereas two others behave as partial LoF variants."
    explanation: Knock-in of patient missense variants into the fly ortholog furry shows that these variants also reduce function.
  downstream:
  - target: Impaired Neuronal Development
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Disrupted Organ Morphogenesis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Low Body Weight
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Impaired Neuronal Development
  description: >-
    The neurodevelopmental features are thought to reflect a requirement for
    FRYL in neuronal development. Direct evidence comes only from Drosophila:
    furry is expressed in neurons but not glia, is required for neuronal
    communication in the retina, and together with the NDR kinase Tricornered
    limits dendritic branching and enforces dendritic tiling. Whether FRYL acts
    through NDR kinases in human neurons is untested.
  biological_scale: CELLULAR
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: dendrite morphogenesis
    term:
      id: GO:0048813
      label: dendrite morphogenesis
    modifier: ABNORMAL
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: "We find that the fly FRYL ortholog, furry (fry), is expressed in multiple tissues, including the central nervous system where it is present in neurons but not in glia."
    explanation: Neuronal expression of the fly ortholog places Furry-family function in neurons.
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: "we showed that fry is required for fly development, wing hair morphogenesis, and neuronal communication in the retina"
    explanation: Fly knock-in and loss-of-function alleles reduce retinal neuronal transmission, inferred to model the human neurological phenotype.
  - reference: PMID:15479641
    reference_title: Control of dendritic branching and tiling by the Tricornered-kinase/Furry signaling pathway in Drosophila sensory neurons.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: "Dendrites of fry and trc mutants display excessive terminal branching and fail to avoid homologous dendritic branches, resulting in significant overlap of the dendritic fields."
    explanation: Loss of fly furry disrupts dendrite morphogenesis, the best characterized neuronal function of the protein family.
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individual 9 had mild thinning of the corpus callosum with mild diffuse cerebral volume loss, and individual 11 had cortical dysplasia."
    explanation: Structural brain abnormalities in two of six imaged patients are the human readout of disturbed brain development; they do not show which cellular process is affected.
  downstream:
  - target: Global Developmental Delay
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Intellectual Disability
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Delayed Speech and Language Development
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Autism Spectrum Disorder
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Behavioral Differences
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Hypotonia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Seizures
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Structural Brain Abnormalities
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Disrupted Organ Morphogenesis
  description: >-
    Congenital anomalies of the heart, left-right patterning, genitourinary
    tract, gastrointestinal tract, diaphragm, chest wall and face indicate that
    FRYL dosage matters for morphogenesis in several organ systems. Fryl-null
    mice die soon after birth with renal tubular defects, and morpholino
    knockdown of fryl in zebrafish causes cardiac and craniofacial defects. The
    developmental pathway through which FRYL acts in these tissues is unknown.
  biological_scale: TISSUE
  biological_processes:
  - preferred_term: animal organ morphogenesis
    term:
      id: GO:0009887
      label: animal organ morphogenesis
    modifier: ABNORMAL
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Other features include neurobehavioral differences, autism spectrum disorder, hypotonia, and seizures, as well as congenital anomalies in cardiovascular, skeletal, gastrointestinal, renal, and urogenital systems."
    explanation: The human cohort shows congenital anomalies across several organ systems.
  - reference: PMID:29409347
    reference_title: Fryl deficiency is associated with defective kidney development and function in mice.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: "Fryl protein is required for normal development and functional maintenance of kidney in mice."
    explanation: Homozygous Fryl loss in mice disrupts kidney development, showing a mammalian requirement for Fryl in organogenesis.
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    directness: INDIRECT
    quote_role: BACKGROUND
    evidence_source: MODEL_ORGANISM
    snippet: "Morpholino-mediated knockdown of fryl in zebrafish causes cardiac and craniofacial defects during development."
    explanation: The founding paper's introduction reports zebrafish knockdown data linking fryl to heart and craniofacial development.
  downstream:
  - target: Facial Dysmorphism
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Congenital Heart Defects
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Heterotaxy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Cryptorchidism
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Hypospadias
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Congenital Diaphragmatic Hernia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Jejunal Atresia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Microcolon
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Sternal Anomalies
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Vertebral Segmentation Defects
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Horseshoe Kidney
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
phenotypes:
- category: Neurological
  name: Global Developmental Delay
  description: >-
    Developmental delay and/or intellectual disability was present in all 13
    individuals old enough to assess.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Neurodevelopmental issues, including DD and/or intellectual disability, were observed in all 13 individuals in the cohort."
    explanation: Developmental delay or intellectual disability was universal in the assessable cohort.
- category: Neurological
  name: Intellectual Disability
  description: >-
    Intellectual disability was reported in 8 of 13 individuals; the remainder
    had developmental delay.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Intellectual disability is also observed in 8/13 individuals in the studied cohort."
    explanation: Gives the cohort frequency of intellectual disability.
- category: Neurological
  name: Delayed Speech and Language Development
  description: >-
    Ten individuals had delayed speech and language and one was non-verbal at 8
    years (11 of 13).
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Delayed speech and language development
    term:
      id: HP:0000750
      label: Delayed speech and language development
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A total of 10 individuals were noted to have delayed development of speech and language, and one other individual was non-verbal at 8 years of age (11/13, 85%)."
    explanation: Speech and language delay affected most of the cohort.
- category: Behavioral
  name: Autism Spectrum Disorder
  description: Autism spectrum disorder was diagnosed in 5 of 12 individuals old enough to assess.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Autism spectrum disorder
    term:
      id: HP:0000717
      label: Autism
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autism spectrum disorder was observed in five individuals among those who were over the age of 3 and old enough to be diagnosed (5/12, 42%)."
    explanation: Gives the cohort frequency of autism spectrum disorder.
- category: Behavioral
  name: Behavioral Differences
  description: >-
    Behavioral challenges other than autism were reported in 9 of 13
    individuals, including ADHD, anxiety, tics, depressive and eating disorders.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Behavioral differences
    term:
      id: HP:0000708
      label: Atypical behavior
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Other behavioral challenges were reported in nine individuals (9/13, 69%), including attention deficit hyperactivity disorder (ADHD) in two individuals and general behavioral disturbances in two individuals"
    explanation: Gives the cohort frequency of behavioral differences.
- category: Neurological
  name: Hypotonia
  description: Hypotonia was noted in five individuals.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Five of the probands were noted to have hypotonia, and an additional three were noted to have a confirmed history of seizures."
    explanation: Five of thirteen probands had hypotonia.
- category: Neurological
  name: Seizures
  description: >-
    Three individuals had confirmed seizures, including generalized epilepsy and
    focal seizures; one further individual had possible seizure-like staring
    spells.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Seizures
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Five of the probands were noted to have hypotonia, and an additional three were noted to have a confirmed history of seizures."
    explanation: Three probands had a confirmed history of seizures.
- category: Craniofacial
  name: Facial Dysmorphism
  description: >-
    Dysmorphic facial features were seen in 11 of 14 individuals, without a
    single recognizable gestalt: upslanting or downslanting palpebral fissures,
    deep-set eyes, epicanthal folds, flat nasal bridge, frontal bossing and ear
    anomalies.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Facial dysmorphism
    term:
      id: HP:0001999
      label: Abnormal facial shape
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dysmorphic facial features were observed in a majority of individuals (11/14, 79%)"
    explanation: Gives the cohort frequency of facial dysmorphism.
- category: Cardiovascular
  name: Congenital Heart Defects
  description: >-
    Congenital heart defects were present in half the cohort and were often
    complex, requiring surgery; one individual with hypoplastic left heart
    syndrome died at 4 months. A fetus with a FRYL frameshift variant had aortic
    arch hypoplasia.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Congenital heart defect
    term:
      id: HP:0001627
      label: Abnormal heart morphology
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Congenital heart defects were also common within the cohort (7/14, 50%)."
    explanation: Gives the cohort frequency of congenital heart defects.
- category: Cardiovascular
  name: Heterotaxy
  description: >-
    Two individuals had heterotaxy with a midline liver; one had a right-sided
    spleen and the other a right-sided stomach.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Heterotaxy
    term:
      id: HP:0030853
      label: Heterotaxy
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "There were two cases of heterotaxy syndrome."
    explanation: Two of fourteen individuals had heterotaxy.
- category: Genitourinary
  name: Cryptorchidism
  description: Undescended testes were reported in three individuals in the founding cohort and in one newborn.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Cryptorchidism
    term:
      id: HP:0000028
      label: Cryptorchidism
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Genitourinary abnormalities were reported in six individuals (6/14, 43%) and included undescended testes in three individuals, hypospadias in two individuals"
    explanation: Three individuals had undescended testes.
  - reference: PMID:40864423
    reference_title: Novel Fetal Phenotype for Pan-Chung-Bellen Syndrome Including Congenital Diaphragmatic Hernia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Physical examination of the newborn was notable for left enophthalmia, retrognathia, left upper extremity mesomelia with radial deviation of the left hand and absent left thumb, scoliosis, and hypospadias with cryptorchidism."
    explanation: The newborn with a FRYL frameshift variant also had cryptorchidism.
- category: Genitourinary
  name: Hypospadias
  description: Hypospadias was reported in two individuals in the founding cohort and in one newborn.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Hypospadias
    term:
      id: HP:0000047
      label: Hypospadias
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Genitourinary abnormalities were reported in six individuals (6/14, 43%) and included undescended testes in three individuals, hypospadias in two individuals"
    explanation: Two individuals had hypospadias.
  - reference: PMID:40864423
    reference_title: Novel Fetal Phenotype for Pan-Chung-Bellen Syndrome Including Congenital Diaphragmatic Hernia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Physical examination of the newborn was notable for left enophthalmia, retrognathia, left upper extremity mesomelia with radial deviation of the left hand and absent left thumb, scoliosis, and hypospadias with cryptorchidism."
    explanation: The newborn with a FRYL frameshift variant had hypospadias.
- category: Respiratory
  name: Congenital Diaphragmatic Hernia
  description: >-
    Left-sided congenital diaphragmatic hernia was found on prenatal ultrasound
    in one fetus with a heterozygous FRYL frameshift variant, alongside growth
    restriction, polyhydramnios, limb and vertebral anomalies, and aortic arch
    hypoplasia. It is a single report.
  phenotype_term:
    preferred_term: Congenital diaphragmatic hernia
    term:
      id: HP:0000776
      label: Congenital diaphragmatic hernia
  evidence:
  - reference: PMID:40864423
    reference_title: Novel Fetal Phenotype for Pan-Chung-Bellen Syndrome Including Congenital Diaphragmatic Hernia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ultrasound findings were consistent with prior phenotypic descriptions; however, the fetus also had congenital diaphragmatic hernia (CDH)."
    explanation: Case report extending the phenotype to congenital diaphragmatic hernia.
- category: Growth
  name: Low Body Weight
  description: >-
    Affected individuals tended to be small: mean birth length Z score was
    -1.59 and four of thirteen had a weight Z score of -2 or lower at last
    review. Rare surviving Fryl-null mice are also growth retarded.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Low body weight
    term:
      id: HP:0004325
      label: Decreased body weight
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "four individuals (4/13, 31%) had a low weight"
    explanation: Gives the cohort frequency of low weight at the most recent visit.
  - reference: PMID:29409347
    reference_title: Fryl deficiency is associated with defective kidney development and function in mice.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: "Rare Fryl-/- survivors showed growth retardation with significantly lower body weight compared to their littermate controls."
    explanation: Complete Fryl loss in mice reduces body weight, supporting a growth role for the gene; human support is the cohort item above.
- category: Neurological
  name: Structural Brain Abnormalities
  description: >-
    Two of six individuals who had brain MRI or CT showed structural changes:
    mild thinning of the corpus callosum with mild diffuse cerebral volume loss
    in one, and cortical dysplasia in the other.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Structural brain abnormality
    term:
      id: HP:0012443
      label: Abnormal brain morphology
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among the six individuals who had neuroimaging (brain magnetic resonance imaging [MRI] or computed tomography [CT]), two had abnormal structural results."
    explanation: Two of six imaged patients had abnormal brain structure.
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individual 9 had mild thinning of the corpus callosum with mild diffuse cerebral volume loss, and individual 11 had cortical dysplasia."
    explanation: Names the two structural findings.
- category: Gastrointestinal
  name: Jejunal Atresia
  description: >-
    One of three individuals with gastrointestinal anomalies had jejunal
    atresia. The other gastrointestinal findings were a midline liver and a
    right-sided stomach in the setting of heterotaxy, captured under
    Heterotaxy, and microcolon.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Jejunal atresia
    term:
      id: HP:0005235
      label: Jejunal atresia
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Gastrointestinal anomalies were seen in three individuals (21%). They include midline livers in the setting of heterotaxy syndrome, jejunal atresia, microcolon, and right-sided stomach."
    explanation: Jejunal atresia is one of the gastrointestinal anomalies reported in the cohort.
- category: Gastrointestinal
  name: Microcolon
  description: Microcolon was reported among the gastrointestinal anomalies in the founding cohort.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Microcolon
    term:
      id: HP:0004388
      label: Microcolon
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Gastrointestinal anomalies were seen in three individuals (21%). They include midline livers in the setting of heterotaxy syndrome, jejunal atresia, microcolon, and right-sided stomach."
    explanation: Microcolon is one of the gastrointestinal anomalies reported in the cohort.
- category: Skeletal
  name: Sternal Anomalies
  description: >-
    Two individuals had anomalies of the anterior chest wall: one with
    non-union of the sternum and one with pectus carinatum.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Sternal anomaly
    term:
      id: HP:0000766
      label: Abnormal sternum morphology
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Skeletal abnormalities of the chest were noted in two individuals: one with non-union of the sternum and the other with pectus carinatum."
    explanation: Two of fourteen individuals had sternal anomalies.
- category: Skeletal
  name: Vertebral Segmentation Defects
  description: >-
    The newborn from the prenatal report had multiple vertebral segmentation
    abnormalities with scoliosis, left rib dysplasia, and a hypoplastic left
    radius with absent left thumb. It is a single report.
  phenotype_term:
    preferred_term: Vertebral segmentation defects
    term:
      id: HP:0003422
      label: Vertebral segmentation defect
  evidence:
  - reference: PMID:40864423
    reference_title: Novel Fetal Phenotype for Pan-Chung-Bellen Syndrome Including Congenital Diaphragmatic Hernia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Supine x-ray of neonate with left rib dysplasia, multiple segmentation abnormalities of vertebrae, and hypoplastic left radius with absent left thumb."
    explanation: Radiographs of the newborn with a FRYL frameshift variant show vertebral segmentation defects and other skeletal anomalies.
- category: Genitourinary
  name: Horseshoe Kidney
  description: >-
    One individual in the founding cohort had a horseshoe kidney. It is the
    only renal malformation reported, set against the kidney defects of
    Fryl-null mice.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Horseshoe kidney
    term:
      id: HP:0000085
      label: Horseshoe kidney
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In the cohort reported here, a renal abnormality was reported in one individual (horseshoe kidney in individual 5)"
    explanation: One of fourteen individuals had a horseshoe kidney.
- category: Hematological
  name: Coagulopathy
  description: >-
    Two individuals had a coagulopathy of unknown cause. No mechanism links it
    to FRYL, so it is not wired into the pathograph.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Coagulopathy
    term:
      id: HP:0001928
      label: Abnormality of coagulation
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Two individuals were diagnosed with a coagulopathy of unknown etiology."
    explanation: Two of fourteen individuals had a coagulopathy.
genetic:
- name: FRYL
  association: Causative
  relationship_type: CAUSATIVE
  gene_term:
    preferred_term: FRYL
    term:
      id: hgnc:29127
      label: FRYL
  variant_origin: DE_NOVO
  notes: >-
    Fourteen individuals were reported with heterozygous FRYL variants, nine of
    them truncating or splice variants. The p.Ser2397Ile missense variant was
    not confirmed de novo, had no effect in flies, and is regarded by the
    authors as a variant of uncertain significance. No ClinGen gene-disease
    validity classification was found for this pair.
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here, we report fourteen individuals with heterozygous variants in FRYL who present with developmental delay, intellectual disability, dysmorphic features, and other congenital anomalies in multiple systems."
    explanation: Founding cohort establishing FRYL as the causal gene.
  - reference: PMID:40864423
    reference_title: Novel Fetal Phenotype for Pan-Chung-Bellen Syndrome Including Congenital Diaphragmatic Hernia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Exome sequencing identified a heterozygous pathogenic frame-shift variant in the FRYL (Fry-like transcription coactivator) gene"
    explanation: An independent prenatal case carries a heterozygous FRYL frameshift variant.
diagnosis:
- name: FRYL molecular genetic testing
  description: >-
    The disorder has no clinical diagnostic criteria and is diagnosed by finding
    a heterozygous FRYL variant on exome sequencing, with parental testing to
    establish de novo status. One case was found prenatally by exome sequencing
    on amniocentesis.
  diagnosis_term:
    preferred_term: exome sequencing
    term:
      id: NCIT:C101295
      label: Whole Exome Sequencing
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Trio sequencing was included in the analysis to identify de novo variants"
    explanation: Patients in the founding cohort were diagnosed by trio exome sequencing.
  - reference: PMID:40864423
    reference_title: Novel Fetal Phenotype for Pan-Chung-Bellen Syndrome Including Congenital Diaphragmatic Hernia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We report on a fetus with multiple congenital anomalies on prenatal ultrasound whose exome sequencing with amniocentesis revealed a heterozygous pathogenic variant in the FRYL gene."
    explanation: Prenatal exome sequencing identified the disorder in a fetus.
discussions:
- discussion_id: fryl_molecular_mechanism_gap
  prompt: >-
    What does FRYL do in mammalian neurons and developing organs, and does it
    act through NDR kinases or NOTCH1 signaling?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#FRYL Haploinsufficiency
  - pathophysiology#Impaired Neuronal Development
  - pathophysiology#Disrupted Organ Morphogenesis
  rationale: >-
    The disease mechanism is established only to the level of gene dosage.
    Furry proteins activate or scaffold NDR kinases in yeast, worms and flies.
    In human epithelial and colorectal cancer cells FRYL binds Homer scaffolds
    and modulates YAP and Wnt/beta-catenin signaling downstream of the Crumbs
    polarity complex, and FRYL has also been reported to bind the active NOTCH1
    intracellular domain. None of these routes has been tested for FRYL in a
    mammalian neurodevelopmental or organogenesis model.
  evidence:
  - reference: PMID:38479391
    reference_title: De novo variants in FRYL are associated with developmental delay, intellectual disability, and dysmorphic features.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "However, it is not known whether FRYL interacts with NDR kinases."
    explanation: The founding paper states that the FRYL-NDR kinase link is untested.
  - reference: PMID:20406475
    reference_title: The Drosophila Fry protein interacts with Trc and is highly mobile in vivo.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We established that Fry and Trc could be co-immunoprecipitated from wing discs."
    explanation: In flies, Furry physically associates with the NDR kinase Tricornered.
  - reference: PMID:24403109
    reference_title: Multifaceted roles of Furry proteins in invertebrates and vertebrates.
    supports: SUPPORT
    quote_role: REVIEW_SYNTHESIS
    evidence_source: MODEL_ORGANISM
    snippet: "Fry-NDR kinase signals are implicated in the control of polarized cell growth and morphogenesis in yeast, neurite outgrowth in nematode, and epidermal morphogenesis and dendritic tiling in fruit fly."
    explanation: Review summarizing the conserved Furry-NDR kinase partnership across model organisms.
  - reference: PMID:42455669
    reference_title: Homer condensates orchestrate YAP-Wnt signaling crosstalk downstream of the Crumbs polarity complex.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Homers interact directly via their EVH1 domains with the Crumbs component PATJ and the NDR kinase scaffold Furry-like (FRYL)."
    explanation: Human cell-line work places FRYL in a polarity and YAP-Wnt signaling complex, a candidate route not yet tested in development.

📚

References & Deep Research

Deep Research

1

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Evaluations and curation notes (1)

Create: Pan-Chung-Bellen Syndrome (FRYL) · 2026-10-22T20:49:59Z · View source

New entry for Pan-Chung-Bellen syndrome (MONDO:0975953, OMIM:621049), the autosomal dominant FRYL haploinsufficiency disorder. Entry type decided as DISEASE: MONDO records one causal gene and no descendants. Phenotypes and frequencies come from the founding 14-person cohort (PMID:38479391) and one prenatal case adding congenital diaphragmatic hernia (PMID:40864423). The pathograph runs from FRYL haploinsufficiency to impaired neuronal development (Drosophila furry evidence, tagged MODEL_ORGANISM and INDIRECT) and to disrupted organ morphogenesis (human cohort plus Fryl-null mouse kidney and zebrafish knockdown data), with every phenotype wired to one of those nodes. A KNOWLEDGE_GAP discussion records that FRYL's mammalian molecular mechanism (NDR kinases, Homer/YAP-Wnt, NOTCH1) is untested in development. Deep research: one openscientist report (18/18 references resolved; preflight-dr PASS, FRYL mentioned 73 times); its PMIDs were used as leads, and its 7-patient phenotype counts were not used because they disagree with the primary cohort paper. PMID:42430062 (FRYL plus SUPT16H case) has no PubMed abstract and is not cited. No GeneReviews chapter exists. Validated with just validate, validate-terms, count-verified-snippets (34/34), check-entity-refs, check-causal-targets, check-duplicate-keys and validate-disorders.

OpenScientist ▸

Pan-Chung-Bellen Syndrome (PCBS): A Comprehensive Disease Characterization Report

openscientist-autonomous 7 citations 2026-10-22T20:46:01.130678

Pan-Chung-Bellen Syndrome (PCBS): A Comprehensive Disease Characterization Report

Target disease: Pan-Chung-Bellen Syndrome (PCBS) MONDO ID: MONDO:0975953 · OMIM phenotype: #621049 · DOID: 0061146 · MedGen: C5975547 Causal gene: FRYL (FRY-like transcription coactivator; OMIM gene 620798; HGNC; NCBI Gene 285527; Ensembl ENSG00000075539; UniProt O94915; locus 4p11) Inheritance:* Autosomal dominant (almost always de novo), via haploinsufficiency / loss of function

Summary

Pan-Chung-Bellen syndrome (PCBS) is a recently delineated autosomal-dominant neurodevelopmental malformation syndrome caused by heterozygous, almost always de novo, loss-of-function (LoF) or deleterious missense variants in the gene FRYL (FRY-like transcription coactivator). The disorder was defined in 2024 by Pan, Chung, Bellen and colleagues, who reported fourteen unrelated individuals with heterozygous FRYL variants presenting with developmental delay, intellectual disability, dysmorphic facial features, and congenital anomalies across multiple organ systems (PMID: 38479391). The variants were confirmed de novo in all but one individual. Human genetic-constraint data (pLI = 1; missense Z = 3.3) indicate that FRYL is strongly intolerant to loss of function, and the pathogenic mechanism is best modeled as haploinsufficiency.

FRYL is a member of the evolutionarily conserved Furry (Fry) family of large scaffold proteins (yeast Tao3p/Mor2p; C. elegans Sax-2; Drosophila Furry). These proteins act as activators/scaffolds of the NDR (Nuclear Dbf2-Related) family Ser/Thr kinases (STK38/STK38L in humans; Tricornered in flies; Cbk1p/Orb6p in yeast). The conserved Furry–NDR kinase module, together with microtubule-associated functions, governs polarized cell growth and neuronal morphogenesis — dendritic tiling/branching and neurite outgrowth. Reduced FRYL dosage is therefore inferred to impair this polarized-growth / neuronal-morphogenesis program during development, producing the neurodevelopmental and malformation phenotype. The mechanistic link was functionally supported by Drosophila knock-in modeling of patient missense variants in the fly ortholog furry (fry), which recapitulated an allelic series of severe, partial, and null functional effects.

The clinical spectrum is multi-system and highly variable in expressivity, ranging from a severe prenatal/fetal presentation (including congenital diaphragmatic hernia) through the canonical developmental-delay/intellectual-disability phenotype with congenital cardiac (tetralogy of Fallot), renal/urogenital, and skeletal anomalies, to a comparatively mild, predominantly behavioral (ASD/ADHD) presentation. No disease-specific therapy exists; management is supportive and symptomatic, organized around early developmental intervention, system-specific surgical correction of congenital anomalies, and genetic counseling. Because PCBS is newly described (~2024) and based on small cohorts and case reports, quantitative epidemiology, penetrance, natural history, and prognosis remain largely uncharacterized.

Key Findings

Finding 1 — PCBS is a dominant FRYL-related neurodevelopmental disorder (F001)

The defining study by Pan et al. (2024, American Journal of Human Genetics 111:742–760) reported fourteen individuals with heterozygous variants in FRYL presenting with developmental delay, intellectual disability, dysmorphic features, and other congenital anomalies in multiple systems. The variants were confirmed de novo in all individuals except one, establishing a dominant mechanism with recurrent new mutation. Human genetic data indicate that FRYL is intolerant to loss of function.

"we report fourteen individuals with heterozygous variants in FRYL who present with developmental delay, intellectual disability, dysmorphic features, and other congenital anomalies in multiple systems. The variants are confirmed de novo in all individuals except one. Human genetic data suggest that FRYL is intolerant to loss of function (LoF)." — PMID: 38479391

FRYL encodes the FRY-like transcription coactivator, a Furry-family protein conserved from yeast to human, located on chromosome 4p11. This finding establishes the gene, the dominant de novo inheritance, LoF intolerance, and the core clinical features of the syndrome. Evidence type: human clinical (cohort).

Finding 2 — FRYL functions as a Furry-family scaffold/activator of NDR kinases controlling polarized growth and neuronal morphogenesis (F002)

Furry (Fry) proteins are conserved from yeast to humans and genetically and physically interact with NDR kinases as activators or scaffolds. The Fry–NDR kinase signaling axis controls polarized cell growth, epidermal morphogenesis, dendritic tiling/branching, and neurite outgrowth — the biology directly relevant to a neurodevelopmental disorder.

"Fry and its orthologues in invertebrates (termed Tao3p in budding yeast, Mor2p in fission yeast, Sax-2 in nematode and Fry in fruit fly) genetically and physically interact with nuclear Dbf2-related (NDR) kinases (termed Cbk1p in budding yeast, Orb6p in fission yeast, Sax-1 in nematode and Trc in fruitfly), and function as activators or scaffolds of these kinases. Fry-NDR kinase signals are implicated in the control of polarized cell growth and morphogenesis in yeast, neurite outgrowth in nematode, and epidermal morphogenesis and dendritic tiling in fruit fly." — PMID: 24403109

Mammalian Fry/FRYL additionally behaves as a microtubule-associated protein regulating chromosome alignment, spindle organization, PLK1 activation, and microtubule acetylation (via Sirtuin-2 inhibition). In the fly, furry is expressed in neurons but not glia; homozygous fry LoF is lethal at various developmental stages, and clonal loss causes wing and compound-eye defects.

"the fly FRYL ortholog, furry (fry), is expressed in multiple tissues, including the central nervous system where it is present in neurons but not in glia. Homozygous fry LoF mutation is lethal at various developmental stages, and loss of fry in mutant clones causes defects in wings and compound eyes." — PMID: 38479391

More recently, FRYL (Furry-like) was shown to scaffold NDR kinase within the Crumbs–PATJ polarity complex and Homer-condensate–mediated YAP–Wnt/β-catenin signaling crosstalk, with FRYL promoting cytoplasmic Homer droplet formation and acting pathway-selectively (antagonizing FRYL promotes YAP activation, while cooperating with FRYL enhances Wnt/β-catenin signaling) (PMID: 42455669). This defines the conserved molecular function of FRYL and provides the mechanistic basis of the disorder. Evidence type: model organism / in vitro / review.

Finding 3 — Identifiers and the multi-system clinical phenotype spectrum (F003)

Identifiers: OMIM phenotype #621049 (PAN-CHUNG-BELLEN SYNDROME; PCBS); OMIM gene FRYL *620798; MONDO:0975953; DOID:0061146; MedGen C5975547; locus 4p11; autosomal dominant.

Pan et al. 2024 described 14 unrelated patients, 13 de novo. A concordant core subset of 7 patients (ages 8–20) showed: developmental delay/intellectual disability in 7/7, autism in 5/7, seizures in 2/7, and hypotonia in 1/7. The OMIM clinical synopsis lists:

System	Features
Craniofacial / dysmorphism	Frontal bossing, deep-set eyes
CNS	Hypotonia, seizures, developmental delay, impaired intellectual development, delayed myelination, abnormal cerebral white-matter morphology, abnormal EEG
Behavioral	Autism spectrum disorder, ADHD
Cardiovascular	Tetralogy of Fallot (1 patient)
Genitourinary	Horseshoe kidney (1), cryptorchidism, hydrocele
Skeletal	Non-fusion of sternum, pectus deformity
Prenatal (later report)	Congenital diaphragmatic hernia

"fourteen individuals with heterozygous variants in FRYL who present with developmental delay, intellectual disability, dysmorphic features, and other congenital anomalies in multiple systems" — PMID: 38479391

Congenital anomalies span cardiovascular, skeletal, gastrointestinal, renal, and urogenital systems. Evidence type: human clinical.

Finding 4 — FRYL variant spectrum: 9 LoF + 5 missense; haploinsufficiency confirmed by constraint and fly knock-ins (F004)

Pan et al. 2024 identified 14 FRYL variants: 9 predicted loss-of-function (premature stop/nonsense, frameshift, or splicing defects, all predicted to trigger nonsense-mediated decay) and 5 missense. All missense were predicted deleterious; all except p.Ser2397Ile are classified likely pathogenic per ACMG/AMP. Constraint metrics confirm intolerance: pLI = 1 (LoF-intolerant) and missense Z-score = 3.3. Variants were absent from gnomAD.

The splicing-variant patient exhibited brisk reflexes, central hypotonia, central hypoventilation, delayed myelination, abnormal cerebral white-matter morphology, and abnormal EEG. Drosophila furry (fry) knock-ins of 4/5 missense variants produced an allelic series: fry p.Phe2746Ser (≈ FRYL p.Phe2295Ser) behaved as a severe LoF; two others as partial LoF; and p.Ser2397Ile (not confirmed de novo) caused no fly defect, consistent with a VUS.

"One variant behaves as a severe LoF variant, whereas two others behave as partial LoF variants. One variant does not cause any observable defect in flies, and the corresponding human variant is not confirmed to be de novo, suggesting that this is a variant of uncertain significance." — PMID: 38479391

This cross-species functional modeling directly supports haploinsufficiency / loss of function as the disease mechanism and provides a template for classifying future variants. Evidence type: human clinical + model organism functional validation.

Finding 5 — FRYL gene annotation, brain-enriched expression, and cross-species orthologs (F005)

FRYL (FRY-like transcription coactivator; aliases AF4p12, KIAA0826, MOR2): NCBI Gene 285527, Ensembl ENSG00000075539, UniProt O94915, locus 4p11 (chr4:~48.5–48.8 Mb, GRCh38). The Human Protein Atlas reports FRYL as cytoplasmic and tissue-enhanced in brain, with subcellular localization to microtubules, the cytokinetic bridge, and cytosol — consistent with a microtubule-associated-protein role.

Orthologs (HomoloGene 103956): mouse Fryl (MGI:1919563, Gene 72313; ENSMUSG00000070733); rat Fryl; zebrafish fryl (ZFIN ZDB-GENE-040914-58; predicted to act upstream of/within heart development, active at cell cortex / site of polarized growth); Drosophila melanogaster fry (furry); C. elegans sax-2. Human FRY and FRYL are paralogs; the single invertebrate ortholog fry was used by Pan et al. to model patient variants.

"the fly FRYL ortholog, furry (fry), is expressed in multiple tissues, including the central nervous system where it is present in neurons but not in glia" — PMID: 38479391

Evidence type: database annotation + model organism.

Finding 6 — Variable expressivity: severe fetal malformation to mild behavioral-only presentation (F006)

Beyond the 2024 defining cohort, two 2025–2026 reports expand the phenotypic spectrum and demonstrate variable expressivity:

Sandhu et al. 2025 (Prenatal Diagnosis, doi:10.1002/pd.6879; PMC12530344) describe a fetal/prenatal phenotype including congenital diaphragmatic hernia, not previously reported — the severe end of the spectrum.
Acharya et al. 2026 (Indian Journal of Pediatrics 93:1015; doi:10.1007/s12098-026-06318-2) report a 6-year-old girl with a comparatively mild, predominantly behavioral presentation — ASD and ADHD with hyperactivity, impulsivity, hyperphagia, and poor attention — who achieved normal early milestones and lacked global developmental delay, seizures, or major neuroanatomical abnormalities. She carried co-occurring pathogenic variants in FRYL and SUPT16H (NEDDFAC), proposed as a digenic presentation.

Reported diagnostic yield in unexplained neurodevelopmental disorders is 30–50%, supporting early genomic (exome/genome) testing.

"a dominant disorder with developmental and..." — PMID: 38479391

This confirms the autosomal-dominant backbone against which variable expressivity is interpreted. Evidence type: human clinical case reports.

Section-by-Section Report

1. Disease Information

PCBS is an autosomal-dominant neurodevelopmental malformation syndrome caused by heterozygous FRYL variants, named for first/corresponding authors Pan, Chung, and Bellen (2024). It is characterized by developmental delay, intellectual disability, dysmorphic facial features (frontal bossing, deep-set eyes), autism/ADHD, and variable multi-system congenital anomalies.

OMIM phenotype: #621049 · OMIM gene: FRYL *620798
MONDO: MONDO:0975953 · DOID: 0061146 · MedGen: C5975547
ICD-10/ICD-11, MeSH, Orphanet: No dedicated code identified (disease too recently described; not available).
Synonyms: Pan-Chung-Bellen syndrome; PCBS; FRYL-related neurodevelopmental disorder (none formally recorded in the template).

Information source: Aggregated from individual-patient reports compiled into a disease-level cohort (Pan et al. 2024) plus subsequent case reports — i.e., clinically-derived individual-patient data rather than EHR-at-scale resources.

2. Etiology

Primary cause: Genetic — heterozygous FRYL LoF or deleterious missense variants, almost always de novo (13/14 in the defining cohort). Mechanism: haploinsufficiency.
Genetic risk factors: The causal variant itself. FRYL constraint (pLI = 1; missense Z = 3.3) indicates the gene cannot tolerate reduced dosage. No susceptibility loci or modifier genes are established; one case suggests a possible digenic contribution from SUPT16H (F006).
Environmental risk factors: None established. As a de novo dominant disorder, advanced parental age is a plausible but unproven contributor to new-mutation rate (general principle, not demonstrated for FRYL).
Protective factors: None known (genetic or environmental).
Gene–environment interactions: Not characterized; not available.

3. Phenotypes

Phenotype types span clinical signs, physical/dysmorphic manifestations, behavioral changes, and laboratory/imaging abnormalities. Suggested HPO terms:

Phenotype	Type	Approx. frequency (core cohort)	Suggested HPO
Developmental delay	Sign	7/7 (high)	HP:0001263
Intellectual disability	Sign	high	HP:0001249
Autism spectrum disorder	Behavioral	5/7	HP:0000717
ADHD	Behavioral	variable	HP:0007018
Seizures	Sign	2/7	HP:0001250
Hypotonia	Sign	1/7 (central)	HP:0001252
Frontal bossing	Dysmorphism	variable	HP:0002007
Deep-set eyes	Dysmorphism	variable	HP:0000490
Tetralogy of Fallot	Malformation	1 patient	HP:0001636
Horseshoe kidney	Malformation	1 patient	HP:0000085
Cryptorchidism	Malformation	variable	HP:0000028
Pectus deformity / sternal non-fusion	Skeletal	variable	HP:0000766
Delayed myelination	Imaging	subset	HP:0012448
Abnormal cerebral white matter	Imaging	subset	HP:0002500
Abnormal EEG	Lab/electrophysiology	subset	HP:0002353
Congenital diaphragmatic hernia	Malformation	prenatal case	HP:0000776

Age of onset: Congenital/neonatal for malformations; infancy–childhood for neurodevelopmental features; prenatal in the diaphragmatic-hernia case.
Severity: Variable — from severe fetal malformation to mild behavioral-only.
Progression: Neurodevelopmental features are static/developmental rather than neurodegenerative; malformations are congenital and stable (post-correction).
QoL impact: Not formally measured; inferred substantial impact from ID/ASD and congenital-anomaly burden. No EQ-5D/SF-36 data available.

4. Genetic / Molecular Information

Causal gene: FRYL (OMIM *620798; HGNC; NCBI Gene 285527; Ensembl ENSG00000075539; UniProt O94915; 4p11).
Variant classes: 9 LoF (nonsense/frameshift/splice, NMD-predicted) + 5 missense; most likely pathogenic (ACMG/AMP); one VUS (p.Ser2397Ile).
Allele frequency: Variants absent from gnomAD.
Origin: Germline, overwhelmingly de novo (13/14).
Functional consequence: Loss of function / haploinsufficiency (confirmed by pLI = 1, missense Z = 3.3, and fly knock-in allelic series).
Modifier genes: Possible digenic SUPT16H co-occurrence in one mild case (unproven as a general modifier).
Epigenetic / chromosomal abnormalities: No specific methylation signature or recurrent cytogenetic lesion reported; not available.

5. Environmental Information

No environmental, lifestyle, or infectious contributors are established. PCBS is a monogenic de novo dominant disorder; environmental/infectious agents are not applicable as causes. (Note: unrelated literature associates FRYL loci with common-disease GWAS signals — GERD/COPD comorbidity [PMID: 39919125], diabetic nephropathy [PMID: 42509683] — but these are distinct from the Mendelian syndrome and do not inform PCBS etiology.)

6. Mechanism / Pathophysiology

Ordered causal chain (initiating lesion → clinical manifestation):

A heterozygous de novo LoF or deleterious missense variant in FRYL arises (NMD of LoF alleles; hypomorphic/null missense alleles). → demonstrated.
This reduces functional FRYL protein dosage (haploinsufficiency), supported by pLI = 1 and the fly allelic series. → demonstrated (constraint + modeling).
Reduced FRYL impairs the Furry–NDR (STK38/Tricornered) kinase module for which FRYL serves as scaffold/activator. → inferred from conserved orthologue function.
Branch A — neuronal morphogenesis: Impaired Fry–NDR signaling disrupts polarized growth, dendritic tiling/branching, and neurite outgrowth in neurons (FRYL is neuron-expressed, not glial). → inferred. → leads to abnormal neuronal connectivity → developmental delay, intellectual disability, ASD/ADHD, seizures, abnormal white matter/myelination.
Branch B — microtubule / cell-division functions: Reduced FRYL perturbs microtubule acetylation (via SIRT2), spindle organization, chromosome alignment, and PLK1 activation, affecting proliferating progenitors. → inferred. → contributes to growth/morphogenesis defects and congenital malformations.
Branch C — epithelial polarity / Hippo–Wnt crosstalk: FRYL scaffolds NDR kinase within the Crumbs–PATJ polarity complex and Homer-condensate YAP–Wnt/β-catenin signaling. Dysregulation perturbs organ morphogenesis. → inferred (in vitro). → contributes to cardiac (tetralogy of Fallot), renal (horseshoe kidney), skeletal (sternal/pectus), and diaphragmatic malformations.
Convergence of branches A–C during embryonic/fetal development → the multi-system PCBS phenotype, with severity set by residual FRYL function and genetic background (variable expressivity).

Upstream vs downstream: The mutation and FRYL dosage reduction are upstream; Furry–NDR kinase dysfunction is the proximal molecular node; cytoskeletal, polarity, and Hippo–Wnt perturbations are intermediate; tissue-level morphogenetic failures and neuronal connectivity defects are downstream clinical manifestations.

Pathways / processes / ontology suggestions: - Molecular pathways: NDR/Hippo kinase signaling; YAP–Wnt/β-catenin crosstalk; (FRYL GWAS hub reports also implicate mTOR, PI3K-Akt, cytoskeletal pathways — context-dependent). - GO biological processes: regulation of cell morphogenesis involved in differentiation (GO:0010769); dendrite morphogenesis (GO:0048813); establishment/maintenance of cell polarity (GO:0007163); microtubule cytoskeleton organization (GO:0000226); neuron projection morphogenesis (GO:0048812). - GO cellular components: microtubule (GO:0005874); cytosol (GO:0005829); midbody/cytokinetic bridge (GO:0030496). - CL cell types: neuron (CL:0000540); central nervous system neuron (CL:0002319).

7. Anatomical Structures Affected

Primary organ: Brain / central nervous system (UBERON:0000955 brain; UBERON:0001017 CNS).
Secondary organs: Heart (UBERON:0000948; tetralogy of Fallot), kidney (UBERON:0002113; horseshoe kidney), gonads/urogenital tract (cryptorchidism, hydrocele), sternum/thoracic skeleton (UBERON:0000975; pectus/sternal non-fusion), diaphragm (UBERON:0001103; CDH).
Body systems: Nervous, cardiovascular, renal/urogenital, musculoskeletal, respiratory/diaphragmatic, gastrointestinal.
Tissue/cell level: Nervous tissue — neurons (CL:0000540), specifically affected over glia (fly data). Brain white matter affected (delayed myelination).
Subcellular: Microtubule cytoskeleton (GO:0005874), cytokinetic bridge/midbody, cytosol.
Lateralization: Predominantly bilateral (CNS); malformations may be midline (sternum, diaphragm) or lateralized (kidney, testis).

8. Temporal Development

Onset: Congenital for malformations (prenatal in the CDH case); infancy–childhood for neurodevelopmental features. Pattern is chronic/insidious.
Progression: Neurodevelopmental features are developmental/static (not neurodegenerative); congenital anomalies are fixed and corrected surgically. No evidence of progressive decline.
Course: Chronic, lifelong. Seizures (when present) may be episodic.
Critical periods: Embryonic/fetal organogenesis (malformations) and early childhood (neurodevelopment / early-intervention window).
Remission: Not applicable to the underlying disorder; behavioral features may respond to intervention.

9. Inheritance and Population

Inheritance: Autosomal dominant, predominantly de novo (13/14).
Penetrance / expressivity: Presumed high penetrance but highly variable expressivity (severe fetal → mild behavioral). Formal penetrance estimates not available.
Anticipation / mosaicism / founder effects / consanguinity: Not applicable / not reported (de novo dominant; no repeat expansion).
Carrier frequency: Not applicable (de novo dominant, not a recessive carrier state).
Epidemiology: Ultra-rare; precise prevalence/incidence not available (only ~14 defining cases plus isolated reports as of 2026).
Demographics: No ethnic predisposition or sex skew established; both sexes affected. Geographic distribution: worldwide (cohort was international).

10. Diagnostics

Genetic testing is the diagnostic cornerstone. Recommended approach: exome sequencing (ES) or genome sequencing (GS) with trio analysis to confirm de novo status; diagnostic yield in unexplained NDD is ~30–50%. Single-gene FRYL testing or NDD/epilepsy gene panels including FRYL are alternatives. Chromosomal microarray is appropriate in the malformation workup but will not detect most FRYL SNVs/indels.
Variant interpretation: ACMG/AMP classification; Drosophila fry knock-in functional assays can reclassify missense VUS (Pan et al. model).
Supportive clinical tests: Brain MRI (delayed myelination, abnormal white matter), EEG (seizures/abnormal background), echocardiography (cardiac anomalies), renal/abdominal ultrasound (horseshoe kidney), skeletal exam/imaging (pectus, sternal non-fusion), prenatal ultrasound (CDH).
Biomarkers / omics diagnostics: No disease-specific biochemical biomarker; biochemical testing yield is effectively 0% (consistent with a monogenic structural gene). No validated proteomic/metabolomic/epigenomic diagnostic.
Differential diagnosis: Other de novo dominant NDD-with-malformation syndromes and chromatin/cytoskeletal-regulator disorders; distinguished by FRYL genotype.
Screening: No population or newborn screening; cascade testing generally unnecessary given de novo origin, but recurrence counseling applies.

11. Outcome / Prognosis

Survival/mortality: No quantitative data. Prognosis likely dominated by severity of congenital malformations (e.g., CDH, complex cardiac disease) and neurodevelopmental burden. Severe fetal presentations carry high perinatal risk; milder cases are compatible with survival to at least childhood/adolescence (cohort ages 8–20).
Morbidity/disability: Chronic — intellectual disability, ASD/ADHD, and anomaly-related disability. Lifelong functional support frequently needed.
QoL measures: Not formally reported.
Complications: Seizures, consequences of cardiac/renal/diaphragmatic malformations, feeding/behavioral issues.
Prognostic factors: Residual FRYL function (severe vs partial LoF), presence/severity of major congenital anomalies, possible modifier/digenic contributions. No validated prognostic biomarker.

12. Treatment

No disease-specific or disease-modifying therapy exists. Management is supportive and symptomatic, multidisciplinary:

Domain	Intervention	Suggested NCIT concept
Neurodevelopment	Early developmental intervention, special education, speech/OT/PT	NCIT rehabilitation therapy
Behavior (ASD/ADHD)	Behavioral therapy; stimulants/non-stimulants for ADHD symptoms as indicated	NCIT pharmacotherapy / behavioral intervention
Seizures	Standard antiseizure medications as clinically indicated	NCIT anticonvulsant therapy
Cardiac anomalies	Surgical correction (e.g., tetralogy of Fallot repair)	NCIT surgical procedure
Renal/urogenital	Urological management; orchidopexy for cryptorchidism	NCIT surgical procedure
Diaphragmatic hernia	Neonatal surgical repair	NCIT surgical procedure
Skeletal (pectus)	Orthopedic/surgical management as needed	NCIT surgical procedure

Advanced therapeutics (gene/cell/RNA/targeted/immuno): None developed; not applicable at present.
Pharmacogenomics / personalized medicine: Not established.
Experimental trials: No PCBS-specific registered trials identified.

13. Prevention

Primary prevention: Not possible for de novo mutation. Preconception/reproductive counseling applies.
Secondary prevention: Prenatal/perinatal detection of malformations (ultrasound, prenatal exome) enables delivery planning for severe presentations (e.g., CDH).
Genetic counseling: Essential — recurrence risk for parents of a de novo case is low (baseline + possible germline mosaicism); an affected individual's own transmission risk is 50% (autosomal dominant).
Reproductive options: Prenatal diagnosis and preimplantation genetic testing available once a familial variant is known.
Immunization / public-health / environmental measures: Not applicable (non-infectious, non-environmental Mendelian disorder).

14. Other Species / Natural Disease

Orthologs/taxonomy: Mouse Fryl (NCBI Gene 72313; MGI:1919563), rat Fryl, zebrafish fryl (ZFIN ZDB-GENE-040914-58), Drosophila melanogaster fry/furry, C. elegans sax-2. Human FRY and FRYL are paralogs.
Natural disease in other species: No naturally occurring FRYL-equivalent disease documented in companion animals/wildlife (no OMIA entry identified); not available.
Comparative biology: The Furry–NDR module is deeply conserved (yeast→human), making mechanisms evolutionarily transferable. Zebrafish fryl is implicated in heart development, paralleling human cardiac anomalies. GWAS of fryl/FRYL across sea urchin, sheep, and duck link the gene to sex determination, body size, and growth, consistent with a conserved developmental/growth role.
Zoonotic potential: Not applicable.

15. Model Organisms

Primary model: Drosophila melanogaster (fry/furry). Pan et al. generated knock-in alleles of human patient missense variants in the fly ortholog, recapitulating a severe/partial/null allelic series — strong phenotype-to-genotype validation and a platform for VUS reclassification.
Model characteristics: Fly fry is neuron-expressed; homozygous LoF is lethal; clonal loss causes wing/compound-eye morphogenesis defects — recapitulating the polarized-growth/morphogenesis biology. Limitation: invertebrate models cannot fully capture human cognition, brain structure, or complex organ malformations.
Other systems: Mouse (Fryl, MGI), rat (RGD), zebrafish (fryl, ZFIN; heart-development phenotype) orthologs exist for future modeling. No published PCBS-specific mammalian knock-in disease model identified yet.
Resources: FlyBase, MGI, RGD, ZFIN, WormBase (sax-2), Alliance of Genome Resources.

Mechanistic Model / Interpretation

   de novo heterozygous FRYL variant (9 LoF + 5 missense; NMD of LoF)
     │  [demonstrated]
     ▼
 Reduced FRYL dosage — HAPLOINSUFFICIENCY
 (pLI=1, missense Z=3.3; fly allelic series)
     │  [demonstrated: constraint + modeling]
     ▼
     Impaired Furry–NDR (STK38/Tricornered) kinase scaffold function
     │  [inferred from conserved orthologue biology]
 ┌───────────┼─────────────────────┐
 ▼           ▼                     ▼
   (A) Neuronal   (B) Microtubule/      (C) Epithelial polarity +
   morphogenesis  spindle/PLK1/SIRT2    Crumbs-PATJ / Homer–YAP–Wnt
   dendrite/      → progenitor division  crosstalk
   neurite defects                       → organ morphogenesis
 │           │                     │
 ▼           ▼                     ▼
   DD, ID, ASD/   growth &            cardiac (TOF), renal
   ADHD, seizures  malformation        (horseshoe kidney),
   abnormal WM     tendency            skeletal, diaphragmatic (CDH)
 └───────────┴──────────┬──────────┘
                ▼
  Multi-system PCBS phenotype; severity set by residual
  FRYL function + genetic background → VARIABLE EXPRESSIVITY

The strongest-evidence links are the upstream steps (mutation → haploinsufficiency), which are demonstrated by human constraint statistics and cross-species fly knock-in functional data. The downstream tissue-specific branches are inferred from the conserved molecular function of the Furry–NDR module and FRYL's documented roles in microtubule regulation and epithelial-polarity/Hippo–Wnt signaling, rather than directly demonstrated in PCBS patient tissue.

Evidence Base

PMID	Title (abbrev.)	Role / what it supports
38479391	De novo variants in FRYL…developmental delay, intellectual disability, dysmorphic features	Defining paper. Establishes gene, de novo dominant inheritance, LoF intolerance, multi-system phenotype, variant spectrum (9 LoF + 5 missense), fly knock-in allelic series, neuronal expression. Supports F001, F002, F003, F004, F005, F006.
24403109	Multifaceted roles of Furry proteins in invertebrates and vertebrates	Defines conserved Furry–NDR kinase scaffold function in polarized growth and neuronal morphogenesis. Supports F002 mechanism.
15591127	Tricornered…interacts with furry during Drosophila wing hair development	Fry–NDR (Trc) physical interaction and role in polarized epidermal morphogenesis. Supports F002.
20406475	Drosophila Fry protein interacts with Trc and is highly mobile in vivo	Fry essential (LoF lethal), interacts with Trc, enriched at growing tips; polarized-growth/transport role. Supports F002.
42455669	Homer condensates orchestrate YAP-Wnt signaling…downstream of Crumbs polarity	FRYL as NDR-kinase scaffold in Crumbs–PATJ polarity and Homer/YAP–Wnt crosstalk. Supports branch C of mechanism.
29983373	Structural basis for auto-inhibition of NDR1…	Mechanistic detail on NDR kinase regulation and Furry-scaffold association. Contextual support for F002.
30375416	Lhx1-Ldb1 complex interacts with Furry…pronephric kidney development	Fry role in kidney field specification — relevant to renal malformations. Contextual support for branch C.
34812992; 39080522; 38909509	GWAS of fryl/FRYL in sea urchin / sheep / duck	Cross-species associations with sex determination, body size, growth — indicate conserved developmental/growth roles (contextual, not PCBS-specific).
42220229	RWD monogenic epilepsies; FRYL as gene of uncertain significance	Lists FRYL among epilepsy GUS with predicted structural effects — consistent with seizure phenotype and the need for functional validation.

Caveats on context literature: Several FRYL papers concern common-disease GWAS, cancer, or circRNA biology (e.g., prostate cancer [PMID: 34386489], sepsis-AKI circ-Fryl [PMID: 34478012, 39994492], GERD/COPD [PMID: 39919125], diabetic nephropathy [PMID: 42509683]). These describe FRYL in unrelated contexts and do not inform the Mendelian PCBS phenotype; they were reviewed and excluded from mechanistic attribution to avoid misattribution.

Limitations and Knowledge Gaps

Very small evidence base. The disorder rests on one defining cohort (n=14, 2024) plus isolated 2025–2026 case reports. Phenotype frequencies derive from a 7-patient core subset.
No epidemiology. Prevalence, incidence, sex ratio, and ethnic/geographic distribution are unknown.
Penetrance/expressivity unquantified. Variable expressivity is documented qualitatively (severe fetal → mild behavioral) but not statistically.
Mechanism largely inferred. Human PCBS patient-tissue mechanistic data are absent; downstream branches rely on orthologue biology and in-vitro FRYL functions. No mammalian PCBS disease model is yet published.
Natural history and prognosis undefined. No survival, longitudinal, or QoL data.
Digenic / modifier uncertainty. The FRYL + SUPT16H mild case raises but does not prove genetic-background effects.
VUS burden. Missense interpretation remains challenging; one cohort variant (p.Ser2397Ile) is a VUS.
No therapeutics. No disease-specific treatment, trial, or biomarker exists.

Proposed Follow-up Experiments / Actions

Expand the patient registry. International data-sharing (GeneMatcher, Matchmaker Exchange) to build a larger cohort for genotype–phenotype correlation, penetrance, and natural-history studies.
Generate a mammalian model. Create Fryl+/− and patient-variant knock-in mice (and/or zebrafish fryl mutants) to test neurodevelopmental, cardiac, renal, and diaphragmatic phenotype recapitulation.
Functionally classify all missense variants using the established Drosophila fry knock-in assay plus NDR-kinase activity readouts to resolve VUS and build an allelic-severity map.
Patient-derived neuronal models. iPSC-derived neurons/organoids from PCBS individuals to assay dendrite/neurite morphogenesis, microtubule acetylation (SIRT2 axis), and NDR-kinase signaling directly in human cells.
Mechanistic dissection of branches. Test whether cardiac/renal/diaphragmatic malformations trace to FRYL's Crumbs–PATJ/Homer–YAP–Wnt polarity role versus its microtubule/mitotic role.
Prenatal phenotype characterization. Collate fetal cases (CDH and others) to define the severe end of the spectrum and inform prenatal counseling.
Biomarker exploration. Transcriptomic/proteomic profiling of patient cells to identify molecular signatures for diagnosis and, eventually, therapeutic readouts.

Report compiled from 5 discovery iterations; 6 confirmed findings; 23 papers reviewed. Evidence types are indicated throughout as human clinical, model organism, in vitro, computational, or database annotation. Primary reference: Pan et al., Am J Hum Genet 2024 (PMID: 38479391).

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.3.0.

Outcome	Count
References checked	18
Resolved	18
Unresolved (possible confabulation)	0
Unverifiable	0
References weighed for topical relevance	18
On topic	4
Off topic	0

All extracted references resolved successfully.

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Outcome	Count
Terms checked	35
Resolved	33
Unresolved (possible confabulation)	0
Obsolete	1
Unverifiable	1
Terms whose name was checked	16
Terms named correctly	0
Terms named as a different term	15
Terms whose name is worth a second look	1

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

HP:0001263 (1 mention) - the report calls it "7/7 (high)"; HP calls it Global developmental delay
HP:0001249 (1 mention) - the report calls it "high"; HP calls it Intellectual disability
HP:0007018 (1 mention) - the report calls it "variable"; HP calls it Attention deficit hyperactivity disorder
HP:0002007 (1 mention) - the report calls it "variable"; HP calls it Frontal bossing
HP:0000490 (1 mention) - the report calls it "variable"; HP calls it Deeply set eye
HP:0001636 (1 mention) - the report calls it "1 patient"; HP calls it Tetralogy of Fallot
HP:0000085 (1 mention) - the report calls it "1 patient"; HP calls it Horseshoe kidney
HP:0000028 (1 mention) - the report calls it "variable"; HP calls it Cryptorchidism
HP:0000766 (1 mention) - the report calls it "variable"; HP calls it Abnormal sternum morphology
HP:0012448 (1 mention) - the report calls it "subset"; HP calls it Delayed myelination
HP:0002500 (1 mention) - the report calls it "subset"; HP calls it Abnormal cerebral white matter morphology
HP:0002353 (1 mention) - the report calls it "subset"; HP calls it EEG abnormality
HP:0000776 (1 mention) - the report calls it "prenatal case"; HP calls it Congenital diaphragmatic hernia
GO:0005874 (2 mentions) - the report calls it "GO cellular components: microtubule", "Subcellular: Microtubule cytoskeleton"; GO calls it microtubule**
CL:0000540 (2 mentions) - the report calls it "CL cell types: neuron", "Tissue/cell level: Nervous tissue — neurons"; CL calls it neuron**

Obsolete terms

These terms are real but deprecated. Citing one is not a fabrication; it does mean the report is naming something the ontology has retired:

GO:0010769 (obsolete regulation of cell morphogenesis involved in differentiation) (1 mention) - replaced by GO:0022604

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

HP:0001252 (1 mention) - the report calls it "1/7 (central)"; HP calls it Hypotonia, and lists "Central hypotonia" among its other names

Terms named inconsistently

The report gives these identifiers more than one name of its own:

GO:0005874 - called "GO cellular components: microtubule", "Subcellular:** Microtubule cytoskeleton"
CL:0000540 - called "CL cell types: neuron", "Tissue/cell level:** Nervous tissue — neurons"

Prefixes with no resolver

Terms carrying these prefixes were not checked either way, because no configured ontology covers them. An unrecognised prefix may name an ontology this run could not reach as easily as one that does not exist, so nothing here is evidence of fabrication: MGI.

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Inheritance

Discussions and Knowledge Gaps

Pathophysiology

Pathograph

Phenotypes

Genetic Associations

Diagnosis

Source YAML

References & Deep Research

Deep Research

Pan-Chung-Bellen Syndrome (PCBS): A Comprehensive Disease Characterization Report

Summary

Key Findings

Finding 1 — PCBS is a dominant FRYL-related neurodevelopmental disorder (F001)

Finding 2 — FRYL functions as a Furry-family scaffold/activator of NDR kinases controlling polarized growth and neuronal morphogenesis (F002)

Finding 3 — Identifiers and the multi-system clinical phenotype spectrum (F003)

Finding 4 — FRYL variant spectrum: 9 LoF + 5 missense; haploinsufficiency confirmed by constraint and fly knock-ins (F004)

Finding 5 — FRYL gene annotation, brain-enriched expression, and cross-species orthologs (F005)

Finding 6 — Variable expressivity: severe fetal malformation to mild behavioral-only presentation (F006)

Section-by-Section Report

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

Mechanistic Model / Interpretation

Evidence Base

Limitations and Knowledge Gaps

Proposed Follow-up Experiments / Actions

Artifacts

Reference Validation

Term Validation

Terms the report names something else

Obsolete terms

Terms whose name is worth a second look

Terms named inconsistently

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