Jacobsen Syndrome

Genetic MONDO:0007838 Pathograph 6 Show in embeddings browser hereditary disease chromosomal disorder

Jacobsen syndrome is a multiple-congenital-anomaly/intellectual-disability contiguous-gene syndrome caused by a partial deletion of the long arm of chromosome 11 (distal 11q), extending from a breakpoint at or telomeric to 11q23.3 to the telomere. Haploinsufficiency of the deleted genes produces pre- and postnatal growth retardation, psychomotor retardation, characteristic facial dysmorphism, and — as a hallmark — a congenital platelet disorder (Paris-Trousseau thrombocytopenia, attributed to FLI1 haploinsufficiency). Malformations of the heart, kidney, gastrointestinal tract, genitalia, CNS, and skeleton are common, and congenital heart disease drives most early mortality.

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1
Inheritance
2
Pathophys.
13
Phenotypes
6
Pathograph
2
Genes
3
Medical Actions
2
Differentials
1
References
🏷

Classifications

Harrison's Part
GENETICS ENVIRONMENT DISEASE
IUIS Category
combined immunodeficiency with syndromic features
👪

Inheritance

1
De novo 11q terminal deletion, with an unbalanced-segregation minority HP:0000006
The 11q deletion acts in the heterozygous state. The 15% familial fraction is the counselling-relevant part: it reflects a balanced parental translocation segregating unbalanced, not direct transmission of the deletion, so parental karyotyping is indicated.
Autosomal dominant inheritance De novo rate: De novo in about 85% of reported cases; the remaining 15% arise from unbalanced segregation of a familial balanced translocation or other rearrangement.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"The deletion is de novo in 85% of reported cases, and in 15% of cases it results from an unbalanced segregation of a familial balanced translocation or from other chromosome rearrangements."
Gives both the de novo rate and the mechanism behind the familial minority.
⚙

Pathophysiology

2
Distal 11q Terminal Deletion
A partial deletion of the long arm of chromosome 11, from a proximal breakpoint within or telomeric to 11q23.3 extending usually to the telomere; deletion size ranges from ~7 to 20 Mb. Most are de novo.
Downstream
Haploinsufficiency of Distal 11q Genes The deletion removes one copy of the contiguous distal 11q genes.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"The deletion size ranges from approximately 7 to 20 Mb, with the proximal breakpoint within or telomeric to subband 11q23.3 and the deletion extending usually to the telomere."
Defines the location and size range of the causal 11q terminal deletion.
Haploinsufficiency of Distal 11q Genes
Reduced dosage of the contiguous distal 11q genes drives the multisystem phenotype. The congenital platelet disorder (Paris-Trousseau thrombocytopenia) is attributed to haploinsufficiency of FLI1 (11q24), a transcription factor required for megakaryopoiesis; other genes in the interval contribute to the cardiac, craniofacial, and neurodevelopmental features.
Downstream
Thrombocytopenia
Congenital Heart Defects
Intellectual Disability
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"Jacobsen syndrome is a MCA/MR contiguous gene syndrome caused by partial deletion of the long arm of chromosome 11."
Establishes Jacobsen syndrome as a contiguous-gene (haploinsufficiency) syndrome.
⬡

Pathograph

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

Phenotypes

13
Blood 1
Thrombocytopenia VERY_FREQUENT HP:0001873 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Thrombocytopenia (HP:0001873). HP:0001873 is a phenotype from the Human Phenotype Ontology.
Paris-Trousseau thrombocytopenia — abnormal platelet function and thrombocytopenia (sometimes pancytopenia), usually present at birth.
Show evidence (3 references)
PMID:19267933 SUPPORT Human Clinical
"Abnormal platelet function, thrombocytopenia or pancytopenia are usually present at birth."
Documents the hallmark congenital platelet disorder of Jacobsen syndrome.
PMID:19267933 SUPPORT Human Clinical
"is highly penetrant in JS, affecting at least 88.5% of cases"
Quantifies the near-complete penetrance of the Paris-Trousseau platelet abnormality, supporting the VERY_FREQUENT band.
PMID:19267933 SUPPORT Human Clinical
"In peripheral blood there are two different types of abnormal platelets: giant platelets and platelets with giant alpha granules."
Describes the characteristic Paris-Trousseau platelet morphology behind the persistent platelet dysfunction.
Cardiovascular 1
Congenital Heart Defects FREQUENT Abnormal heart morphology HP:0001627 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Congenital heart defect, annotated with Abnormal heart morphology (HP:0001627). HP:0001627 is a phenotype from the Human Phenotype Ontology.
A leading cause of early mortality: 56% of cases overall and 95% of deceased children. Ventricular septal defects and left-heart obstructive lesions (aortic/mitral valve abnormalities, coarctation, Shone complex, hypoplastic left heart syndrome) predominate; hypoplastic left heart syndrome occurs in about 5% of children.
Show evidence (4 references)
PMID:19267933 SUPPORT Human Clinical
"Patients commonly have malformations of the heart, kidney, gastrointestinal tract, genitalia, central nervous system and skeleton."
Cardiac malformations are among the common malformations.
PMID:19267933 SUPPORT Human Clinical
"Congenital heart malformations occur in 56% of cases."
Quantifies the cardiac-malformation rate, supporting the FREQUENT band.
PMID:19267933 SUPPORT Human Clinical
"Cardiac malformations were reported in 95% of deceased children"
Supports congenital heart disease as the leading driver of early mortality.
+ 1 more reference
Eye 3
Hypertelorism HP:0000316 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypertelorism (HP:0000316). HP:0000316 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears)"
Hypertelorism is part of the characteristic facial dysmorphism.
Ptosis HP:0000508 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ptosis (HP:0000508). HP:0000508 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears)"
Ptosis is part of the characteristic facial dysmorphism.
Coloboma HP:0000589 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Coloboma (HP:0000589). HP:0000589 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears)"
Coloboma is part of the characteristic facial dysmorphism.
Genitourinary 2
Renal Anomalies FREQUENT Abnormality of the kidney HP:0000077 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Kidney anomaly, annotated with Abnormality of the kidney (HP:0000077). HP:0000077 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"Patients commonly have malformations of the heart, kidney, gastrointestinal tract, genitalia, central nervous system and skeleton."
Renal malformations are among the common malformations.
Cryptorchidism FREQUENT HP:0000028 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cryptorchidism (HP:0000028). HP:0000028 is a phenotype from the Human Phenotype Ontology.
Male-limited; 36% of males in published reports and about 60% in the authors' directly assessed series.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"Cryptorchidism is observed in 36% of males"
Quantifies cryptorchidism among male patients, supporting the FREQUENT band.
Head and Neck 2
Downslanted Palpebral Fissures HP:0000494 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Downslanting palpebral fissures, annotated with Downslanted palpebral fissures (HP:0000494). HP:0000494 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears)"
Downslanting palpebral fissures are part of the characteristic facial dysmorphism.
Broad Nasal Bridge Wide nasal bridge HP:0000431 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Broad nasal bridge, annotated with Wide nasal bridge (HP:0000431). HP:0000431 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears)"
A broad nasal bridge is part of the characteristic facial dysmorphism.
Nervous System 3
Intellectual Disability VERY_FREQUENT HP:0001249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Psychomotor retardation, annotated with Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
Psychomotor retardation / intellectual deficit; part of the diagnostic triad. The degree of neurocognitive deficiency correlates with deletion size.
Show evidence (3 references)
PMID:19267933 SUPPORT Human Clinical
"The most common clinical features include pre- and postnatal physical growth retardation, psychomotor retardation, and characteristic facial dysmorphism"
Psychomotor retardation is among the most common features.
PMID:19267933 SUPPORT Human Clinical
"Mental development is normal or borderline in less than 3% of cases, mild to severe mental retardation is observed in 97% of cases."
Quantifies the near-universal cognitive involvement, supporting the VERY_FREQUENT band.
PMID:19267933 SUPPORT Human Clinical
"The degree of neurocognitive deficiency is strongly associated with the size of the deletion"
Supports the deletion-size genotype-phenotype correlation noted here.
Structural Brain Abnormalities FREQUENT Abnormal brain morphology HP:0012443 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Structural brain abnormality, annotated with Abnormal brain morphology (HP:0012443). HP:0012443 is a phenotype from the Human Phenotype Ontology.
Among patients studied by ultrasound, CT, MRI, or autopsy, 65% had a structural brain abnormality (enlarged ventricles, cerebral atrophy, agenesis of the corpus callosum, pachygyria); white-matter changes are interpreted as delayed myelination or partial astrocyte loss rather than demyelination.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"65% had some kind of structural abnormality of the brain: enlarged ventricles with or without spina bifida, cerebral atrophy, agenesis of corpus callosum, pachygiria"
Quantifies structural brain abnormalities among imaged or autopsied patients.
Attention Deficit Hyperactivity Disorder HP:0007018 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Attention deficit/hyperactivity disorder, annotated with Attention deficit hyperactivity disorder (HP:0007018). HP:0007018 is a phenotype from the Human Phenotype Ontology.
Behavioral problems are common, most frequently ADHD; more severe psychiatric disorders (schizophrenia, bipolar affective disorder) are reported rarely, and seizures are infrequent.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"Children manifest behavioral problems, most frequently attention deficit/hyperactivity disorder"
Identifies ADHD as the most frequent behavioral problem in Jacobsen syndrome.
Growth 1
Growth Retardation VERY_FREQUENT Growth delay HP:0001510 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Pre- and postnatal growth retardation, annotated with Growth delay (HP:0001510). HP:0001510 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:19267933 SUPPORT Human Clinical
"The most common clinical features include pre- and postnatal physical growth retardation, psychomotor retardation, and characteristic facial dysmorphism"
Pre- and postnatal growth retardation is among the most common features.
PMID:19267933 SUPPORT Human Clinical
"Height is below the 10th percentile in 75% of cases and in the normal range in 25%."
Quantifies short stature in the reviewed case series.
🧬

Genetic Associations

2
Distal 11q terminal deletion (Causal)
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"The deletion is de novo in 85% of reported cases, and in 15% of cases it results from an unbalanced segregation of a familial balanced translocation or from other chromosome rearrangements."
Gives the de novo vs familial-translocation origins of the deletion.
FLI1 (Causal for the Paris-Trousseau platelet phenotype)
Gene: FLI1 hgnc:3749 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is FLI1 (hgnc:3749). hgnc:3749 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"There is in vivo and in vitro evidence that FLI1 plays a fundamental role in megakaryocytes differentiation and that heterozygous loss of the FLI-1 gene is associated with dysmegakaryocytopoiesis and the Paris-Tousseau trombocytopenia in JS"
Directly attributes the Paris-Trousseau platelet phenotype to heterozygous FLI1 loss within the deletion (source spelling preserved).
💊

Medical Actions

3
Multidisciplinary Supportive Care
Action: supportive careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is supportive care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
No curative therapy exists. Management is multidisciplinary — cardiac care (heart surgery may be needed in the neonatal period), hematologic monitoring and bleeding precautions for the platelet disorder, feeding support, and ophthalmologic, auditory, endocrine, and immunologic follow-up.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"Management is multi-disciplinary and requires evaluation by general pediatrician, pediatric cardiologist, neurologist, ophthalmologist."
Establishes multidisciplinary supportive care as the management approach.
Prophylactic Platelet Transfusion
Action: platelet transfusionNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is platelet transfusion (NCIT:C15366). NCIT:C15366 is a clinical intervention from the NCI Thesaurus. Ontology label: Platelet Transfusion NCIT:C15366
Because of thrombocytopenia and persistent platelet dysfunction, bleeding risk is highest in infancy and around procedures; prophylactic platelet or whole-blood transfusion is used before, during, or after surgery.
Target Phenotypes: Thrombocytopenia HP:0001873 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Thrombocytopenia (HP:0001873). HP:0001873 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"Thrombocytopenia and other hematological problems must be taken into account preoperatively. Prophylactic transfusion with platelets can be lifesaving."
Supports perioperative prophylactic platelet transfusion for the bleeding diathesis.
Genetic Counseling and Prenatal Diagnosis
Category: Counseling / Informational Action: genetic counselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is genetic counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. Ontology label: Genetic Counseling NCIT:C15240
Recurrence risk after a de novo deletion is generally considered negligible, but recurrence has been documented, is 50% when a parent is affected, and is high with a parental balanced translocation or 11q mosaicism; prenatal cytogenetic diagnosis by amniocentesis or chorionic villus sampling is possible.
Show evidence (2 references)
PMID:19267933 SUPPORT Human Clinical
"There is a high recurrence risk when a parent has a balanced translocation, or deletion 11q in the mosaic form."
Identifies the family configurations with high recurrence risk.
PMID:19267933 SUPPORT Human Clinical
"Prenatal diagnosis of 11q deletion is possible by amniocentesis or chorionic villus sampling and cytogenetic analysis."
Documents the available prenatal diagnostic route.
🔬

Diagnosis

1
Karyotype/Chromosomal Microarray (distal 11q deletion)
Diagnosis is based on clinical findings (intellectual deficit, facial dysmorphism, and thrombocytopenia) and confirmed by cytogenetic analysis.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"Diagnosis is based on clinical findings (intellectual deficit, facial dysmorphic features and thrombocytopenia) and confirmed by cytogenetics analysis."
States the clinical diagnostic triad and cytogenetic confirmation.
📈

Progression

2
Neonatal period and infancy
Age: Birth to 2 years
The neonatal course is dominated by feeding difficulties, cardiac disease, and bleeding, often with prolonged hospitalization; about 20% of children die during the first two years, mostly from congenital heart disease complications and less commonly from bleeding.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"About 20% of children die during the first two years of life, most commonly related to complications from congenital heart disease, and less commonly from bleeding."
Quantifies early mortality and its leading causes.
Childhood and long-term course
Age: Childhood to adulthood
Half of patients are diagnosed by age one year; milder phenotypes are recognized later. Platelet counts can normalize over time but platelet dysfunction usually persists, and survivors need long-term multidisciplinary surgical and medical care.
Show evidence (2 references)
PMID:19267933 SUPPORT Human Clinical
"Half of the patients are diagnosed by age one year of life, usually those with the more obvious clinical features of the disorder"
Documents the typical timing of diagnosis across the severity spectrum.
PMID:19267933 SUPPORT Human Clinical
"Platelet count can eventually reach low normal values"
Documents that the platelet count can normalize over time; the same sentence (hyphen-broken in the cached full text) adds that functional abnormalities usually persist, which is carried in the notes.
📊

Prevalence

1
Live births
Birth Prevalence 1.0 per 100,000 1–9 per 100,000 (births)
Estimated at ~1 in 100,000 births, with a female-to-male ratio of about 2:1.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"The prevalence has been estimated at 1/100,000 births, with a female/male ratio 2:1."
Provides the ~1 in 100,000 prevalence and the female predominance.
⚖️

Clinical Burden

High
Early mortality is substantial (about 20% die in the first two years, mostly from congenital heart disease); survivors carry multisystem malformations, a lifelong platelet disorder, and near-universal intellectual disability requiring long-term multidisciplinary care, and life expectancy beyond infancy is unknown.
Show evidence (2 references)
PMID:19267933 SUPPORT Human Clinical
"About 20% of children die during the first two years of life, most commonly related to complications from congenital heart disease, and less commonly from bleeding."
Supports the high early-mortality component of the burden rating.
PMID:19267933 SUPPORT Human Clinical
"Many patients that survive the neonatal period will require long-term care including surgical and medical interventions. Life expectancy is unknown."
Supports the long-term multidisciplinary care requirement and prognostic uncertainty.
🔀

Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from Jacobsen Syndrome:

Turner syndrome MONDO:0019499
Overlapping Features Shares short stature, a short or webbed neck, downslanting palpebral fissures, ptosis, and left-sided cardiac lesions with Jacobsen syndrome.
Distinguishing Features
  • Cytogenetic analysis shows a 45,X or variant X-chromosome constitution rather than a distal 11q deletion.
  • Congenital thrombocytopenia is not a Turner syndrome feature.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"Differential diagnoses include Turner and Noonan syndromes, and acquired thrombocytopenia due to sepsis."
The review explicitly lists Turner syndrome in the Jacobsen syndrome differential.
Noonan syndrome MONDO:0018997
Overlapping Features Shares short stature, neck and palpebral anomalies, and congenital heart disease with Jacobsen syndrome, and additionally overlaps through thrombocytopenia with a bleeding tendency.
Distinguishing Features
  • Cytogenetic analysis is normal at 11q; molecular testing identifies a RAS-MAPK pathway gene variant.
Show evidence (1 reference)
PMID:19267933 SUPPORT Human Clinical
"Differential diagnoses include Turner and Noonan syndromes, and acquired thrombocytopenia due to sepsis."
The review explicitly lists Noonan syndrome in the Jacobsen syndrome differential.
{ }

Source YAML

click to show 
name: Jacobsen Syndrome
creation_date: "2026-08-22T00:00:00Z"
description: >-
  Jacobsen syndrome is a multiple-congenital-anomaly/intellectual-disability
  contiguous-gene syndrome caused by a partial deletion of the long arm of
  chromosome 11 (distal 11q), extending from a breakpoint at or telomeric to
  11q23.3 to the telomere. Haploinsufficiency of the deleted genes produces pre-
  and postnatal growth retardation, psychomotor retardation, characteristic facial
  dysmorphism, and — as a hallmark — a congenital platelet disorder
  (Paris-Trousseau thrombocytopenia, attributed to FLI1 haploinsufficiency).
  Malformations of the heart, kidney, gastrointestinal tract, genitalia, CNS, and
  skeleton are common, and congenital heart disease drives most early mortality.
category: Genetic
synonyms:
- 11q terminal deletion disorder
- distal 11q deletion syndrome
- partial monosomy 11q
- 11q deletion syndrome
parents:
- hereditary disease
- chromosomal disorder
classifications:
  harrisons_chapter:
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    notes: >-
      Contiguous-gene deletion syndrome caused by terminal deletion of
      chromosome 11q.
  iuis_category:
    classification_value: combined immunodeficiency with syndromic features
    notes: >-
      IUIS 2022 classification of inborn errors of immunity (Tangye et al.,
      PMID:35748970), Table 2 "Combined immunodeficiencies with associated or
      syndromic features", section 3 "Thymic Defects with Additional
      Congenital Anomalies", row "Chromosome 11q deletion syndrome (Jacobsen
      syndrome)" (11q23del, AD, OMIM 147791).
    evidence:
    - reference: PMID:35748970
      reference_title: "Human Inborn Errors of Immunity: 2022 Update on the Classification from the International Union of Immunological Societies Expert Committee."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Chromosome 11q deletion syndrome (Jacobsen syndrome) 11q23del AD 147791 Lymphopenia; low NK cells"
      explanation: >-
        Table 2 section 3 row identifying chromosome 11q deletion (Jacobsen)
        syndrome among combined immunodeficiencies with associated or
        syndromic features, with its lymphopenia/low-NK immunophenotype; the
        quote joins the row's wrapped lines in the cached PDF extraction.
disease_term:
  preferred_term: Jacobsen syndrome
  term:
    id: MONDO:0007838
    label: Jacobsen syndrome
inheritance:
- name: De novo 11q terminal deletion, with an unbalanced-segregation minority
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  de_novo_rate: >-
    De novo in about 85% of reported cases; the remaining 15% arise from
    unbalanced segregation of a familial balanced translocation or other
    rearrangement.
  description: >-
    The 11q deletion acts in the heterozygous state. The 15% familial fraction is
    the counselling-relevant part: it reflects a balanced parental translocation
    segregating unbalanced, not direct transmission of the deletion, so parental
    karyotyping is indicated.
  evidence:
  - reference: PMID:19267933
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The deletion is de novo in 85% of reported cases, and in 15% of cases it
      results from an unbalanced segregation of a familial balanced translocation
      or from other chromosome rearrangements.
    explanation: >-
      Gives both the de novo rate and the mechanism behind the familial minority.
prevalence:
- population: Live births
  measure_type: BIRTH_PREVALENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 1.0
  notes: >-
    Estimated at ~1 in 100,000 births, with a female-to-male ratio of about 2:1.
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The prevalence has been estimated at 1/100,000 births, with a female/male ratio 2:1."
    explanation: Provides the ~1 in 100,000 prevalence and the female predominance.
progression:
- phase: Neonatal period and infancy
  age_range: Birth to 2 years
  notes: >-
    The neonatal course is dominated by feeding difficulties, cardiac disease,
    and bleeding, often with prolonged hospitalization; about 20% of children
    die during the first two years, mostly from congenital heart disease
    complications and less commonly from bleeding.
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      About 20% of children die during the first two years of life, most
      commonly related to complications from congenital heart disease, and less
      commonly from bleeding.
    explanation: Quantifies early mortality and its leading causes.
- phase: Childhood and long-term course
  age_range: Childhood to adulthood
  notes: >-
    Half of patients are diagnosed by age one year; milder phenotypes are
    recognized later. Platelet counts can normalize over time but platelet
    dysfunction usually persists, and survivors need long-term
    multidisciplinary surgical and medical care.
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Half of the patients are diagnosed by age one year of life, usually those
      with the more obvious clinical features of the disorder
    explanation: Documents the typical timing of diagnosis across the severity spectrum.
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Platelet count can eventually reach low normal values"
    explanation: >-
      Documents that the platelet count can normalize over time; the same
      sentence (hyphen-broken in the cached full text) adds that functional
      abnormalities usually persist, which is carried in the notes.
clinical_burden:
  burden_level: HIGH
  rationale: >-
    Early mortality is substantial (about 20% die in the first two years,
    mostly from congenital heart disease); survivors carry multisystem
    malformations, a lifelong platelet disorder, and near-universal
    intellectual disability requiring long-term multidisciplinary care, and
    life expectancy beyond infancy is unknown.
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      About 20% of children die during the first two years of life, most
      commonly related to complications from congenital heart disease, and less
      commonly from bleeding.
    explanation: Supports the high early-mortality component of the burden rating.
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Many patients that survive the neonatal period will require long-term
      care including surgical and medical interventions. Life expectancy is
      unknown.
    explanation: Supports the long-term multidisciplinary care requirement and prognostic uncertainty.
pathophysiology:
- name: Distal 11q Terminal Deletion
  biological_scale: MOLECULAR
  description: >-
    A partial deletion of the long arm of chromosome 11, from a proximal breakpoint
    within or telomeric to 11q23.3 extending usually to the telomere; deletion size
    ranges from ~7 to 20 Mb. Most are de novo.
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The deletion size ranges from approximately 7 to 20 Mb, with the proximal breakpoint within or telomeric to subband 11q23.3 and the deletion extending usually to the telomere."
    explanation: Defines the location and size range of the causal 11q terminal deletion.
  downstream:
  - target: Haploinsufficiency of Distal 11q Genes
    causal_link_type: DIRECT
    description: The deletion removes one copy of the contiguous distal 11q genes.
- name: Haploinsufficiency of Distal 11q Genes
  biological_scale: MOLECULAR
  description: >-
    Reduced dosage of the contiguous distal 11q genes drives the multisystem
    phenotype. The congenital platelet disorder (Paris-Trousseau thrombocytopenia)
    is attributed to haploinsufficiency of FLI1 (11q24), a transcription factor
    required for megakaryopoiesis; other genes in the interval contribute to the
    cardiac, craniofacial, and neurodevelopmental features.
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Jacobsen syndrome is a MCA/MR contiguous gene syndrome caused by partial deletion of the long arm of chromosome 11."
    explanation: Establishes Jacobsen syndrome as a contiguous-gene (haploinsufficiency) syndrome.
  downstream:
  - target: Thrombocytopenia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - FLI1 haploinsufficiency impairing megakaryopoiesis
  - target: Congenital Heart Defects
    causal_link_type: DIRECT
  - target: Intellectual Disability
    causal_link_type: DIRECT
phenotypes:
- category: Hematologic
  name: Thrombocytopenia
  frequency: VERY_FREQUENT
  diagnostic: true
  notes: Paris-Trousseau thrombocytopenia — abnormal platelet function and thrombocytopenia (sometimes pancytopenia), usually present at birth.
  phenotype_term:
    preferred_term: Thrombocytopenia
    term:
      id: HP:0001873
      label: Thrombocytopenia
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Abnormal platelet function, thrombocytopenia or pancytopenia are usually present at birth."
    explanation: Documents the hallmark congenital platelet disorder of Jacobsen syndrome.
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "is highly penetrant in JS, affecting at least 88.5% of cases"
    explanation: >-
      Quantifies the near-complete penetrance of the Paris-Trousseau platelet
      abnormality, supporting the VERY_FREQUENT band.
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In peripheral blood there are two different types of abnormal platelets:
      giant platelets and platelets with giant alpha granules.
    explanation: >-
      Describes the characteristic Paris-Trousseau platelet morphology behind
      the persistent platelet dysfunction.
- category: Growth
  name: Growth Retardation
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Pre- and postnatal growth retardation
    term:
      id: HP:0001510
      label: Growth delay
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most common clinical features include pre- and postnatal physical growth retardation, psychomotor retardation, and characteristic facial dysmorphism"
    explanation: Pre- and postnatal growth retardation is among the most common features.
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Height is below the 10th percentile in 75% of cases and in the normal range in 25%."
    explanation: Quantifies short stature in the reviewed case series.
- category: Neurologic
  name: Intellectual Disability
  frequency: VERY_FREQUENT
  notes: >-
    Psychomotor retardation / intellectual deficit; part of the diagnostic
    triad. The degree of neurocognitive deficiency correlates with deletion
    size.
  phenotype_term:
    preferred_term: Psychomotor retardation
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most common clinical features include pre- and postnatal physical growth retardation, psychomotor retardation, and characteristic facial dysmorphism"
    explanation: Psychomotor retardation is among the most common features.
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mental development is normal or borderline in less than 3% of cases, mild
      to severe mental retardation is observed in 97% of cases.
    explanation: Quantifies the near-universal cognitive involvement, supporting the VERY_FREQUENT band.
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The degree of neurocognitive deficiency is strongly associated with the size of the deletion"
    explanation: Supports the deletion-size genotype-phenotype correlation noted here.
- category: Craniofacial
  name: Hypertelorism
  phenotype_term:
    preferred_term: Hypertelorism
    term:
      id: HP:0000316
      label: Hypertelorism
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears)"
    explanation: Hypertelorism is part of the characteristic facial dysmorphism.
- category: Ophthalmologic
  name: Ptosis
  phenotype_term:
    preferred_term: Ptosis
    term:
      id: HP:0000508
      label: Ptosis
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears)"
    explanation: Ptosis is part of the characteristic facial dysmorphism.
- category: Ophthalmologic
  name: Coloboma
  phenotype_term:
    preferred_term: Coloboma
    term:
      id: HP:0000589
      label: Coloboma
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears)"
    explanation: Coloboma is part of the characteristic facial dysmorphism.
- category: Craniofacial
  name: Downslanted Palpebral Fissures
  phenotype_term:
    preferred_term: Downslanting palpebral fissures
    term:
      id: HP:0000494
      label: Downslanted palpebral fissures
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears)"
    explanation: Downslanting palpebral fissures are part of the characteristic facial dysmorphism.
- category: Craniofacial
  name: Broad Nasal Bridge
  phenotype_term:
    preferred_term: Broad nasal bridge
    term:
      id: HP:0000431
      label: Wide nasal bridge
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears)"
    explanation: A broad nasal bridge is part of the characteristic facial dysmorphism.
- category: Cardiac
  name: Congenital Heart Defects
  frequency: FREQUENT
  notes: >-
    A leading cause of early mortality: 56% of cases overall and 95% of
    deceased children. Ventricular septal defects and left-heart obstructive
    lesions (aortic/mitral valve abnormalities, coarctation, Shone complex,
    hypoplastic left heart syndrome) predominate; hypoplastic left heart
    syndrome occurs in about 5% of children.
  phenotype_term:
    preferred_term: Congenital heart defect
    term:
      id: HP:0001627
      label: Abnormal heart morphology
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients commonly have malformations of the heart, kidney, gastrointestinal tract, genitalia, central nervous system and skeleton."
    explanation: Cardiac malformations are among the common malformations.
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Congenital heart malformations occur in 56% of cases."
    explanation: Quantifies the cardiac-malformation rate, supporting the FREQUENT band.
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cardiac malformations were reported in 95% of deceased children"
    explanation: Supports congenital heart disease as the leading driver of early mortality.
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hypoplastic left heart syndrome, a rare and severe condition that occurs
      in about 1/5000 infants, is observed in 5% of JS children.
    explanation: Quantifies the marked enrichment of hypoplastic left heart syndrome in Jacobsen syndrome.
- category: Renal
  name: Renal Anomalies
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Kidney anomaly
    term:
      id: HP:0000077
      label: Abnormality of the kidney
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients commonly have malformations of the heart, kidney, gastrointestinal tract, genitalia, central nervous system and skeleton."
    explanation: Renal malformations are among the common malformations.
- category: Neurologic
  name: Structural Brain Abnormalities
  frequency: FREQUENT
  notes: >-
    Among patients studied by ultrasound, CT, MRI, or autopsy, 65% had a
    structural brain abnormality (enlarged ventricles, cerebral atrophy,
    agenesis of the corpus callosum, pachygyria); white-matter changes are
    interpreted as delayed myelination or partial astrocyte loss rather than
    demyelination.
  phenotype_term:
    preferred_term: Structural brain abnormality
    term:
      id: HP:0012443
      label: Abnormal brain morphology
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      65% had some kind of structural abnormality of the brain: enlarged
      ventricles with or without spina bifida, cerebral atrophy, agenesis of
      corpus callosum, pachygiria
    explanation: Quantifies structural brain abnormalities among imaged or autopsied patients.
- category: Behavioral
  name: Attention Deficit Hyperactivity Disorder
  notes: >-
    Behavioral problems are common, most frequently ADHD; more severe
    psychiatric disorders (schizophrenia, bipolar affective disorder) are
    reported rarely, and seizures are infrequent.
  phenotype_term:
    preferred_term: Attention deficit/hyperactivity disorder
    term:
      id: HP:0007018
      label: Attention deficit hyperactivity disorder
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Children manifest behavioral problems, most frequently attention deficit/hyperactivity disorder"
    explanation: Identifies ADHD as the most frequent behavioral problem in Jacobsen syndrome.
- category: Genitourinary
  name: Cryptorchidism
  frequency: FREQUENT
  notes: >-
    Male-limited; 36% of males in published reports and about 60% in the
    authors' directly assessed series.
  phenotype_term:
    preferred_term: Cryptorchidism
    term:
      id: HP:0000028
      label: Cryptorchidism
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cryptorchidism is observed in 36% of males"
    explanation: Quantifies cryptorchidism among male patients, supporting the FREQUENT band.
genetic:
- name: Distal 11q terminal deletion
  association: Causal
  notes: >-
    Partial deletion of distal 11q (copy-number loss), ~7-20 Mb, from a breakpoint
    at or telomeric to 11q23.3 to the telomere. De novo in ~85% of cases; ~15%
    arise from unbalanced segregation of a familial balanced translocation or other
    rearrangement, and a minority from breakage at the FRA11B fragile site. No
    coordinate slot exists in the schema; the deletion is recorded here in prose.
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The deletion is de novo in 85% of reported cases, and in 15% of cases it results from an unbalanced segregation of a familial balanced translocation or from other chromosome rearrangements."
    explanation: Gives the de novo vs familial-translocation origins of the deletion.
- name: FLI1
  gene_term:
    preferred_term: FLI1
    term:
      id: hgnc:3749
      label: FLI1
  association: Causal for the Paris-Trousseau platelet phenotype
  relationship_type: CAUSATIVE
  notes: >-
    FLI1 (11q24) encodes an ETS transcription factor essential for
    megakaryopoiesis; its haploinsufficiency within the deletion is the
    recognized cause of the Paris-Trousseau thrombocytopenia and abnormal
    platelet function — a component phenotype of the contiguous-gene deletion,
    not the whole syndrome. In vitro over-expression of FLI1 in
    haploinsufficient patient CD34+ cells restores normal megakaryopoiesis,
    though the source notes other distal 11q genes may also contribute.
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There is in vivo and in vitro evidence that FLI1 plays a fundamental role
      in megakaryocytes differentiation and that heterozygous loss of the FLI-1
      gene is associated with dysmegakaryocytopoiesis and the Paris-Tousseau
      trombocytopenia in JS
    explanation: >-
      Directly attributes the Paris-Trousseau platelet phenotype to
      heterozygous FLI1 loss within the deletion (source spelling preserved).
diagnosis:
- name: Karyotype/Chromosomal Microarray
  presence: distal 11q deletion
  notes: >-
    Diagnosis is based on clinical findings (intellectual deficit, facial
    dysmorphism, and thrombocytopenia) and confirmed by cytogenetic analysis.
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Diagnosis is based on clinical findings (intellectual deficit, facial dysmorphic features and thrombocytopenia) and confirmed by cytogenetics analysis."
    explanation: States the clinical diagnostic triad and cytogenetic confirmation.
differential_diagnoses:
- name: Turner syndrome
  description: >-
    Shares short stature, a short or webbed neck, downslanting palpebral
    fissures, ptosis, and left-sided cardiac lesions with Jacobsen syndrome.
  distinguishing_features:
  - Cytogenetic analysis shows a 45,X or variant X-chromosome constitution rather than a distal 11q deletion.
  - Congenital thrombocytopenia is not a Turner syndrome feature.
  disease_term:
    preferred_term: Turner syndrome
    term:
      id: MONDO:0019499
      label: Turner syndrome
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Differential diagnoses include Turner and Noonan syndromes, and acquired thrombocytopenia due to sepsis."
    explanation: The review explicitly lists Turner syndrome in the Jacobsen syndrome differential.
- name: Noonan syndrome
  description: >-
    Shares short stature, neck and palpebral anomalies, and congenital heart
    disease with Jacobsen syndrome, and additionally overlaps through
    thrombocytopenia with a bleeding tendency.
  distinguishing_features:
  - Cytogenetic analysis is normal at 11q; molecular testing identifies a RAS-MAPK pathway gene variant.
  disease_term:
    preferred_term: Noonan syndrome
    term:
      id: MONDO:0018997
      label: Noonan syndrome
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Differential diagnoses include Turner and Noonan syndromes, and acquired thrombocytopenia due to sepsis."
    explanation: The review explicitly lists Noonan syndrome in the Jacobsen syndrome differential.
treatments:
- name: Multidisciplinary Supportive Care
  description: >-
    No curative therapy exists. Management is multidisciplinary — cardiac care
    (heart surgery may be needed in the neonatal period), hematologic monitoring and
    bleeding precautions for the platelet disorder, feeding support, and
    ophthalmologic, auditory, endocrine, and immunologic follow-up.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Management is multi-disciplinary and requires evaluation by general pediatrician, pediatric cardiologist, neurologist, ophthalmologist."
    explanation: Establishes multidisciplinary supportive care as the management approach.
- name: Prophylactic Platelet Transfusion
  description: >-
    Because of thrombocytopenia and persistent platelet dysfunction, bleeding
    risk is highest in infancy and around procedures; prophylactic platelet or
    whole-blood transfusion is used before, during, or after surgery.
  treatment_term:
    preferred_term: platelet transfusion
    term:
      id: NCIT:C15366
      label: Platelet Transfusion
  target_phenotypes:
  - preferred_term: Thrombocytopenia
    term:
      id: HP:0001873
      label: Thrombocytopenia
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Thrombocytopenia and other hematological problems must be taken into
      account preoperatively. Prophylactic transfusion with platelets can be
      lifesaving.
    explanation: Supports perioperative prophylactic platelet transfusion for the bleeding diathesis.
- name: Genetic Counseling and Prenatal Diagnosis
  action_category: COUNSELING_INFORMATIONAL
  description: >-
    Recurrence risk after a de novo deletion is generally considered
    negligible, but recurrence has been documented, is 50% when a parent is
    affected, and is high with a parental balanced translocation or 11q
    mosaicism; prenatal cytogenetic diagnosis by amniocentesis or chorionic
    villus sampling is possible.
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There is a high recurrence risk when a parent has a balanced
      translocation, or deletion 11q in the mosaic form.
    explanation: Identifies the family configurations with high recurrence risk.
  - reference: PMID:19267933
    reference_title: "Jacobsen syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Prenatal diagnosis of 11q deletion is possible by amniocentesis or
      chorionic villus sampling and cytogenetic analysis.
    explanation: Documents the available prenatal diagnostic route.
notes: >-
  Curated primarily from the Mattina, Perrotta, and Grossfeld Orphanet Journal
  of Rare Diseases review (PMID:19267933, full text cached). That review
  reports no known increased risk of malignancy in Jacobsen syndrome while
  noting that longer survival could yet reveal one; growth hormone replacement
  is described there as controversial for the same reason and is deliberately
  not curated as a treatment. Endocrine (growth hormone/IGF-1 and TSH
  deficiency) and immunologic (occasionally low IgM/IgA) problems are described
  only qualitatively in the source and are covered by the supportive-care
  follow-up entry rather than as separate evidence-banded phenotypes.
references:
- reference: PMID:19267933
  title: "Jacobsen syndrome."
📚

References & Deep Research

References

1
PMID:19267933
Jacobsen syndrome.
No top-level findings curated for this source.