Malan Syndrome

Mendelian MONDO:0013885 Overgrowth Syndromes Neurodevelopmental Disorders

Malan syndrome (also known as Sotos syndrome 2) is a rare autosomal dominant overgrowth disorder caused by heterozygous loss-of-function variants or deletions of the NFIX gene on chromosome 19p13.2. It is characterized by prenatal and postnatal overgrowth, macrocephaly, distinctive facial features, intellectual disability (typically moderate to severe), behavioral problems including a characteristic anxious profile, and skeletal anomalies. The condition is clinically similar to Sotos syndrome but can be distinguished by clinical evaluation.

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⚙

Pathophysiology

NFIX Haploinsufficiency

Malan syndrome results from haploinsufficiency of the NFIX transcription factor. NFIX variants causing Malan syndrome cluster in the N-terminal DNA-binding and dimerization domain (exons 2 and 3), or are whole-gene deletions. These protein-truncating variants trigger nonsense-mediated mRNA decay, resulting in loss of functional NFIX protein. This is distinct from Marshall-Smith syndrome, where NFIX variants cluster in exons 6-10 and escape NMD, producing a dominant-negative effect.

Neural progenitor cell link Neuron link

Regulation of DNA-templated transcription link ↓ DECREASED

Show evidence (3 references)

PMID:38168088 SUPPORT Human Clinical

"NFIX variants associated with Malan syndrome are missense variants mostly located in exon 2 encoding the N-terminal DNA binding and dimerization domain or are protein-truncating variants that trigger nonsense-mediated mRNA decay (NMD) resulting in NFIX haploinsufficiency."

Confirms that Malan syndrome results from NFIX haploinsufficiency through either missense variants in the DNA-binding domain or protein-truncating variants that trigger NMD.

PMID:26193383 SUPPORT Human Clinical

"The present report further adds weight to the hypothesis that mutations in DNA-binding/dimerization domain are likely to cause haploinsufficiency of the NFIX protein"

Supports that mutations in the DNA-binding domain cause haploinsufficiency as the disease mechanism.

PMID:30287093 SUPPORT Other

"One TF that contributes to these processes is Nuclear Factor One X (NFIX). Recently, NFIX activity has been shown to be essential in multiple organ systems and to have important translational impacts for human health."

Review confirming NFIX as essential in multiple organ systems including neural stem cells, muscle, and hematopoiesis.

Megalencephaly and Disrupted Brain Connectivity

NFIX haploinsufficiency causes megalencephaly through prolonged neural progenitor self-renewal and delayed differentiation. Nfix heterozygous mice exhibit significantly increased brain volume with the cerebral cortex showing the highest increase. Forebrain commissures show reduced tract density and altered microstructure, suggesting disrupted cortical connectivity that may contribute to the intellectual disability observed in patients.

Neural progenitor cell link Astrocyte link

Neurogenesis link ⚠ ABNORMAL

Show evidence (1 reference)

PMID:30503862 SUPPORT Model Organism

"Adult Nfix+/- mice exhibit significantly increased brain volume (megalencephaly) compared to wildtypes, with the cerebral cortex showing the highest increase. Moreover, all three forebrain commissures, in particular the anterior commissure, revealed significantly reduced fractional anisotropy,..."

Mouse model demonstrates that NFIX haploinsufficiency causes megalencephaly and disrupted brain connectivity, modeling the macrocephaly and intellectual disability seen in human patients.

Aortopathy Risk

A subset of patients with Malan syndrome develop aortic root dilatation and, rarely, thoracic aortic aneurysm and dissection. The pathophysiological role of NFIX in vascular tissue is not fully understood, but NFIX is known to play roles in development of brain, skeletal muscle, and hematopoietic system.

Show evidence (2 references)

PMID:28584646 SUPPORT Human Clinical

"He developed early-onset thoracic aortic aneurysm and dissection, which was a rare complication but deserves particular attention in relatively long-lived patients with Sotos-like phenotypes."

Reports the first case of aortic dissection in a 38-year-old Malan syndrome patient, establishing cardiovascular risk as a feature.

PMID:39083629 SUPPORT Human Clinical

"Four individuals with aortic root dilatation have been reported, with one adult individual experiencing progressive aortic dilation and dissection at age 38 years."

GeneReviews confirms multiple cases of aortic root dilatation and one case of dissection in Malan syndrome patients.

●

Phenotypes

Cardiovascular 1

Aortic Root Dilatation Occasional Aortic root aneurysm (HP:0002616)

Show evidence (1 reference)

PMID:28584646 SUPPORT Human Clinical

"He developed early-onset thoracic aortic aneurysm and dissection, which was a rare complication but deserves particular attention in relatively long-lived patients with Sotos-like phenotypes."

First report of aortic dissection in Malan syndrome at age 38.

Digestive 1

Constipation Constipation (HP:0002019)

Show evidence (1 reference)

PMID:39083629 SUPPORT Human Clinical

"Stool softeners, prokinetics, osmotic agents, or laxatives as needed for constipation."

GeneReviews recommends management for constipation, indicating it is a recognized feature.

Eye 1

Strabismus Frequent Strabismus (HP:0000486)

Show evidence (1 reference)

PMID:25118028 SUPPORT Human Clinical

"Ocular phenotypes are common, including strabismus (65%), nystagmus (25%) and optic disc pallor/hypoplasia (25%)."

Reports strabismus in 65% of patients.

Head and Neck 3

Macrocephaly Very frequent Macrocephaly (HP:0000256)

Show evidence (1 reference)

PMID:39083629 SUPPORT Human Clinical

"NFIX-related Malan syndrome (MALNS) is characterized by prenatal and postnatal overgrowth, macrocephaly, advanced bone age and/or skeletal anomalies"

GeneReviews lists macrocephaly as a defining feature of the syndrome.

Distinctive Facial Features Very frequent Long face (HP:0000276)

Show evidence (1 reference)

PMID:29897170 SUPPORT Human Clinical

"Cardinal facial characteristics include long, triangular face, macrocephaly, prominent forehead, everted lower lip, and prominent chin."

Large cohort confirms the characteristic facial features.

Downslanted Palpebral Fissures Very frequent Downslanted palpebral fissures (HP:0000494)

Show evidence (1 reference)

PMID:25118028 SUPPORT Human Clinical

"There is overlap of the facial phenotype with NSD1-positive Sotos syndrome in some cases including a prominent forehead, high anterior hairline, downslanting palpebral fissures and prominent chin."

Reports downslanting palpebral fissures as a recurrent facial feature.

Musculoskeletal 4

Scoliosis Occasional Scoliosis (HP:0002650)

Show evidence (1 reference)

PMID:25118028 SUPPORT Human Clinical

"Other recurrent features include pectus excavatum (40%) and scoliosis (25%)."

Reports scoliosis in 25% of patients.

Pectus Excavatum Frequent Pectus excavatum (HP:0000767)

Show evidence (1 reference)

PMID:25118028 SUPPORT Human Clinical

"Other recurrent features include pectus excavatum (40%) and scoliosis (25%)."

Reports pectus excavatum in 40% of patients.

Hypotonia Frequent Hypotonia (HP:0001252)

Show evidence (1 reference)

PMID:25118028 SUPPORT Human Clinical

"Neonatal feeding difficulties and/or hypotonia have been reported in 30% of patients."

Quantifies hypotonia/feeding difficulties at 30% frequency.

Advanced Bone Age Frequent Accelerated skeletal maturation (HP:0005616)

Show evidence (1 reference)

PMID:39083629 SUPPORT Human Clinical

"NFIX-related Malan syndrome (MALNS) is characterized by prenatal and postnatal overgrowth, macrocephaly, advanced bone age and/or skeletal anomalies"

GeneReviews lists advanced bone age as a defining feature.

Nervous System 5

Intellectual Disability Very frequent Intellectual disability (HP:0001249)

Show evidence (1 reference)

PMID:29897170 SUPPORT Human Clinical

"Intellectual disability is universally present, behaviorally anxiety is characteristic."

Large cohort study of 45 patients confirms intellectual disability is present in all affected individuals.

Anxiety Very frequent Anxiety (HP:0000739)

Show evidence (2 references)

PMID:29897170 SUPPORT Human Clinical

"Intellectual disability is universally present, behaviorally anxiety is characteristic."

Confirms anxiety as a characteristic behavioral feature in the largest cohort study.

PMID:39083629 SUPPORT Human Clinical

"behavioral problems (including a specific anxious profile and attention-deficit/hyperactivity disorder [ADHD])"

GeneReviews identifies a specific anxious profile as characteristic.

Seizures Occasional Seizure (HP:0001250)

Show evidence (1 reference)

PMID:29897170 SUPPORT Human Clinical

"There is no genotype-phenotype correlation except for an increased risk for epilepsy with 19p13.2 microdeletions."

Confirms seizure risk and genotype-phenotype correlation with deletions.

Delayed Speech and Language Development Very frequent Delayed speech and language development (HP:0000750)

Show evidence (1 reference)

PMID:25118028 SUPPORT Human Clinical

"Developmental delay/learning disability have been reported in all cases and are typically moderate."

Confirms developmental delay including speech delays in all cases.

Attention Deficit Hyperactivity Disorder Frequent Attention deficit hyperactivity disorder (HP:0007018)

Show evidence (1 reference)

PMID:39083629 SUPPORT Human Clinical

"behavioral problems (including a specific anxious profile and attention-deficit/hyperactivity disorder [ADHD])"

GeneReviews lists ADHD as a characteristic behavioral feature.

Growth 1

Overgrowth Very frequent Overgrowth (HP:0001548)

Show evidence (2 references)

PMID:29897170 SUPPORT Human Clinical

"Results indicate that height is > 2 SDS in infancy and childhood but in only half of affected adults."

Demonstrates overgrowth in childhood with partial normalization in adulthood across a large cohort.

PMID:25118028 SUPPORT Human Clinical

"The phenotype is characterised by moderate postnatal overgrowth and macrocephaly. Median height and head circumference in childhood are 2.0 and 2.3 standard deviations (SD) above the mean, respectively."

Quantifies postnatal overgrowth with median height 2.0 SD above mean.

Other 1

Optic Disc Abnormalities Occasional Optic disc pallor (HP:0000543)

Show evidence (1 reference)

PMID:25118028 SUPPORT Human Clinical

"Ocular phenotypes are common, including strabismus (65%), nystagmus (25%) and optic disc pallor/hypoplasia (25%)."

Reports optic disc pallor/hypoplasia in 25% of patients.

🧬

Genetic Associations

NFIX (Pathogenic Variants)

Autosomal dominant

Show evidence (4 references)

PMID:39083629 SUPPORT Human Clinical

"The diagnosis of MALNS is established in a proband with suggestive findings and either a heterozygous pathogenic variant in NFIX (~75% of affected individuals) OR a heterozygous deletion of 19p13.2 that includes NFIX (~25% of affected individuals) identified by molecular genetic testing."

GeneReviews provides authoritative breakdown of variant types.

PMID:29897170 SUPPORT Human Clinical

"Malan syndrome is caused by deletions or point mutations of NFIX clustered mostly in exon 2. There is no genotype-phenotype correlation except for an increased risk for epilepsy with 19p13.2 microdeletions."

Confirms mutation spectrum and clustering in exon 2.

PMID:38168088 SUPPORT Human Clinical

"Here, we report a child with clinical features of Malan syndrome who has a de novo NFIX intragenic duplication."

Expands mutation spectrum to include intragenic duplications.

+ 1 more reference

💊

Treatments

Cognitive Behavioral Therapy

Action: cognitive behavioral therapy Ontology label: cognitive behavior therapy MAXO:0000883

CBT may be used to treat anxiety and ADHD. Symptomatic aids such as colored glasses and low voice tone may reduce anxiety outbursts.

Show evidence (1 reference)

PMID:39083629 SUPPORT Human Clinical

"Cognitive behavioral therapy (CBT) may be used to treat anxiety and ADHD. Symptomatic aids (i.e., colored glasses, low voice tone) may reduce anxiety outbursts."

GeneReviews recommends CBT for behavioral management.

Developmental Support

Action: supportive care MAXO:0000950

Standard treatment for developmental delay and intellectual disability including speech therapy, occupational therapy, and educational support.

Show evidence (1 reference)

PMID:39083629 SUPPORT Human Clinical

"Standard treatment for epilepsy, Chari I malformation, developmental delay / intellectual disability, scoliosis/kyphosis, pes planus, pectus anomalies, refractive error, strabismus, tooth anomalies / malocclusion, aortic root dilatation / valvular issues, and cryptorchidism."

GeneReviews recommends standard supportive treatment for developmental and skeletal features.

Antiepileptic Medication

Action: antiepileptic drug therapy Ontology label: anticonvulsant agent therapy MAXO:0000167

Standard treatment for seizures and epilepsy in affected individuals.

Cardiovascular Surveillance

Action: echocardiography MAXO:0010203

Annual cardiology follow-up is recommended given the risk of aortic root dilatation.

Show evidence (1 reference)

PMID:39083629 SUPPORT Human Clinical

"If the baseline cardiovascular evaluation is normal, consider annual cardiology follow up; limited data on aortic root progression is available for adults."

GeneReviews recommends cardiovascular surveillance.

🌍

Environmental Factors

De Novo Occurrence

Nearly all cases arise de novo. The disorder is not associated with environmental risk factors. Rare familial cases have been attributed to parental gonadal or somatic mosaicism.

Show evidence (1 reference)

PMID:29897170 SUPPORT Human Clinical

"Variants arose de novo, except in one family in which mother was mosaic."

Confirms de novo occurrence with rare mosaicism-related familial cases.

{ }

Source YAML

click to show

name: Malan Syndrome
creation_date: "2026-03-27T12:00:00Z"
updated_date: "2026-04-22T20:13:21Z"
description: >
  Malan syndrome (also known as Sotos syndrome 2) is a rare autosomal dominant
  overgrowth disorder caused by heterozygous loss-of-function variants or deletions
  of the NFIX gene on chromosome 19p13.2. It is characterized by prenatal and
  postnatal overgrowth, macrocephaly, distinctive facial features, intellectual
  disability (typically moderate to severe), behavioral problems including a
  characteristic anxious profile, and skeletal anomalies. The condition is clinically
  similar to Sotos syndrome but can be distinguished by clinical evaluation.
category: Mendelian
disease_term:
  preferred_term: Malan overgrowth syndrome
  term:
    id: MONDO:0013885
    label: Malan overgrowth syndrome
parents:
- Overgrowth Syndromes
- Neurodevelopmental Disorders
pathophysiology:
- name: NFIX Haploinsufficiency
  description: >
    Malan syndrome results from haploinsufficiency of the NFIX transcription factor.
    NFIX variants causing Malan syndrome cluster in the N-terminal DNA-binding and
    dimerization domain (exons 2 and 3), or are whole-gene deletions. These
    protein-truncating variants trigger nonsense-mediated mRNA decay, resulting in
    loss of functional NFIX protein. This is distinct from Marshall-Smith syndrome,
    where NFIX variants cluster in exons 6-10 and escape NMD, producing a
    dominant-negative effect.
  cell_types:
  - preferred_term: Neural progenitor cell
    term:
      id: CL:0011020
      label: neural progenitor cell
  - preferred_term: Neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: Regulation of DNA-templated transcription
    term:
      id: GO:0006355
      label: regulation of DNA-templated transcription
    modifier: DECREASED
  evidence:
  - reference: PMID:38168088
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      NFIX variants associated with Malan syndrome are missense variants mostly
      located in exon 2 encoding the N-terminal DNA binding and dimerization
      domain or are protein-truncating variants that trigger nonsense-mediated
      mRNA decay (NMD) resulting in NFIX haploinsufficiency.
    explanation: >-
      Confirms that Malan syndrome results from NFIX haploinsufficiency through
      either missense variants in the DNA-binding domain or protein-truncating
      variants that trigger NMD.
  - reference: PMID:26193383
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The present report further adds weight to the hypothesis that mutations in
      DNA-binding/dimerization domain are likely to cause haploinsufficiency of
      the NFIX protein
    explanation: >-
      Supports that mutations in the DNA-binding domain cause haploinsufficiency
      as the disease mechanism.
  - reference: PMID:30287093
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      One TF that contributes to these processes is Nuclear Factor One X (NFIX).
      Recently, NFIX activity has been shown to be essential in multiple organ
      systems and to have important translational impacts for human health.
    explanation: >-
      Review confirming NFIX as essential in multiple organ systems including
      neural stem cells, muscle, and hematopoiesis.
- name: Megalencephaly and Disrupted Brain Connectivity
  description: >
    NFIX haploinsufficiency causes megalencephaly through prolonged neural progenitor
    self-renewal and delayed differentiation. Nfix heterozygous mice exhibit
    significantly increased brain volume with the cerebral cortex showing the highest
    increase. Forebrain commissures show reduced tract density and altered
    microstructure, suggesting disrupted cortical connectivity that may contribute to
    the intellectual disability observed in patients.
  cell_types:
  - preferred_term: Neural progenitor cell
    term:
      id: CL:0011020
      label: neural progenitor cell
  - preferred_term: Astrocyte
    term:
      id: CL:0000127
      label: astrocyte
  biological_processes:
  - preferred_term: Neurogenesis
    term:
      id: GO:0022008
      label: neurogenesis
    modifier: ABNORMAL
  evidence:
  - reference: PMID:30503862
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Adult Nfix+/- mice exhibit significantly increased brain volume
      (megalencephaly) compared to wildtypes, with the cerebral cortex showing the
      highest increase. Moreover, all three forebrain commissures, in particular the
      anterior commissure, revealed significantly reduced fractional anisotropy, axial
      and radial diffusivity, and tract density intensity.
    explanation: >-
      Mouse model demonstrates that NFIX haploinsufficiency causes megalencephaly
      and disrupted brain connectivity, modeling the macrocephaly and intellectual
      disability seen in human patients.
- name: Aortopathy Risk
  description: >
    A subset of patients with Malan syndrome develop aortic root dilatation and,
    rarely, thoracic aortic aneurysm and dissection. The pathophysiological role
    of NFIX in vascular tissue is not fully understood, but NFIX is known to play
    roles in development of brain, skeletal muscle, and hematopoietic system.
  evidence:
  - reference: PMID:28584646
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      He developed early-onset thoracic aortic aneurysm and dissection, which
      was a rare complication but deserves particular attention in relatively
      long-lived patients with Sotos-like phenotypes.
    explanation: >-
      Reports the first case of aortic dissection in a 38-year-old Malan
      syndrome patient, establishing cardiovascular risk as a feature.
  - reference: PMID:39083629
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Four individuals with aortic root dilatation have been reported, with one
      adult individual experiencing progressive aortic dilation and dissection
      at age 38 years.
    explanation: >-
      GeneReviews confirms multiple cases of aortic root dilatation and one
      case of dissection in Malan syndrome patients.
phenotypes:
- category: Clinical
  name: Intellectual Disability
  description: >
    Intellectual disability is universally present in Malan syndrome, typically in
    the moderate to severe range. Speech and language delays are prominent.
  frequency: Very frequent
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: PMID:29897170
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Intellectual disability is universally present, behaviorally anxiety is
      characteristic.
    explanation: >-
      Large cohort study of 45 patients confirms intellectual disability is
      present in all affected individuals.
- category: Clinical
  name: Overgrowth
  description: >
    Postnatal overgrowth with tall stature is a hallmark feature, often leading to
    initial clinical suspicion of Sotos syndrome. Height is greater than 2 standard
    deviations in infancy and childhood but normalizes in about half of affected
    adults.
  frequency: Very frequent
  phenotype_term:
    preferred_term: Overgrowth
    term:
      id: HP:0001548
      label: Overgrowth
  evidence:
  - reference: PMID:29897170
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Results indicate that height is > 2 SDS in infancy and childhood but in
      only half of affected adults.
    explanation: >-
      Demonstrates overgrowth in childhood with partial normalization in
      adulthood across a large cohort.
  - reference: PMID:25118028
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The phenotype is characterised by moderate postnatal overgrowth and
      macrocephaly. Median height and head circumference in childhood are 2.0
      and 2.3 standard deviations (SD) above the mean, respectively.
    explanation: >-
      Quantifies postnatal overgrowth with median height 2.0 SD above mean.
- category: Clinical
  name: Macrocephaly
  description: >
    Macrocephaly is a cardinal feature, with head circumference typically above the
    97th percentile. It can be detected prenatally.
  frequency: Very frequent
  phenotype_term:
    preferred_term: Macrocephaly
    term:
      id: HP:0000256
      label: Macrocephaly
  evidence:
  - reference: PMID:39083629
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      NFIX-related Malan syndrome (MALNS) is characterized by prenatal and
      postnatal overgrowth, macrocephaly, advanced bone age and/or skeletal
      anomalies
    explanation: >-
      GeneReviews lists macrocephaly as a defining feature of the syndrome.
- category: Clinical
  name: Distinctive Facial Features
  description: >
    Affected individuals have a recognizable facial gestalt including a long
    triangular face, prominent forehead with high anterior hairline, deep-set eyes,
    downslanted palpebral fissures, short nose with anteverted nares, long philtrum,
    thin upper lip vermilion, everted lower lip, and prominent chin.
  frequency: Very frequent
  phenotype_term:
    preferred_term: Long face
    term:
      id: HP:0000276
      label: Long face
  evidence:
  - reference: PMID:29897170
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cardinal facial characteristics include long, triangular face,
      macrocephaly, prominent forehead, everted lower lip, and prominent chin.
    explanation: >-
      Large cohort confirms the characteristic facial features.
- category: Clinical
  name: Anxiety
  description: >
    A specific anxious behavioral profile is characteristic. Behavioral problems
    also include attention-deficit/hyperactivity disorder (ADHD).
  frequency: Very frequent
  phenotype_term:
    preferred_term: Anxiety
    term:
      id: HP:0000739
      label: Anxiety
  evidence:
  - reference: PMID:29897170
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Intellectual disability is universally present, behaviorally anxiety is
      characteristic.
    explanation: >-
      Confirms anxiety as a characteristic behavioral feature in the largest
      cohort study.
  - reference: PMID:39083629
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      behavioral problems (including a specific anxious profile and
      attention-deficit/hyperactivity disorder [ADHD])
    explanation: >-
      GeneReviews identifies a specific anxious profile as characteristic.
- category: Clinical
  name: Seizures
  description: >
    Seizures or EEG abnormalities are reported in a significant proportion of
    patients. There is an increased risk for epilepsy in patients with 19p13.2
    microdeletions compared to point mutations.
  frequency: Occasional
  phenotype_term:
    preferred_term: Seizures
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:29897170
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There is no genotype-phenotype correlation except for an increased risk
      for epilepsy with 19p13.2 microdeletions.
    explanation: >-
      Confirms seizure risk and genotype-phenotype correlation with deletions.
- category: Clinical
  name: Scoliosis
  description: >
    Scoliosis and kyphosis are recurrent skeletal features.
  frequency: Occasional
  phenotype_term:
    preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  evidence:
  - reference: PMID:25118028
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other recurrent features include pectus excavatum (40%) and scoliosis (25%).
    explanation: >-
      Reports scoliosis in 25% of patients.
- category: Clinical
  name: Pectus Excavatum
  description: >
    Pectus excavatum is a common skeletal finding.
  frequency: Frequent
  phenotype_term:
    preferred_term: Pectus excavatum
    term:
      id: HP:0000767
      label: Pectus excavatum
  evidence:
  - reference: PMID:25118028
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other recurrent features include pectus excavatum (40%) and scoliosis (25%).
    explanation: >-
      Reports pectus excavatum in 40% of patients.
- category: Clinical
  name: Strabismus
  description: >
    Ocular phenotypes are common, with strabismus being the most frequently
    reported.
  frequency: Frequent
  phenotype_term:
    preferred_term: Strabismus
    term:
      id: HP:0000486
      label: Strabismus
  evidence:
  - reference: PMID:25118028
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Ocular phenotypes are common, including strabismus (65%), nystagmus (25%)
      and optic disc pallor/hypoplasia (25%).
    explanation: >-
      Reports strabismus in 65% of patients.
- category: Clinical
  name: Hypotonia
  description: >
    Neonatal hypotonia and feeding difficulties are reported in approximately 30%
    of patients.
  frequency: Frequent
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: PMID:25118028
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Neonatal feeding difficulties and/or hypotonia have been reported in 30%
      of patients.
    explanation: >-
      Quantifies hypotonia/feeding difficulties at 30% frequency.
- category: Clinical
  name: Advanced Bone Age
  description: >
    Accelerated skeletal maturation with advanced bone age is a recurrent finding.
  frequency: Frequent
  phenotype_term:
    preferred_term: Accelerated skeletal maturation
    term:
      id: HP:0005616
      label: Accelerated skeletal maturation
  evidence:
  - reference: PMID:39083629
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      NFIX-related Malan syndrome (MALNS) is characterized by prenatal and
      postnatal overgrowth, macrocephaly, advanced bone age and/or skeletal
      anomalies
    explanation: >-
      GeneReviews lists advanced bone age as a defining feature.
- category: Clinical
  name: Aortic Root Dilatation
  description: >
    Aortic root dilatation has been reported in multiple patients. Progressive
    aortic dilation and dissection has been reported in one adult patient.
  frequency: Occasional
  phenotype_term:
    preferred_term: Aortic root dilatation
    term:
      id: HP:0002616
      label: Aortic root aneurysm
  evidence:
  - reference: PMID:28584646
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      He developed early-onset thoracic aortic aneurysm and dissection, which
      was a rare complication but deserves particular attention in relatively
      long-lived patients with Sotos-like phenotypes.
    explanation: >-
      First report of aortic dissection in Malan syndrome at age 38.
- category: Clinical
  name: Optic Disc Abnormalities
  description: >
    Optic disc pallor and hypoplasia are observed in approximately 25% of patients.
  frequency: Occasional
  phenotype_term:
    preferred_term: Optic disc pallor
    term:
      id: HP:0000543
      label: Optic disc pallor
  evidence:
  - reference: PMID:25118028
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Ocular phenotypes are common, including strabismus (65%), nystagmus (25%)
      and optic disc pallor/hypoplasia (25%).
    explanation: >-
      Reports optic disc pallor/hypoplasia in 25% of patients.
- category: Clinical
  name: Delayed Speech and Language Development
  description: >
    Speech and language delays are a prominent feature and are typically among the
    earliest recognized developmental concerns.
  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:25118028
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Developmental delay/learning disability have been reported in all cases
      and are typically moderate.
    explanation: >-
      Confirms developmental delay including speech delays in all cases.
- category: Clinical
  name: Attention Deficit Hyperactivity Disorder
  description: >
    ADHD is a common behavioral comorbidity alongside the characteristic anxious
    profile.
  frequency: Frequent
  phenotype_term:
    preferred_term: Attention deficit hyperactivity disorder
    term:
      id: HP:0007018
      label: Attention deficit hyperactivity disorder
  evidence:
  - reference: PMID:39083629
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      behavioral problems (including a specific anxious profile and
      attention-deficit/hyperactivity disorder [ADHD])
    explanation: >-
      GeneReviews lists ADHD as a characteristic behavioral feature.
- category: Clinical
  name: Downslanted Palpebral Fissures
  description: >
    Downslanting palpebral fissures are part of the characteristic facial gestalt.
  frequency: Very frequent
  phenotype_term:
    preferred_term: Downslanted palpebral fissures
    term:
      id: HP:0000494
      label: Downslanted palpebral fissures
  evidence:
  - reference: PMID:25118028
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There is overlap of the facial phenotype with NSD1-positive Sotos syndrome
      in some cases including a prominent forehead, high anterior hairline,
      downslanting palpebral fissures and prominent chin.
    explanation: >-
      Reports downslanting palpebral fissures as a recurrent facial feature.
- category: Clinical
  name: Constipation
  description: >
    Constipation is a common gastrointestinal complaint requiring management.
  phenotype_term:
    preferred_term: Constipation
    term:
      id: HP:0002019
      label: Constipation
  evidence:
  - reference: PMID:39083629
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Stool softeners, prokinetics, osmotic agents, or laxatives as needed for
      constipation.
    explanation: >-
      GeneReviews recommends management for constipation, indicating it is a
      recognized feature.
genetic:
- name: NFIX
  association: Pathogenic Variants
  notes: >
    Heterozygous pathogenic variants in NFIX cause Malan syndrome. Approximately
    75% of affected individuals have point mutations (missense, nonsense, or
    frameshift) and 25% have whole-gene or partial deletions of 19p13.2.
    Variants are clustered in the N-terminal DNA-binding/dimerization domain
    (exons 2 and 3). Most cases are de novo, with rare familial cases due to
    parental gonadal mosaicism.
  inheritance:
  - name: Autosomal dominant
  evidence:
  - reference: PMID:39083629
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The diagnosis of MALNS is established in a proband with suggestive findings
      and either a heterozygous pathogenic variant in NFIX (~75% of affected
      individuals) OR a heterozygous deletion of 19p13.2 that includes NFIX
      (~25% of affected individuals) identified by molecular genetic testing.
    explanation: >-
      GeneReviews provides authoritative breakdown of variant types.
  - reference: PMID:29897170
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Malan syndrome is caused by deletions or point mutations of NFIX clustered
      mostly in exon 2. There is no genotype-phenotype correlation except for an
      increased risk for epilepsy with 19p13.2 microdeletions.
    explanation: >-
      Confirms mutation spectrum and clustering in exon 2.
  - reference: PMID:38168088
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report a child with clinical features of Malan syndrome who has
      a de novo NFIX intragenic duplication.
    explanation: >-
      Expands mutation spectrum to include intragenic duplications.
  - reference: CGGV:assertion_9313537f-649e-44b9-9a53-b77a9d7e070c-2023-05-30T160000.000Z
    reference_title: "NFIX / Malan overgrowth syndrome (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "NFIX | HGNC:7788 | Malan overgrowth syndrome | MONDO:0013885 | AD | Definitive"
    explanation: ClinGen classifies the NFIX-Malan overgrowth syndrome gene-disease relationship as definitive with autosomal dominant inheritance.
environmental:
- name: De Novo Occurrence
  description: >
    Nearly all cases arise de novo. The disorder is not associated with
    environmental risk factors. Rare familial cases have been attributed to
    parental gonadal or somatic mosaicism.
  evidence:
  - reference: PMID:29897170
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Variants arose de novo, except in one family in which mother was mosaic.
    explanation: >-
      Confirms de novo occurrence with rare mosaicism-related familial cases.
treatments:
- name: Cognitive Behavioral Therapy
  description: >
    CBT may be used to treat anxiety and ADHD. Symptomatic aids such as colored
    glasses and low voice tone may reduce anxiety outbursts.
  treatment_term:
    preferred_term: cognitive behavioral therapy
    term:
      id: MAXO:0000883
      label: cognitive behavior therapy
  evidence:
  - reference: PMID:39083629
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cognitive behavioral therapy (CBT) may be used to treat anxiety and ADHD.
      Symptomatic aids (i.e., colored glasses, low voice tone) may reduce anxiety
      outbursts.
    explanation: >-
      GeneReviews recommends CBT for behavioral management.
- name: Developmental Support
  description: >
    Standard treatment for developmental delay and intellectual disability including
    speech therapy, occupational therapy, and educational support.
  treatment_term:
    preferred_term: supportive care
    term:
      id: MAXO:0000950
      label: supportive care
  evidence:
  - reference: PMID:39083629
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Standard treatment for epilepsy, Chari I malformation, developmental
      delay / intellectual disability, scoliosis/kyphosis, pes planus, pectus
      anomalies, refractive error, strabismus, tooth anomalies / malocclusion,
      aortic root dilatation / valvular issues, and cryptorchidism.
    explanation: >-
      GeneReviews recommends standard supportive treatment for developmental
      and skeletal features.
- name: Antiepileptic Medication
  description: >
    Standard treatment for seizures and epilepsy in affected individuals.
  treatment_term:
    preferred_term: antiepileptic drug therapy
    term:
      id: MAXO:0000167
      label: anticonvulsant agent therapy
- name: Cardiovascular Surveillance
  description: >
    Annual cardiology follow-up is recommended given the risk of aortic root
    dilatation.
  treatment_term:
    preferred_term: echocardiography
    term:
      id: MAXO:0010203
      label: echocardiography
  evidence:
  - reference: PMID:39083629
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      If the baseline cardiovascular evaluation is normal, consider annual
      cardiology follow up; limited data on aortic root progression is available
      for adults.
    explanation: >-
      GeneReviews recommends cardiovascular surveillance.
datasets:
references:
- reference: PMID:39083629
  title: "NFIX-Related Malan Syndrome."
  tags:
  - GeneReviews
  findings: []

📚

References & Deep Research

References

PMID:39083629

NFIX-Related Malan Syndrome.

No top-level findings curated for this source.

Deep Research

Falcon ▸

Disease Pathophysiology Research Template

Edison Scientific Literature 50 citations 2026-03-28T00:51:59.375753

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

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

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

Disease Pathophysiology Research Template

Target Disease

Disease Name: Malan Syndrome
MONDO ID: (if available)
Category: Mendelian

Research Objectives

Please provide a comprehensive research report on the pathophysiology of Malan Syndrome. Focus on the molecular and cellular mechanisms underlying disease progression.

Required Information

1. Core Pathophysiology

What are the primary pathophysiological mechanisms?
What molecular pathways are dysregulated?
What cellular processes are affected?

2. Key Molecular Players

Genes/Proteins: Which genes are causally involved or implicated?
Chemical Entities: What metabolites, drugs, or small molecules are relevant?
Cell Types: Which cell types are primarily affected?
Anatomical Locations: Which tissues/organs are involved?

3. Biological Processes (for GO annotation)

What biological processes (GO terms) are disrupted?
Consider: signaling pathways, metabolic processes, cellular responses, transport, etc.

4. Cellular Components

Where in the cell do key processes occur?
Consider: organelles, membrane compartments, extracellular space, etc.

5. Disease Progression

What is the sequence of events from initial trigger to clinical manifestation?
Are there distinct stages or phases?

6. Phenotypic Manifestations

What are the key clinical phenotypes?
How do they relate to the underlying mechanisms?

Citation Requirements

Cite primary literature (PMID preferred) for all mechanistic claims
Prioritize recent reviews and landmark papers
Include direct quotes where possible to support key statements

Output Format

Structure your response as a narrative that could be used to populate a disease knowledge base entry with: - Pathophysiology description - Gene/protein annotations with ontology terms (HGNC, GO) - Phenotype associations (HP terms) - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Evidence items with PMIDs

Comprehensive Research Report: Malan Syndrome (Malan overgrowth syndrome)

Disease identifiers and definition

Malan syndrome (also referred to historically as “Sotos syndrome 2”) is an ultra-rare, autosomal dominant overgrowth–neurodevelopmental disorder caused by heterozygous loss of function of NFIX (HGNC:7892; “nuclear factor I X”). (priolo2024nfixrelatedmalansyndrome pages 19-21, priolo2024nfixrelatedmalansyndromeb pages 19-21, priolo2024nfixrelatedmalansyndromea pages 19-21)

MONDO ID: MONDO:0013885 (“Malan overgrowth syndrome”; OpenTargets association evidence). (makker2024apatientcase pages 12-13)
OMIM/MIM: 614753 (Malan syndrome), as cited in the 2024 AJMG paper describing Malan syndrome mechanisms and variant classes. (zhao2024novelmolecularmechanism pages 3-5)

Executive pathophysiology summary (current understanding)

The core disease mechanism is NFIX haploinsufficiency, typically resulting from nonsense/frameshift/splice variants that introduce premature termination codons and are predicted to undergo nonsense-mediated decay (NMD), or from 19p13.2 microdeletions that remove NFIX; pathogenic missense variants cluster in NFIX’s DNA-binding/dimerization domain and are predicted to impair DNA binding and transcriptional regulation. (priolo2024nfixrelatedmalansyndromeb pages 19-21, priolo2024nfixrelatedmalansyndrome pages 21-23, priolo2024nfixrelatedmalansyndrome pages 7-9)

At the molecular/cellular level, reduced functional NFIX disrupts transcriptional programs controlling (i) neural stem/progenitor proliferation vs differentiation timing, (ii) intermediate progenitor production, and (iii) glial lineage specification/maturation (astrocyte maturation vs oligodendrogenesis)—providing a mechanistic route from altered neurodevelopment to megalencephaly/macrocephaly, abnormal brain connectivity, and intellectual disability/behavioral phenotypes. (piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 5-7, piper2019nuclearfactorone pages 1-2, oishi2019heterozygosityfornuclear pages 1-2)

1) Core pathophysiology

Primary pathophysiological mechanisms

A. NFIX loss-of-function via NMD and/or impaired DNA binding NFIX encodes an NFI-family transcription factor that binds a palindromic DNA motif as homo-/heterodimers and has an N-terminal DNA-binding/dimerization domain and a C-terminal transactivation/repression domain. Malan syndrome-associated variants largely map to the DNA-binding/dimerization domain, with many truncating variants predicted to trigger NMD (haploinsufficiency) and missense variants predicted to impair DNA binding. (priolo2024nfixrelatedmalansyndrome pages 19-21, priolo2024nfixrelatedmalansyndromea pages 19-21, priolo2024nfixrelatedmalansyndrome pages 21-23)

B. Neurodevelopmental dysregulation of progenitor dynamics and lineage choice In brain development, NFIX promotes differentiation of neural stem/progenitor cells and influences lineage outputs; NFIX loss delays differentiation of radial glia/neural stem cells and is associated with brain overgrowth (megalencephaly). (piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 5-7)

Mechanistically, NFIX supports intermediate progenitor generation by transcriptionally activating inscuteable (Insc/INSC), which affects apical–basal spindle orientation and intermediate progenitor formation. (piper2019nuclearfactorone pages 3-5)

C. Glial maturation defects and altered gliogenesis NFIX regulates astrocyte gene-expression programs (e.g., astrocyte marker GFAP) and restrains oligodendrogenic programs; NFIX loss is associated with a shift toward oligodendrogenesis in neural stem/progenitor contexts. (piper2019nuclearfactorone pages 5-7, kooblall2024identificationofcellular pages 2-3, piper2019nuclearfactorone pages 1-2)

Dysregulated molecular pathways (evidence-grounded)

The evidence base supports transcriptional dysregulation affecting: - Neurogenesis / intermediate progenitor generation (INSC target). (piper2019nuclearfactorone pages 3-5) - Cell-cycle progression control in neural progenitors (NFIX repression of BBX; BBX promotes G1→S progression). (kooblall2024identificationofcellular pages 2-3) - Astrocyte differentiation and intermediate filament biology (NFIX activation of GFAP). (piper2019nuclearfactorone pages 5-7, kooblall2024identificationofcellular pages 2-3) - Retinoic-acid handling / retinoid-binding biology via CRABP2, identified as a direct NFIX-regulated gene (promoter regulation confirmed by luciferase assay in a mouse/MEF-based systems study). (kooblall2024identificationofcellular pages 2-3)

2) Key molecular players

Genes / proteins

NFIX (HGNC:7892): causal gene; transcription factor; dosage-sensitive. (priolo2024nfixrelatedmalansyndromeb pages 19-21, makker2024apatientcase pages 12-13)
INSC: NFIX activates Insc to promote intermediate progenitor generation. (piper2019nuclearfactorone pages 3-5)
GFAP: NFIX binds/activates GFAP promoter in astrocytes; links NFIX to astrocyte maturation. (piper2019nuclearfactorone pages 5-7, kooblall2024identificationofcellular pages 2-3)
BBX (Bobby Sox): NFIX binds a BBX enhancer to suppress BBX transcription in neural progenitors (cell-cycle implications). (kooblall2024identificationofcellular pages 2-3)
CRABP2 and VCAM1: identified as misregulated downstream genes in NFIX-related skeletal dysplasia models; NFIX directly regulates CRABP2 promoter activity. (kooblall2024identificationofcellular pages 2-3)

Variant mechanism nuance (allelic series context): Malan syndrome is typically haploinsufficiency, while Marshall–Smith syndrome involves truncating variants that may escape NMD and act via a distinct mechanism; recent Malan syndrome molecular work explicitly frames this distinction. (zhao2024novelmolecularmechanism pages 3-5, priolo2024nfixrelatedmalansyndrome pages 7-9)

Chemical entities (metabolites/drugs/small molecules)

Retinoic acid (CHEBI:15367) is mechanistically implicated through NFIX regulation of CRABP2 (cellular retinoic acid binding protein 2), which modulates retinoid biology; this identifies retinoid-handling pathways as a potential mechanistic node for skeletal phenotypes and suggests potential druggability concepts (exploratory). (kooblall2024identificationofcellular pages 2-3)

No established disease-specific pharmacotherapy for Malan syndrome was identified in the retrieved 2023–2024 clinical literature; discussions of future therapeutics remain exploratory. (makker2024apatientcase pages 12-13)

Cell types primarily affected (CL terms; evidence-driven)

Key cell types implicated by expression/function evidence include: - Neural stem cells / neural progenitor cells (CL:0000047 / CL:0011020), including radial glia. (piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 1-2) - Intermediate neural progenitors (intermediate progenitor cells; CL term varies by ontology release) via INSC regulation. (piper2019nuclearfactorone pages 3-5) - Astrocyte lineage cells (CL:0000127) and astrocyte maturation programs (GFAP regulation). (piper2019nuclearfactorone pages 5-7, kooblall2024identificationofcellular pages 2-3) - Oligodendrocyte lineage cells (CL:0000128) (NFIX restrains oligodendrogenic bias). (piper2019nuclearfactorone pages 5-7, piper2019nuclearfactorone pages 1-2) - Ependymal cells (CL:0000065) (ependymal structure defects described in NFIX loss). (piper2019nuclearfactorone pages 1-2)

Anatomical locations / tissues (UBERON terms; evidence-driven)

Brain (UBERON:0000955) with prominent involvement of neocortex, hippocampus, ventricular/SVZ regions, and commissural tracts. (piper2019nuclearfactorone pages 1-2, oishi2019heterozygosityfornuclear pages 3-4)
Corpus callosum (UBERON:0001876) and other commissures (microstructure/tract density abnormalities in Nfix+/−). (oishi2019heterozygosityfornuclear pages 1-2, oishi2019heterozygosityfornuclear pages 7-9, oishi2019heterozygosityfornuclear pages 3-4)
Eye / optic nerve (UBERON:0000970 / UBERON:0000987) (optic nerve hypoplasia/atrophy and other ophthalmologic complications are common). (priolo2024nfixrelatedmalansyndromeb pages 5-7, makker2024apatientcase pages 11-12)
Skeletal system and growth plate cartilage (e.g., UBERON:0000982; UBERON:0001972): NFIX expression in skeletal primordia and growth plate chondrocytes in mouse; clinical skeletal dysplasia features. (malan2010distincteffectsof pages 4-5, priolo2024nfixrelatedmalansyndromeb pages 5-7)

3) Biological processes disrupted (GO-style annotations)

Evidence-supported disrupted processes suitable for GO mapping include: - Regulation of transcription by RNA polymerase II / sequence-specific DNA binding transcription factor activity (NFIX core function). (priolo2024nfixrelatedmalansyndrome pages 19-21, priolo2024nfixrelatedmalansyndromeb pages 19-21) - Neurogenesis and neural stem cell differentiation (delayed differentiation; intermediate progenitor generation; hippocampal neurogenesis effects). (piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 5-7) - Gliogenesis / astrocyte differentiation (GFAP regulation; later-stage astrocyte maturation). (piper2019nuclearfactorone pages 5-7, kooblall2024identificationofcellular pages 2-3) - Oligodendrocyte differentiation / fate specification (bias toward oligodendrogenesis with NFIX loss). (piper2019nuclearfactorone pages 5-7, piper2019nuclearfactorone pages 1-2) - Cell cycle regulation in progenitors (BBX repression; BBX promotes G1→S). (kooblall2024identificationofcellular pages 2-3) - Retinoid metabolic/transport processes (CRABP2 regulation; retinoic-acid binding pathway connection). (kooblall2024identificationofcellular pages 2-3)

4) Cellular components (where key processes occur)

Key cellular locations/components implied by mechanism: - Nucleus (GO:0005634): NFIX DNA-binding transcriptional regulation. (priolo2024nfixrelatedmalansyndrome pages 19-21, priolo2024nfixrelatedmalansyndromeb pages 19-21) - Chromatin / enhancers: NFI factors preferentially bind highly expressed genes and associate with active chromatin marks including distal binding sites (enhancer-like regulation). (piper2019nuclearfactorone pages 9-10)

5) Disease progression (sequence of events)

Germline heterozygous NFIX loss-of-function (de novo in most cases) → reduced NFIX dosage and impaired transcriptional regulation; truncating variants commonly act via NMD. (priolo2024nfixrelatedmalansyndromeb pages 19-21, priolo2024nfixrelatedmalansyndrome pages 21-23)
Developmental dysregulation of neural progenitor programs → prolonged progenitor self-renewal and delayed differentiation, altered intermediate progenitor generation (INSC), and altered gliogenesis (astrocyte maturation programs such as GFAP; oligodendrogenesis bias). (piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 5-7, piper2019nuclearfactorone pages 1-2)
Systems-level brain phenotypes → megalencephaly/macrocephaly, altered commissural tract microstructure/connectomics, and downstream cognitive/behavioral phenotypes, supported by Nfix+/− mouse model data. (oishi2019heterozygosityfornuclear pages 1-2, oishi2019heterozygosityfornuclear pages 7-9, oishi2019heterozygosityfornuclear pages 3-4)
Multisystem manifestations (ocular, musculoskeletal, neurologic, psychobehavioral) evolve across childhood into adulthood; adult natural history demonstrates high rates of ongoing psychobehavioral, musculoskeletal, and vision complications. (macchiaiolo2022adeepphenotyping pages 1-2, makker2024apatientcase pages 11-12)

6) Phenotypic manifestations and mechanistic links

High-confidence core phenotypes (with statistics)

From large compiled cohorts (≥100 individuals), key frequencies include macrocephaly 100%, developmental delay/intellectual disability 100%, and distinctive facial features 100%. (priolo2024nfixrelatedmalansyndromeb pages 3-5, priolo2024nfixrelatedmalansyndrome media 09fd8188)

From the same frequency summaries: postnatal height >2 SD was reported at ~56%; hypotonia ~65%; epilepsy/EEG anomalies ~63%; autonomic signs ~25%; and ocular issues are frequent (refractive errors ~75%, strabismus ~63%, optic nerve hypoplasia ~25%), while major cardiac anomalies are uncommon (~4%). (priolo2024nfixrelatedmalansyndromeb pages 5-7, priolo2024nfixrelatedmalansyndromea pages 5-7, priolo2024nfixrelatedmalansyndrome pages 3-5, priolo2024nfixrelatedmalansyndrome media 09fd8188)

A clinical “expert summary” statement in the 2024 chapter emphasizes intellectual disability severity: “normal intellectual development has never been reported in MALNS and mild ID is rarely observed.” (priolo2024nfixrelatedmalansyndromea pages 9-11)

Adult natural history (2024; real-world progression)

A 2024 adult survey (n=28) characterized adulthood as multisystemic, with psychobehavioral comorbidities 96%, musculoskeletal involvement 96%, vision impairment 96%, and neurological complications 86%. (makker2024apatientcase pages 11-12)

Mechanistic links

Macrocephaly/megalencephaly is consistent with experimental evidence that NFIX influences neural progenitor self-renewal vs differentiation and developmental timing in the brain. (piper2019nuclearfactorone pages 5-7, piper2019nuclearfactorone pages 1-2)
Cognitive/behavioral phenotypes are consistent with hippocampal neurogenesis defects and connectome/commissural tract abnormalities reported in Nfix+/− models. (piper2019nuclearfactorone pages 5-7, oishi2019heterozygosityfornuclear pages 7-9)
Ocular phenotypes (optic nerve hypoplasia/atrophy) likely reflect developmental transcriptional dysregulation, though direct NFIX→optic-nerve mechanistic studies were not retrieved in this search; clinical evidence supports frequent ophthalmologic involvement. (priolo2024nfixrelatedmalansyndromeb pages 5-7, makker2024apatientcase pages 11-12)

Recent developments and latest research (prioritizing 2023–2024)

2024: Novel molecular mechanism—NFIX intragenic duplication with RNA-seq confirmation

Zhao et al. (American Journal of Medical Genetics Part A; Jan 2024; https://doi.org/10.1002/ajmg.a.63516) reported the first Malan syndrome case caused by an intragenic NFIX tandem duplication (exons 6–7) and used exon-level microarray plus RNA-seq to show ~50% NFIX transcript levels and absence of the mutant transcript, supporting NMD-mediated haploinsufficiency. (zhao2024novelmolecularmechanism pages 3-5)

Clinical implementation implication: small intragenic CNVs can be missed by standard tests, motivating genome/exon-level CNV approaches and RNA confirmation in unresolved cases. (zhao2024novelmolecularmechanism pages 3-5)

2024: Downstream targets and potential druggability concepts (CRABP2/VCAM1)

Kooblall et al. (JBMR Plus; May 2024; https://doi.org/10.1093/jbmrpl/ziae060) used RNA-seq/proteomics across Nfix mouse models and patient fibroblasts to identify misregulated genes and validated CRABP2 as a direct NFIX-regulated gene (promoter regulation), suggesting downstream pathway nodes (retinoid biology) that might be leveraged therapeutically in NFIX-related skeletal dysplasias (conceptual at present). (kooblall2024identificationofcellular pages 2-3)

2024: Adult natural history and standards-of-care needs

Huynh et al. (Orphanet Journal of Rare Diseases; Jul 2024; https://doi.org/10.1186/s13023-024-03288-6) surveyed 28 adults and documented high prevalence of psychobehavioral, musculoskeletal, vision, and neurologic complications, emphasizing the need to extend management guidance beyond pediatrics. (makker2024apatientcase pages 11-12)

2024: Longitudinal clinical management case (15-year follow-up)

Makker et al. (Journal of Clinical Medicine; Nov 2024; https://doi.org/10.3390/jcm13216575) presented a long-term follow-up case and reinforced the centrality of NFIX dosage sensitivity (“haploinsufficiency”) to multisystem neurodevelopmental disease; the paper also discussed exploratory RNA-targeted strategies to increase NFIX translation rather than traditional overexpression approaches, due to dose sensitivity. (makker2024apatientcase pages 12-13)

Current applications and real-world implementations

Diagnostics

Primary application is genetic diagnosis using exome/genome sequencing and copy-number variant detection for 19p13.2 deletions and intragenic NFIX variants; exon-level CNV and RNA analyses can be important in atypical/negative cases. (zhao2024novelmolecularmechanism pages 3-5, priolo2024nfixrelatedmalansyndrome pages 7-9)

Multidisciplinary surveillance and management

A single-center deep phenotyping/surveillance program (Orphanet J Rare Dis; Jun 2022; https://doi.org/10.1186/s13023-022-02384-9) proposed a minimal dataset for follow-up and highlighted complications requiring active monitoring, including childhood fracture risk, neurovegetative symptoms, noise sensitivity, and Chiari I malformation. (macchiaiolo2022adeepphenotyping pages 1-2)

Expert opinions and analysis (authoritative sources)

The 2024 NFIX-related Malan syndrome chapter provides a consensus-style synthesis of variant mechanisms (NMD-driven haploinsufficiency; DNA-binding domain missense hotspots) and consolidates cohort-level phenotype frequencies. (priolo2024nfixrelatedmalansyndrome pages 19-21, priolo2024nfixrelatedmalansyndromeb pages 5-7)
A high-impact cell biology review (Trends in Cell Biology; Jan 2019; https://doi.org/10.1016/j.tcb.2018.09.003) provides mechanistic framing for NFIX’s context-dependent roles in neural stem/progenitor biology, astrocyte maturation, and lineage specification, explaining how dosage changes can alter neurodevelopmental trajectories relevant to Malan syndrome. (piper2019nuclearfactorone pages 5-7, piper2019nuclearfactorone pages 1-2)

Key statistics and data (recent cohorts)

Macrocephaly: 100%; ≥77% of adults have head circumference >2 SD. (priolo2024nfixrelatedmalansyndrome pages 3-5, priolo2024nfixrelatedmalansyndromeb pages 3-5, priolo2024nfixrelatedmalansyndrome media 09fd8188)
Developmental delay / intellectual disability: 100%; typically moderate to severe. (priolo2024nfixrelatedmalansyndrome pages 3-5, priolo2024nfixrelatedmalansyndromeb pages 3-5, priolo2024nfixrelatedmalansyndromea pages 9-11)
Postnatal height >2 SD: ~56%. (priolo2024nfixrelatedmalansyndrome pages 3-5, priolo2024nfixrelatedmalansyndromeb pages 3-5)
Hypotonia: ~65%. (priolo2024nfixrelatedmalansyndrome pages 3-5, priolo2024nfixrelatedmalansyndromeb pages 3-5)
Epilepsy/EEG anomalies: ~63% in one deep-phenotyping cohort; risk may be higher with contiguous deletions including nearby genes. (priolo2024nfixrelatedmalansyndrome pages 3-5, priolo2024nfixrelatedmalansyndrome pages 7-9)
Adult complications (n=28): psychobehavioral comorbidity 96%, musculoskeletal involvement 96%, vision impairment 96%, neurological complications 86%. (makker2024apatientcase pages 11-12)

Knowledge-base–ready annotation block

Pathophysiology description (narrative)

Malan syndrome is caused by heterozygous loss-of-function of NFIX, most commonly via truncating variants that are predicted to trigger NMD and create NFIX haploinsufficiency, or via missense variants in the DNA-binding/dimerization domain that impair DNA binding. Reduced NFIX dosage disrupts transcriptional regulation of developmental programs governing neural stem/progenitor differentiation timing, intermediate progenitor generation (via INSC), cell-cycle exit (via repression of BBX), and glial lineage specification and astrocyte maturation (via GFAP and broader astrocyte programs), leading to megalencephaly/macrocephaly and downstream neurodevelopmental deficits; animal models further link NFIX haploinsufficiency to altered commissural tract microstructure/connectome organization and learning/social behavior abnormalities. (priolo2024nfixrelatedmalansyndromeb pages 19-21, piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 5-7, kooblall2024identificationofcellular pages 2-3, oishi2019heterozygosityfornuclear pages 3-4)

Gene/protein annotations

NFIX (HGNC:7892): sequence-specific DNA-binding transcription factor; haploinsufficiency mechanism via NMD for many truncating alleles. (priolo2024nfixrelatedmalansyndromeb pages 19-21, priolo2024nfixrelatedmalansyndrome pages 21-23)
Downstream targets (evidence): INSC, GFAP, BBX, CRABP2, VCAM1. (piper2019nuclearfactorone pages 3-5, kooblall2024identificationofcellular pages 2-3)

Phenotype associations (HPO examples; evidence-supported)

Macrocephaly (HP:0000256). (priolo2024nfixrelatedmalansyndrome pages 3-5, priolo2024nfixrelatedmalansyndrome media 09fd8188)
Intellectual disability (HP:0001249) / global developmental delay (HP:0001263). (priolo2024nfixrelatedmalansyndrome pages 3-5, priolo2024nfixrelatedmalansyndromea pages 9-11)
Hypotonia (HP:0001252). (priolo2024nfixrelatedmalansyndrome pages 3-5)
Strabismus (HP:0000486) / refractive error (HP:0000517) / optic nerve hypoplasia (HP:0000609). (priolo2024nfixrelatedmalansyndromeb pages 5-7, makker2024apatientcase pages 11-12)
Seizures (HP:0001250) / abnormal EEG. (priolo2024nfixrelatedmalansyndrome pages 3-5)
Scoliosis (HP:0002650) / skeletal anomalies. (priolo2024nfixrelatedmalansyndromeb pages 5-7, makker2024apatientcase pages 11-12)
Chiari malformation type I (HP:0007099). (macchiaiolo2022adeepphenotyping pages 1-2, makker2024apatientcase pages 11-12)

Cell type involvement (CL examples)

Neural stem/progenitor cells and radial glia; intermediate progenitors; astrocyte lineage; oligodendrocyte lineage; ependymal cells; mature cortical neurons. (piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 1-2, piper2019nuclearfactorone pages 2-3)

Anatomical locations (UBERON examples)

Cerebral cortex/neocortex; hippocampus/dentate gyrus; corpus callosum/anterior commissure; optic nerve; skeletal primordia/growth plate. (oishi2019heterozygosityfornuclear pages 3-4, oishi2019heterozygosityfornuclear pages 7-9, malan2010distincteffectsof pages 4-5)

Chemical entities (CHEBI examples)

Retinoic acid (CHEBI:15367) via CRABP2 pathway linkage (mechanistic node; not established as therapy). (kooblall2024identificationofcellular pages 2-3)

Evidence table (compact)

The following table compiles genetics, mechanisms, targets, phenotypes, statistics, and applications with traceable citations.

Category	Key points	Representative evidence & statistics	Key sources with year	DOI/URL
Genetics	Malan syndrome / Malan overgrowth syndrome is an autosomal dominant NFIX-related disorder caused by heterozygous loss-of-function variants or 19p13.2 deletions; MONDO:0013885. Mechanistically, disease is primarily due to NFIX haploinsufficiency, usually from truncating/splice variants predicted to trigger nonsense-mediated decay (NMD); missense variants in the DNA-binding/dimerization domain likely impair DNA binding. Most cases are de novo. Distinct from Marshall-Smith syndrome, where 3′ truncating variants may escape NMD and act differently. (priolo2024nfixrelatedmalansyndrome pages 19-21, priolo2024nfixrelatedmalansyndromeb pages 19-21, priolo2024nfixrelatedmalansyndromea pages 19-21, priolo2024nfixrelatedmalansyndrome pages 7-9)	At least ~25% of affected individuals have 19p13.2 deletions including NFIX; larger deletions can include CACNA1A and raise seizure risk. Historical review of 20 published patients found 14 deletions, 3 truncating variants, and 3 missense/in-frame variants. (klaassens2015malansyndromesotoslike pages 4-5, priolo2024nfixrelatedmalansyndrome pages 7-9)	Malan et al., 2010; Klaassens et al., 2015; Priolo, 2024; Zhao et al., 2024	https://doi.org/10.1016/j.ajhg.2010.07.001; https://doi.org/10.1038/ejhg.2014.162; https://doi.org/10.1002/ajmg.a.63516
Mechanism	NFIX is a dose-sensitive transcription factor of the NFI family that binds a palindromic DNA motif as homo-/heterodimers. Haploinsufficiency disrupts developmental transcriptional programs controlling neural progenitor cell-cycle exit, intermediate progenitor generation, gliogenesis, astrocyte maturation, and repression of oligodendroglial fate; this provides a mechanistic basis for megalencephaly, neurodevelopmental disability, and multisystem developmental abnormalities. (priolo2024nfixrelatedmalansyndromeb pages 19-21, piper2019nuclearfactorone pages 9-10, piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 5-7, piper2019nuclearfactorone pages 1-2)	Primary developmental mechanism: delayed differentiation of radial glia/NSCs, reduced neuronal/glial differentiation late in embryogenesis, prolonged progenitor self-renewal, and altered lineage choice toward oligodendrogenesis. NFIX also regulates stem-cell proliferation, quiescence, and differentiation across tissues. (makker2024apatientcase pages 12-13, piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 5-7, piper2019nuclearfactorone pages 1-2)	Piper et al., 2019; Oishi et al., 2019; Priolo, 2024; Makker et al., 2024	https://doi.org/10.1016/j.tcb.2018.09.003; https://doi.org/10.1016/j.ebiom.2018.11.044; https://doi.org/10.3390/jcm13216575
Downstream targets	Validated or reported NFIX downstream targets include INSC (intermediate progenitor generation), GFAP (astrocyte differentiation), BBX/Bobby Sox (cell-cycle progression repression in neural progenitors), and more recently CRABP2 and VCAM1 in fibroblast/MEF models. NFIX can act as activator or repressor in a context-dependent manner. (piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 5-7, kooblall2024identificationofcellular pages 2-3)	INSC activation links NFIX to spindle orientation and intermediate progenitor production; GFAP activation links NFIX to astrocyte maturation; BBX repression links NFIX to G1→S control and progenitor exit. Multi-omics in 2024 identified 191 misregulated transcripts and 815 misregulated proteins in Nfix mutant MEFs, with CRABP2 directly regulated at promoter level and altered in 60%–100% of MSS fibroblasts. (piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 5-7, kooblall2024identificationofcellular pages 2-3)	Piper et al., 2019; Kooblall et al., 2024	https://doi.org/10.1016/j.tcb.2018.09.003; https://doi.org/10.1093/jbmrpl/ziae060
Cell types & tissues	Key affected cell types include radial glia / neural stem cells, intermediate progenitors, astrocyte-lineage cells, oligodendrocyte-lineage cells, ependymal cells, neuroblasts, mature cortical neurons, and fibroblasts/MEFs used for mechanistic studies. Principal tissues are developing brain (neocortex, hippocampus, SVZ/RMS, cerebellum), optic system, skeleton/bone, and connective/musculoskeletal tissues. (piper2019nuclearfactorone pages 9-10, piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 5-7, piper2019nuclearfactorone pages 1-2, piper2019nuclearfactorone pages 2-3, malan2010distincteffectsof pages 4-5)	NFIX expression is reported in embryonic germinal zones, radial glia, intermediate progenitors, cortical plate, dentate gyrus, ventricular zones, cerebellar granule progenitors, ependymal cells, and about half of mature neocortical neurons. During development, skeletal primordia and growth-plate chondrocytes also express NFIX. (piper2019nuclearfactorone pages 3-5, piper2019nuclearfactorone pages 1-2, piper2019nuclearfactorone pages 2-3, malan2010distincteffectsof pages 4-5)	Piper et al., 2019; Malan et al., 2010; Kooblall et al., 2024	https://doi.org/10.1016/j.tcb.2018.09.003; https://doi.org/10.1016/j.ajhg.2010.07.001; https://doi.org/10.1093/jbmrpl/ziae060
Mouse model evidence	Nfix+/− mice model NFIX haploinsufficiency and reproduce key Malan syndrome features including megalencephaly, abnormal forebrain commissures/connectivity, and learning/social deficits. Nfix−/− mice show more severe developmental phenotypes including megalencephaly, delayed cortical differentiation, altered oligodendrogenesis, skeletal defects, failure to thrive, and early death. (oishi2019heterozygosityfornuclear pages 1-2, piper2019nuclearfactorone pages 5-7, piper2019nuclearfactorone pages 3-5, oishi2019heterozygosityfornuclear pages 7-9, piper2019nuclearfactorone pages 1-2, malan2010distincteffectsof pages 4-5)	In adult Nfix+/− mice, total brain volume was 532.34 ± 22.61 vs 457.75 ± 20.63 in WT (p<0.0001), with 19/20 brain subregions enlarged; largest increases: corpus callosum 25.46%, neocortex 23.11%, anterior commissure 17.52%. Diffusion MRI showed reduced tract density and abnormal commissural microstructure; behavioral testing showed impaired spatial memory and abnormal sociability. (oishi2019heterozygosityfornuclear pages 1-2, oishi2019heterozygosityfornuclear pages 7-9, oishi2019heterozygosityfornuclear pages 3-4)	Oishi et al., 2019; Piper et al., 2019; Malan et al., 2010	https://doi.org/10.1016/j.ebiom.2018.11.044; https://doi.org/10.1016/j.tcb.2018.09.003; https://doi.org/10.1016/j.ajhg.2010.07.001
Clinical frequencies	Core phenotype is consistent across cohorts: distinctive facial features, developmental delay/intellectual disability, and macrocephaly are essentially universal; overgrowth is common but variable. Vision, musculoskeletal, behavioral, and neurologic complications are frequent. (priolo2024nfixrelatedmalansyndromeb pages 5-7, priolo2024nfixrelatedmalansyndromea pages 5-7, priolo2024nfixrelatedmalansyndrome pages 5-7, priolo2024nfixrelatedmalansyndrome pages 3-5, priolo2024nfixrelatedmalansyndromeb pages 3-5, priolo2024nfixrelatedmalansyndrome media 09fd8188)	Reported frequencies include: distinctive facial features 100%; macrocephaly 100% with ≥77% of adults >2 SD; developmental delay/ID 100%; postnatal height >2 SD 56%; hypotonia ~65%; neurobehavioral features ~67%; epilepsy/EEG anomalies 63%; autonomic signs 25%; slender habitus 100% (16/16); advanced bone age 76%; abnormal spine curvature 75%; pes planus 69%; refractive error 75%; strabismus 63%; optic nerve hypoplasia 25%; cardiac anomalies uncommon (~4%). Adult survey (n=28): psychobehavioral 96%, musculoskeletal 96%, vision impairment 96%, neurologic complications 86%; anxiety 79%, hypotonia 75%, movement difficulty 75%, scoliosis 64%, constipation 54%, optic atrophy 32%. (priolo2024nfixrelatedmalansyndromeb pages 5-7, priolo2024nfixrelatedmalansyndromea pages 5-7, priolo2024nfixrelatedmalansyndrome pages 5-7, makker2024apatientcase pages 11-12, priolo2024nfixrelatedmalansyndrome pages 3-5, priolo2024nfixrelatedmalansyndromeb pages 3-5)	Macchiaiolo et al., 2022; Huynh et al., 2024; Priolo, 2024; Makker et al., 2024	https://doi.org/10.1186/s13023-022-02384-9; https://doi.org/10.1186/s13023-024-03288-6; https://doi.org/10.3390/jcm13216575
Recent developments	2024 studies materially advanced mechanism and natural history. A novel intragenic NFIX duplication (exons 6–7) was shown by GS/exon-array/RNA-seq to cause haploinsufficiency via NMD; adult natural-history data refined syndrome progression; and multi-omics identified CRABP2 as a direct NFIX target with therapeutic relevance. (zhao2024novelmolecularmechanism pages 3-5, makker2024apatientcase pages 12-13)	The 2024 AJMG case showed ~50% NFIX transcript level with absence of mutant transcript in fibroblasts, supporting NMD-mediated haploinsufficiency. The 2024 adult survey enrolled 28 adults and highlighted evolving burden of psychobehavioral, musculoskeletal, vision, and neurologic complications. The 2024 longitudinal case emphasized developmental gains with early intervention and discussed future RNA-based therapeutic concepts. (zhao2024novelmolecularmechanism pages 3-5, makker2024apatientcase pages 12-13, makker2024apatientcase pages 11-12)	Zhao et al., 2024; Huynh et al., 2024; Makker et al., 2024; Kooblall et al., 2024	https://doi.org/10.1002/ajmg.a.63516; https://doi.org/10.1186/s13023-024-03288-6; https://doi.org/10.3390/jcm13216575; https://doi.org/10.1093/jbmrpl/ziae060
Applications & management	Real-world implementation is currently centered on molecular diagnosis and multidisciplinary surveillance. Evidence supports using exome/genome sequencing plus CNV-sensitive methods and, when needed, RNA studies because small intragenic rearrangements may be missed by routine tests. Clinical management focuses on ophthalmologic, neurologic, behavioral, musculoskeletal, and developmental monitoring. (zhao2024novelmolecularmechanism pages 3-5, macchiaiolo2022adeepphenotyping pages 1-2, makker2024apatientcase pages 12-13)	Single-center surveillance proposed a minimal follow-up dataset and identified complications warranting active monitoring, including fractures, neurovegetative symptoms, noise sensitivity, and Chiari I malformation. Adult natural-history work proposed additional adult recommendations. Future therapy discussion is exploratory: because NFIX is dose-sensitive, AAV overexpression may be risky; RNA-targeted approaches such as antisense strategies to increase translation were proposed, but no disease-specific clinical therapies are established. (macchiaiolo2022adeepphenotyping pages 1-2, makker2024apatientcase pages 12-13)	Macchiaiolo et al., 2022; Huynh et al., 2024; Makker et al., 2024; Zhao et al., 2024	https://doi.org/10.1186/s13023-022-02384-9; https://doi.org/10.1186/s13023-024-03288-6; https://doi.org/10.3390/jcm13216575; https://doi.org/10.1002/ajmg.a.63516

Table: This table summarizes the key genetics, mechanisms, downstream targets, model systems, phenotype frequencies, and 2024 developments relevant to Malan syndrome pathophysiology. It is designed as a compact evidence-traceable reference for a disease knowledge base entry.

Key visual evidence

A cohort frequency table for Malan syndrome clinical features is provided in the 2024 chapter (Table 2; cropped), supporting reported frequencies for macrocephaly, developmental delay/ID, hypotonia, epilepsy/EEG anomalies, and ocular/musculoskeletal involvement. (priolo2024nfixrelatedmalansyndrome media 09fd8188, priolo2024nfixrelatedmalansyndrome media c2ca2dc8)

Limitations and gaps

Despite clear evidence for NFIX haploinsufficiency as the proximal cause, the full downstream transcriptional network and tissue-specific target sets in human neurodevelopment remain incompletely mapped, and no disease-specific molecular therapy is yet established in clinical practice; current care is therefore surveillance- and support-focused. (makker2024apatientcase pages 12-13, piper2019nuclearfactorone pages 9-10)

Source URLs and publication dates (selected)

Zhao J et al. Am J Med Genet A (Jan 2024). https://doi.org/10.1002/ajmg.a.63516 (zhao2024novelmolecularmechanism pages 3-5)
Kooblall KG et al. JBMR Plus (May 2024). https://doi.org/10.1093/jbmrpl/ziae060 (kooblall2024identificationofcellular pages 2-3)
Huynh TN et al. Orphanet J Rare Dis (Jul 2024). https://doi.org/10.1186/s13023-024-03288-6 (makker2024apatientcase pages 11-12)
Makker S et al. J Clin Med (Nov 2024). https://doi.org/10.3390/jcm13216575 (makker2024apatientcase pages 12-13)
Piper M et al. Trends Cell Biol (Jan 2019). https://doi.org/10.1016/j.tcb.2018.09.003 (piper2019nuclearfactorone pages 3-5)
Oishi S et al. EBioMedicine (Jan 2019). https://doi.org/10.1016/j.ebiom.2018.11.044 (oishi2019heterozygosityfornuclear pages 3-4)

References

(priolo2024nfixrelatedmalansyndrome pages 19-21): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(priolo2024nfixrelatedmalansyndromeb pages 19-21): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(priolo2024nfixrelatedmalansyndromea pages 19-21): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(makker2024apatientcase pages 12-13): Simran Makker, Bernadine R. Gagnon, Isabella Trew, Vivian Mougios, Anne Hanna, Jessica M. Cale, and Craig S. McIntosh. A patient case of malan syndrome involving 19p13.2 deletion of nfix with longitudinal follow-up and future prospectives. Journal of Clinical Medicine, 13:6575, Nov 2024. URL: https://doi.org/10.3390/jcm13216575, doi:10.3390/jcm13216575. This article has 3 citations.
(zhao2024novelmolecularmechanism pages 3-5): Jian Zhao, Nicola Longo, Robert G. Lewis, Thomas J. Nicholas, Steven E. Boyden, Ashley Andrews, Austin Larson, Pinar Bayrak‐Toydemir, Lorenzo D. Botto, and Rong Mao. Novel molecular mechanism in malan syndrome uncovered through genome sequencing reanalysis, exon‐level array, and rna sequencing. American Journal of Medical Genetics Part A, Jan 2024. URL: https://doi.org/10.1002/ajmg.a.63516, doi:10.1002/ajmg.a.63516. This article has 4 citations.
(priolo2024nfixrelatedmalansyndrome pages 21-23): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(priolo2024nfixrelatedmalansyndrome pages 7-9): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(piper2019nuclearfactorone pages 3-5): Michael Piper, Richard Gronostajski, and Graziella Messina. Nuclear factor one x in development and disease. Trends in cell biology, 29 1:20-30, Jan 2019. URL: https://doi.org/10.1016/j.tcb.2018.09.003, doi:10.1016/j.tcb.2018.09.003. This article has 68 citations and is from a domain leading peer-reviewed journal.
(piper2019nuclearfactorone pages 5-7): Michael Piper, Richard Gronostajski, and Graziella Messina. Nuclear factor one x in development and disease. Trends in cell biology, 29 1:20-30, Jan 2019. URL: https://doi.org/10.1016/j.tcb.2018.09.003, doi:10.1016/j.tcb.2018.09.003. This article has 68 citations and is from a domain leading peer-reviewed journal.
(piper2019nuclearfactorone pages 1-2): Michael Piper, Richard Gronostajski, and Graziella Messina. Nuclear factor one x in development and disease. Trends in cell biology, 29 1:20-30, Jan 2019. URL: https://doi.org/10.1016/j.tcb.2018.09.003, doi:10.1016/j.tcb.2018.09.003. This article has 68 citations and is from a domain leading peer-reviewed journal.
(oishi2019heterozygosityfornuclear pages 1-2): Sabrina Oishi, Danyon Harkins, Nyoman D. Kurniawan, Maria Kasherman, Lachlan Harris, Oressia Zalucki, Richard M. Gronostajski, Thomas H.J. Burne, and Michael Piper. Heterozygosity for nuclear factor one x in mice models features of malan syndrome. EBioMedicine, 39:388-400, Jan 2019. URL: https://doi.org/10.1016/j.ebiom.2018.11.044, doi:10.1016/j.ebiom.2018.11.044. This article has 21 citations and is from a peer-reviewed journal.
(kooblall2024identificationofcellular pages 2-3): Kreepa G Kooblall, Mark Stevenson, Raphael Heilig, Michelle Stewart, Benjamin Wright, Helen Lockstone, David Buck, Roman Fischer, Sara Wells, Kate E Lines, Lydia Teboul, Raoul C Hennekam, and Rajesh V Thakker. Identification of cellular retinoic acid binding protein 2 (crabp2) as downstream target of nuclear factor i/x (nfix): implications for skeletal dysplasia syndromes. JBMR Plus, May 2024. URL: https://doi.org/10.1093/jbmrpl/ziae060, doi:10.1093/jbmrpl/ziae060. This article has 3 citations and is from a peer-reviewed journal.
(oishi2019heterozygosityfornuclear pages 3-4): Sabrina Oishi, Danyon Harkins, Nyoman D. Kurniawan, Maria Kasherman, Lachlan Harris, Oressia Zalucki, Richard M. Gronostajski, Thomas H.J. Burne, and Michael Piper. Heterozygosity for nuclear factor one x in mice models features of malan syndrome. EBioMedicine, 39:388-400, Jan 2019. URL: https://doi.org/10.1016/j.ebiom.2018.11.044, doi:10.1016/j.ebiom.2018.11.044. This article has 21 citations and is from a peer-reviewed journal.
(oishi2019heterozygosityfornuclear pages 7-9): Sabrina Oishi, Danyon Harkins, Nyoman D. Kurniawan, Maria Kasherman, Lachlan Harris, Oressia Zalucki, Richard M. Gronostajski, Thomas H.J. Burne, and Michael Piper. Heterozygosity for nuclear factor one x in mice models features of malan syndrome. EBioMedicine, 39:388-400, Jan 2019. URL: https://doi.org/10.1016/j.ebiom.2018.11.044, doi:10.1016/j.ebiom.2018.11.044. This article has 21 citations and is from a peer-reviewed journal.
(priolo2024nfixrelatedmalansyndromeb pages 5-7): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(makker2024apatientcase pages 11-12): Simran Makker, Bernadine R. Gagnon, Isabella Trew, Vivian Mougios, Anne Hanna, Jessica M. Cale, and Craig S. McIntosh. A patient case of malan syndrome involving 19p13.2 deletion of nfix with longitudinal follow-up and future prospectives. Journal of Clinical Medicine, 13:6575, Nov 2024. URL: https://doi.org/10.3390/jcm13216575, doi:10.3390/jcm13216575. This article has 3 citations.
(malan2010distincteffectsof pages 4-5): Valérie Malan, Diana Rajan, Sophie Thomas, Adam C. Shaw, Hélène Louis dit Picard, Valérie Layet, Marianne Till, Arie van Haeringen, Geert Mortier, Sheela Nampoothiri, Silvija Pušeljić, Laurence Legeai-Mallet, Nigel P. Carter, Michel Vekemans, Arnold Munnich, Raoul C. Hennekam, Laurence Colleaux, and Valérie Cormier-Daire. Distinct effects of allelic nfix mutations on nonsense-mediated mrna decay engender either a sotos-like or a marshall-smith syndrome. American journal of human genetics, 87 2:189-98, Aug 2010. URL: https://doi.org/10.1016/j.ajhg.2010.07.001, doi:10.1016/j.ajhg.2010.07.001. This article has 187 citations and is from a highest quality peer-reviewed journal.
(piper2019nuclearfactorone pages 9-10): Michael Piper, Richard Gronostajski, and Graziella Messina. Nuclear factor one x in development and disease. Trends in cell biology, 29 1:20-30, Jan 2019. URL: https://doi.org/10.1016/j.tcb.2018.09.003, doi:10.1016/j.tcb.2018.09.003. This article has 68 citations and is from a domain leading peer-reviewed journal.
(macchiaiolo2022adeepphenotyping pages 1-2): Marina Macchiaiolo, Filippo M. Panfili, Davide Vecchio, Michaela V. Gonfiantini, Fabiana Cortellessa, Cristina Caciolo, Marcella Zollino, Maria Accadia, Marco Seri, Marcello Chinali, Corrado Mammì, Marco Tartaglia, Andrea Bartuli, Paolo Alfieri, and Manuela Priolo. A deep phenotyping experience: up to date in management and diagnosis of malan syndrome in a single center surveillance report. Orphanet Journal of Rare Diseases, Jun 2022. URL: https://doi.org/10.1186/s13023-022-02384-9, doi:10.1186/s13023-022-02384-9. This article has 25 citations and is from a peer-reviewed journal.
(priolo2024nfixrelatedmalansyndromeb pages 3-5): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(priolo2024nfixrelatedmalansyndrome media 09fd8188): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(priolo2024nfixrelatedmalansyndromea pages 5-7): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(priolo2024nfixrelatedmalansyndrome pages 3-5): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(priolo2024nfixrelatedmalansyndromea pages 9-11): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(piper2019nuclearfactorone pages 2-3): Michael Piper, Richard Gronostajski, and Graziella Messina. Nuclear factor one x in development and disease. Trends in cell biology, 29 1:20-30, Jan 2019. URL: https://doi.org/10.1016/j.tcb.2018.09.003, doi:10.1016/j.tcb.2018.09.003. This article has 68 citations and is from a domain leading peer-reviewed journal.
(klaassens2015malansyndromesotoslike pages 4-5): Merel Klaassens, Deborah Morrogh, Elisabeth M Rosser, Fatima Jaffer, Maaike Vreeburg, Levinus A Bok, Tim Segboer, Martine van Belzen, Ros M Quinlivan, Ajith Kumar, Jane A Hurst, and Richard H Scott. Malan syndrome: sotos-like overgrowth with de novo nfix sequence variants and deletions in six new patients and a review of the literature. European Journal of Human Genetics, 23:610-615, Aug 2015. URL: https://doi.org/10.1038/ejhg.2014.162, doi:10.1038/ejhg.2014.162. This article has 95 citations and is from a domain leading peer-reviewed journal.
(priolo2024nfixrelatedmalansyndrome pages 5-7): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.
(priolo2024nfixrelatedmalansyndrome media c2ca2dc8): M Priolo. Nfix-related malan syndrome. Unknown journal, 2024.

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Phenotypes

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References & Deep Research

References

Deep Research

Disease Pathophysiology Research Template

Target Disease

Research Objectives

Required Information

1. Core Pathophysiology

2. Key Molecular Players

3. Biological Processes (for GO annotation)

4. Cellular Components

5. Disease Progression

6. Phenotypic Manifestations

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Output Format

Comprehensive Research Report: Malan Syndrome (Malan overgrowth syndrome)

Disease identifiers and definition

Executive pathophysiology summary (current understanding)

1) Core pathophysiology

Primary pathophysiological mechanisms

Dysregulated molecular pathways (evidence-grounded)

2) Key molecular players

Genes / proteins

Chemical entities (metabolites/drugs/small molecules)

Cell types primarily affected (CL terms; evidence-driven)

Anatomical locations / tissues (UBERON terms; evidence-driven)

3) Biological processes disrupted (GO-style annotations)

4) Cellular components (where key processes occur)

5) Disease progression (sequence of events)

6) Phenotypic manifestations and mechanistic links

High-confidence core phenotypes (with statistics)

Adult natural history (2024; real-world progression)

Mechanistic links

Recent developments and latest research (prioritizing 2023–2024)

2024: Novel molecular mechanism—NFIX intragenic duplication with RNA-seq confirmation

2024: Downstream targets and potential druggability concepts (CRABP2/VCAM1)

2024: Adult natural history and standards-of-care needs

2024: Longitudinal clinical management case (15-year follow-up)

Current applications and real-world implementations

Diagnostics

Multidisciplinary surveillance and management

Expert opinions and analysis (authoritative sources)

Key statistics and data (recent cohorts)

Knowledge-base–ready annotation block

Pathophysiology description (narrative)

Gene/protein annotations

Phenotype associations (HPO examples; evidence-supported)

Cell type involvement (CL examples)

Anatomical locations (UBERON examples)

Chemical entities (CHEBI examples)

Evidence table (compact)

Key visual evidence

Limitations and gaps

Source URLs and publication dates (selected)