Arthrogryposis Multiplex Congenita

Genetic MONDO:0015168 Pathograph 7 Congenital Disorder

Arthrogryposis Multiplex Congenita (AMC) is an umbrella clinical diagnosis defined by congenital joint contractures involving two or more different body areas. AMC is etiologically heterogeneous, encompassing more than 400 distinct genetic disorders as well as the most common sporadic form, Amyoplasia. Across all forms, the shared mechanistic final common pathway is decreased fetal movement (fetal akinesia) in utero, which produces secondary congenital contractures, craniofacial features, and limb-position deformities. Major clinical groups include Amyoplasia (classical AMC, sporadic, with symmetric severe limb contractures and characteristically normal cognition), the distal arthrogryposes (autosomal dominant disorders that preferentially affect the hands and feet, including DA1, DA2A/Freeman-Sheldon, and DA2B/Sheldon-Hall), the multiple pterygium syndromes, and the lethal congenital contracture syndromes (LCCS). Diagnosis combines clinical pattern recognition with molecular testing (exome or genome sequencing), and management is lifelong, multidisciplinary, and centered on early intensive physiotherapy, bracing, and selective orthopedic surgery.

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3
Inheritance
3
Pathophys.
5
Phenotypes
7
Pathograph
3
Genes
5
Treatments
4
Subtypes
9
References
1
Deep Research
👪

Inheritance

3
Sporadic (Amyoplasia) HP:0003745
Amyoplasia, the most common single form of AMC, occurs sporadically with no consistent Mendelian inheritance and an excess of discordant monozygotic twins.
Sporadic
Show evidence (1 reference)
PMID:24459070 SUPPORT Human Clinical
"Amyoplasia appears to be completely sporadic."
Hall's 560-patient series directly characterizes Amyoplasia as a sporadic condition.
Autosomal dominant (distal arthrogryposes) HP:0000006
The distal arthrogryposis syndromes (DA1, DA2A/Freeman-Sheldon, DA2B/Sheldon-Hall) are typically autosomal dominant disorders caused by heterozygous variants in genes encoding sarcomeric contractile proteins.
Autosomal dominant inheritance
Show evidence (1 reference)
PMID:32799913 SUPPORT Model Organism
"Distal arthrogryposis (DA) is a group of autosomal dominant skeletal muscle diseases characterized by congenital contractures of distal limb joints."
Guo et al. (a Drosophila modeling paper) frame the distal arthrogryposes as a group of autosomal dominant skeletal muscle diseases in their introduction; this background statement supports the autosomal dominant inheritance characterization for the DA syndromes.
Autosomal recessive (subset) HP:0000007
Selected AMC forms — including the autosomal recessive multiple pterygium syndromes and rare biallelic distal arthrogryposis cases — follow autosomal recessive inheritance.
Autosomal recessive inheritance
Show evidence (1 reference)
PMID:38856159 SUPPORT Human Clinical
"This is the first report of biallelic variants in MYH3 being implicated in a distal arthrogryposis phenotype without the additional features of CPSFS."
Morali et al. establish biallelic MYH3 as a recessive cause of distal arthrogryposis, supporting recessive inheritance in a subset of AMC.
◆

Subtypes

4
Amyoplasia (classical AMC) MONDO:0044629
Most common single form of AMC. Sporadic, with symmetric severe limb contractures, fatty-fibrous muscle replacement, characteristic limb positioning (extended elbows, equinovarus feet), and typically preserved cognition. Approximately 56% of cases show four-limb symmetric involvement.
Distal arthrogryposis (DA1, DA2A/Freeman-Sheldon, DA2B/Sheldon-Hall) MONDO:0019942
A group of autosomal dominant disorders that primarily affect the hands and feet. DA1 is the mildest, DA2A (Freeman-Sheldon) the most severe with distinctive facial contractures, and DA2B (Sheldon-Hall) is moderately severe. Caused predominantly by variants in sarcomeric contractile-protein genes (MYH3, TPM2, TNNI2).
Multiple Pterygium Syndromes MONDO:0017415
Disorders in which congenital contractures coexist with pterygia (webbing across flexural joints), often craniofacial features, and scoliosis. Includes the autosomal recessive nonlethal Escobar variant (most often CHRNG-related) and the lethal multiple pterygium syndrome.
Lethal congenital contracture syndromes MONDO:0009670
A group of prenatal-lethal or perinatal-lethal disorders within the fetal akinesia deformation sequence spectrum, characterized by severe fetal hypokinesia, multiple congenital contractures, pulmonary hypoplasia, and polyhydramnios.
⚙

Pathophysiology

3
Decreased fetal movement
All forms of AMC share decreased in utero fetal movement (fetal akinesia) as a unifying mechanism. Reduced fetal movement prevents normal joint development and produces fixed contractures, craniofacial features, and associated deformation findings.
skeletal muscle fiber link
skeletal muscle contraction link ↓ DECREASED
Downstream
Congenital joint contracture formation
Show evidence (1 reference)
PMID:27587986 SUPPORT Human Clinical
"All types of arthrogryposis have decreased in utero fetal movement."
Hall and Kiefer's GO synthesis directly states that decreased fetal movement is shared across all arthrogryposis types.
Sarcomeric contractile-protein dysfunction
In the distal arthrogryposis syndromes, heterozygous variants in genes encoding sarcomeric contractile proteins — embryonic myosin heavy chain (MYH3), beta-tropomyosin (TPM2), and fast skeletal troponin I (TNNI2) — disrupt actomyosin interactions in developing skeletal muscle. Functional studies indicate that these variants produce prolonged actomyosin binding and altered force generation, reducing effective fetal movement and producing congenital limb contractures.
skeletal muscle fiber link
muscle contraction link ⚠ ABNORMAL
Downstream
Decreased fetal movement
Show evidence (2 references)
PMID:32799913 SUPPORT Model Organism
"The defects observed in our DA1 and DA2B Drosophila models provide insight into DA phenotypes in humans, suggesting that contractures arise from prolonged actomyosin interactions."
The Drosophila DA1/DA2B myosin models directly support a prolonged actomyosin interaction mechanism in sarcomeric forms of AMC.
PMID:32799913 SUPPORT Human Clinical
"The most common cause of DA is a mutation of the embryonic myosin heavy chain gene, MYH3."
MYH3 is identified as the most common DA gene, supporting the centrality of sarcomeric myosin in distal AMC.
Congenital joint contracture formation
Persistent fetal hypokinesia prevents normal stretching of muscle and periarticular connective tissue, leading to fatty-fibrous replacement of muscle and fixed congenital contractures of two or more joints. The distribution and severity of contractures distinguishes AMC subtypes.
skeletal muscle fiber link
skeletal muscle tissue development link ⚠ ABNORMAL
Show evidence (1 reference)
PMID:24459070 SUPPORT Human Clinical
"Affected limbs had characteristic positions with fatty-fibrous replacement of muscle."
The 560-patient Amyoplasia series directly documents fatty-fibrous muscle replacement underlying the contracture phenotype.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Arthrogryposis Multiplex Congenita 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

5
Limbs 1
Talipes equinovarus Talipes equinovarus (HP:0001762)
Show evidence (1 reference)
PMID:24459070 SUPPORT Human Clinical
"equinovarus positioning of feet was almost always present"
The Amyoplasia series directly reports near-universal equinovarus foot positioning at birth.
Other 4
Congenital contracture Congenital contracture (HP:0002803)
Show evidence (1 reference)
PMID:38856159 SUPPORT Human Clinical
"Arthrogryposis is a clinical feature defined by congenital joint contractures in two or more different body areas which occurs in between 1/3000 and 1/5000 live births."
Morali et al. provide the standard clinical definition of arthrogryposis as congenital joint contractures in two or more body areas.
Limb joint contracture Limb joint contracture (HP:0003121)
Show evidence (1 reference)
PMID:24459070 SUPPORT Human Clinical
"Upper limb involvement was usually characterized by extended elbows. Lower limbs were held in various positions at birth; however, equinovarus positioning of feet was almost always present."
The Amyoplasia series documents characteristic limb-joint contracture positioning involving elbows and feet.
Decreased fetal movement Decreased fetal movement (HP:0001558)
Show evidence (1 reference)
PMID:27587986 SUPPORT Human Clinical
"All types of arthrogryposis have decreased in utero fetal movement."
Hall and Kiefer document decreased fetal movement as a shared feature across arthrogryposis types.
Arthrogryposis multiplex congenita Arthrogryposis multiplex congenita (HP:0002804)
Show evidence (1 reference)
PMID:38856159 SUPPORT Human Clinical
"Arthrogryposis is a clinical feature defined by congenital joint contractures in two or more different body areas"
Morali et al. supply the standard "two or more body areas" definition that aligns the AMC phenotype with HP:0002804.
🧬

Genetic Associations

3
Heterozygous MYH3 variants (Causative)
Show evidence (2 references)
PMID:25256237 SUPPORT Human Clinical
"MYH3 mutations were found in 43/46 (93%) kindreds, with three mutations (p.T178I, p.R672C, and p.R672H) explaining 39/43 (91%) of cases."
The Beck FSS series quantifies the dominance of three recurrent MYH3 missense variants in DA2A.
PMID:38856159 SUPPORT Human Clinical
"Heterozygous variants in MYH3 have been identified to cause the dominantly-inherited distal arthrogryposis conditions, Freeman-Sheldon syndrome, Sheldon-Hall syndrome, and multiple pterygium syndrome."
Morali et al. enumerate the dominant MYH3-associated AMC syndromes.
Heterozygous TPM2 variants (Causative)
Show evidence (1 reference)
PMID:30285720 SUPPORT Human Clinical
"A heterozygous missense mutation c.308A > G (p.Q103R) in TPM2 in Family 1"
Li et al. directly demonstrate a heterozygous TPM2 missense variant segregating with DA2B in a multigenerational family.
Heterozygous TNNI2 variants (Associated)
Show evidence (1 reference)
PMID:30285720 PARTIAL Human Clinical
"two-point linkage analysis was performed with microsatellite markers closed to TPM2, TNNI2/TNNT3 and TNNC2"
Li et al. include TPM2, TNNI2/TNNT3, and TNNC2 as established DA linkage candidate loci in their analysis, supporting TNNI2's inclusion in the DA thin-filament gene set; the paper does not itself demonstrate a causal TNNI2 variant (TPM2 was the causal gene in Family 1).
💊

Treatments

5
Early intensive physiotherapy
Action: physical therapy MAXO:0000011
Very early and aggressive physiotherapy in the neonatal and infant period is the foundation of AMC management and is associated with improved joint mobility and functional outcomes.
Target Phenotypes: Limb joint contracture ↗
Show evidence (1 reference)
PMID:31479584 SUPPORT Human Clinical
"The importance of very early and aggressive management of these deformities in the form of intensive physiotherapy (with its various modalities) and bracing is emphasized."
The Shriners multiauthored review supports early aggressive physiotherapy and bracing as central AMC management.
Bracing and orthotic management
Action: rehabilitation Ontology label: Rehabilitation NCIT:C15315
Orthotic bracing supports joint position and maintains range of motion achieved through physiotherapy and serial casting. Bracing is used across upper and lower extremity contractures and is integrated with surgical care.
Target Phenotypes: Limb joint contracture ↗
Show evidence (1 reference)
PMID:31479584 SUPPORT Human Clinical
"Separate sections address various hip, knee, foot, and ankle issues as well as orthotic treatment and functional outcomes."
The Shriners review devotes dedicated discussion to orthotic management across lower-limb joints in AMC.
Orthopedic surgery for joint contractures
Action: surgical procedure MAXO:0000004
Selective orthopedic surgical procedures — including soft-tissue release, osteotomies, gradual correction with external fixation, and selective quadriceps procedures for knee contractures — address residual contractures not corrected by physiotherapy and bracing.
Target Phenotypes: Limb joint contracture ↗
Show evidence (1 reference)
PMID:22875688 SUPPORT Human Clinical
"Surgical procedures vary with severity of contracture and patient age and include soft-tissue release, femoral shortening-extension osteotomy, gradual correction with Ilizarov, and femoral anterior epiphysiodesis."
Lampasi et al. enumerate the standard orthopedic surgical procedures used to correct AMC knee contractures.
Multidisciplinary care
Action: supportive care MAXO:0000950
Care for individuals with AMC requires a coordinated multidisciplinary approach involving genetics, orthopedics, rehabilitation, and family stakeholders across the lifespan.
Show evidence (1 reference)
PMID:31479584 SUPPORT Human Clinical
"The central role of a multidisciplinary approach involving all stakeholders, especially the families, is also discussed."
The Shriners review emphasizes a multidisciplinary care model for AMC.
Genetic counseling
Action: genetic counseling MAXO:0000079
Genetic counseling addresses the wide heterogeneity of AMC, the sporadic nature of Amyoplasia, autosomal dominant or recessive recurrence risk in the Mendelian forms, and prenatal or preimplantation testing options.
{ }

Source YAML

click to show 
name: Arthrogryposis Multiplex Congenita
creation_date: "2026-05-13T12:00:00Z"
updated_date: "2026-05-14T12:00:00Z"
category: Genetic
description: >-
  Arthrogryposis Multiplex Congenita (AMC) is an umbrella clinical diagnosis
  defined by congenital joint contractures involving two or more different body
  areas. AMC is etiologically heterogeneous, encompassing more than 400 distinct
  genetic disorders as well as the most common sporadic form, Amyoplasia. Across
  all forms, the shared mechanistic final common pathway is decreased fetal
  movement (fetal akinesia) in utero, which produces secondary congenital
  contractures, craniofacial features, and limb-position deformities. Major
  clinical groups include Amyoplasia (classical AMC, sporadic, with symmetric
  severe limb contractures and characteristically normal cognition), the distal
  arthrogryposes (autosomal dominant disorders that preferentially affect the
  hands and feet, including DA1, DA2A/Freeman-Sheldon, and DA2B/Sheldon-Hall),
  the multiple pterygium syndromes, and the lethal congenital contracture
  syndromes (LCCS). Diagnosis combines clinical pattern recognition with
  molecular testing (exome or genome sequencing), and management is lifelong,
  multidisciplinary, and centered on early intensive physiotherapy, bracing,
  and selective orthopedic surgery.
references:
- reference: PMID:24459070
  title: Amyoplasia revisited.
  findings:
  - statement: Amyoplasia is the most common form of AMC, is sporadic, and shows characteristic symmetric limb positions with fatty-fibrous muscle replacement.
    supporting_text: >-
      Hall's large 560-patient series provides the canonical clinical description
      of Amyoplasia and supports the sporadic recurrence pattern.
- reference: PMID:24459095
  title: Amyoplasia involving only the upper limbs or only involving the lower limbs with review of the relevant differential diagnoses.
- reference: PMID:27587986
  title: "Arthrogryposis as a Syndrome: Gene Ontology Analysis."
  findings:
  - statement: All forms of arthrogryposis share decreased in utero fetal movement as the unifying mechanism.
    supporting_text: >-
      Hall and Kiefer's GO-based reanalysis explicitly frames decreased fetal
      movement as the shared mechanistic pathway across genetic AMC subtypes.
- reference: PMID:25256237
  title: Genotype-phenotype relationships in Freeman-Sheldon syndrome.
  findings:
  - statement: Freeman-Sheldon syndrome (DA2A) is caused by MYH3 mutations and is the most severe of the distal arthrogryposis syndromes.
    supporting_text: >-
      Beck et al. characterized MYH3 genotype-phenotype relationships in 46 DA2A
      families, supporting DA2A classification and severity ranking among the DAs.
- reference: PMID:38856159
  title: Bi-allelic variants in MYH3 cause recessively-inherited arthrogryposis.
  findings:
  - statement: MYH3 underlies multiple dominantly inherited distal arthrogryposis syndromes including Freeman-Sheldon, Sheldon-Hall, and a multiple pterygium phenotype.
    supporting_text: >-
      Morali et al. summarize the dominant MYH3-associated AMC syndromes and
      extend the gene to recessive distal arthrogryposis.
- reference: PMID:30285720
  title: Novel mutations in TPM2 and PIEZO2 are responsible for distal arthrogryposis (DA) 2B and mild DA in two Chinese families.
  findings:
  - statement: TPM2 mutations cause distal arthrogryposis type 2B (Sheldon-Hall syndrome).
    supporting_text: >-
      Li et al. mapped a DA2B family to TPM2 and identified a pathogenic missense
      variant, supporting the TPM2-DA2B association.
- reference: PMID:32799913
  title: Drosophila myosin mutants model the disparate severity of type 1 and type 2B distal arthrogryposis and indicate an enhanced actin affinity mechanism.
  findings:
  - statement: Distal arthrogryposis contractures arise from prolonged actomyosin interactions in sarcomeric muscle.
    supporting_text: >-
      Guo et al. used Drosophila DA1 and DA2B myosin models to show that prolonged
      myosin-actin binding underlies the disparate severity of these DA forms.
- reference: PMID:31479584
  title: Treatment and outcomes of arthrogryposis in the lower extremity.
  findings:
  - statement: Early, intensive physiotherapy and bracing combined with selective surgery is the core management of AMC.
    supporting_text: >-
      The multiauthored Shriners review supports the centrality of early
      physiotherapy and orthopedic intervention in AMC management.
- reference: PMID:22875688
  title: Management of knee deformities in children with arthrogryposis.
synonyms:
- AMC
- Arthrogryposis
- Multiple congenital contractures
disease_term:
  preferred_term: arthrogryposis multiplex congenita
  term:
    id: MONDO:0015168
    label: arthrogryposis multiplex congenita
parents:
- Congenital Disorder
inheritance:
- name: Sporadic (Amyoplasia)
  inheritance_term:
    preferred_term: Sporadic
    term:
      id: HP:0003745
      label: Sporadic
  description: >-
    Amyoplasia, the most common single form of AMC, occurs sporadically with no
    consistent Mendelian inheritance and an excess of discordant monozygotic
    twins.
  evidence:
  - reference: PMID:24459070
    reference_title: Amyoplasia revisited.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Amyoplasia appears to be completely sporadic."
    explanation: >-
      Hall's 560-patient series directly characterizes Amyoplasia as a sporadic
      condition.
- name: Autosomal dominant (distal arthrogryposes)
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    The distal arthrogryposis syndromes (DA1, DA2A/Freeman-Sheldon,
    DA2B/Sheldon-Hall) are typically autosomal dominant disorders caused by
    heterozygous variants in genes encoding sarcomeric contractile proteins.
  evidence:
  - reference: PMID:32799913
    reference_title: Drosophila myosin mutants model the disparate severity of type 1 and type 2B distal arthrogryposis and indicate an enhanced actin affinity mechanism.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Distal arthrogryposis (DA) is a group of autosomal dominant skeletal muscle diseases characterized by congenital contractures of distal limb joints."
    explanation: >-
      Guo et al. (a Drosophila modeling paper) frame the distal arthrogryposes
      as a group of autosomal dominant skeletal muscle diseases in their
      introduction; this background statement supports the autosomal dominant
      inheritance characterization for the DA syndromes.
- name: Autosomal recessive (subset)
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    Selected AMC forms — including the autosomal recessive multiple pterygium
    syndromes and rare biallelic distal arthrogryposis cases — follow autosomal
    recessive inheritance.
  evidence:
  - reference: PMID:38856159
    reference_title: Bi-allelic variants in MYH3 cause recessively-inherited arthrogryposis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This is the first report of biallelic variants in MYH3 being implicated in a distal arthrogryposis phenotype without the additional features of CPSFS."
    explanation: >-
      Morali et al. establish biallelic MYH3 as a recessive cause of distal
      arthrogryposis, supporting recessive inheritance in a subset of AMC.
has_subtypes:
- name: Amyoplasia
  display_name: Amyoplasia (classical AMC)
  description: >-
    Most common single form of AMC. Sporadic, with symmetric severe limb
    contractures, fatty-fibrous muscle replacement, characteristic limb
    positioning (extended elbows, equinovarus feet), and typically preserved
    cognition. Approximately 56% of cases show four-limb symmetric involvement.
  subtype_term:
    preferred_term: congenital amyoplasia
    term:
      id: MONDO:0044629
      label: congenital amyoplasia
- name: Distal Arthrogryposis
  display_name: Distal arthrogryposis (DA1, DA2A/Freeman-Sheldon, DA2B/Sheldon-Hall)
  description: >-
    A group of autosomal dominant disorders that primarily affect the hands and
    feet. DA1 is the mildest, DA2A (Freeman-Sheldon) the most severe with
    distinctive facial contractures, and DA2B (Sheldon-Hall) is moderately
    severe. Caused predominantly by variants in sarcomeric contractile-protein
    genes (MYH3, TPM2, TNNI2).
  subtype_term:
    preferred_term: distal arthrogryposis
    term:
      id: MONDO:0019942
      label: distal arthrogryposis
- name: Multiple Pterygium Syndromes
  description: >-
    Disorders in which congenital contractures coexist with pterygia (webbing
    across flexural joints), often craniofacial features, and scoliosis.
    Includes the autosomal recessive nonlethal Escobar variant (most often
    CHRNG-related) and the lethal multiple pterygium syndrome.
  subtype_term:
    preferred_term: multiple pterygium syndrome
    term:
      id: MONDO:0017415
      label: multiple pterygium syndrome
- name: LCCS
  display_name: Lethal congenital contracture syndromes
  description: >-
    A group of prenatal-lethal or perinatal-lethal disorders within the fetal
    akinesia deformation sequence spectrum, characterized by severe fetal
    hypokinesia, multiple congenital contractures, pulmonary hypoplasia, and
    polyhydramnios.
  subtype_term:
    preferred_term: lethal congenital contracture syndrome 1
    term:
      id: MONDO:0009670
      label: lethal congenital contracture syndrome 1
pathophysiology:
- name: Decreased fetal movement
  description: >-
    All forms of AMC share decreased in utero fetal movement (fetal akinesia)
    as a unifying mechanism. Reduced fetal movement prevents normal joint
    development and produces fixed contractures, craniofacial features, and
    associated deformation findings.
  cell_types:
  - preferred_term: skeletal muscle fiber
    term:
      id: CL:0008002
      label: skeletal muscle fiber
  biological_processes:
  - preferred_term: skeletal muscle contraction
    modifier: DECREASED
    term:
      id: GO:0003009
      label: skeletal muscle contraction
  evidence:
  - reference: PMID:27587986
    reference_title: "Arthrogryposis as a Syndrome: Gene Ontology Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All types of arthrogryposis have decreased in utero fetal movement."
    explanation: >-
      Hall and Kiefer's GO synthesis directly states that decreased fetal
      movement is shared across all arthrogryposis types.
  downstream:
  - target: Congenital joint contracture formation
- name: Sarcomeric contractile-protein dysfunction
  description: >-
    In the distal arthrogryposis syndromes, heterozygous variants in genes
    encoding sarcomeric contractile proteins — embryonic myosin heavy chain
    (MYH3), beta-tropomyosin (TPM2), and fast skeletal troponin I (TNNI2) —
    disrupt actomyosin interactions in developing skeletal muscle. Functional
    studies indicate that these variants produce prolonged actomyosin binding
    and altered force generation, reducing effective fetal movement and
    producing congenital limb contractures.
  cell_types:
  - preferred_term: skeletal muscle fiber
    term:
      id: CL:0008002
      label: skeletal muscle fiber
  biological_processes:
  - preferred_term: muscle contraction
    modifier: ABNORMAL
    term:
      id: GO:0006936
      label: muscle contraction
  evidence:
  - reference: PMID:32799913
    reference_title: Drosophila myosin mutants model the disparate severity of type 1 and type 2B distal arthrogryposis and indicate an enhanced actin affinity mechanism.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The defects observed in our DA1 and DA2B Drosophila models provide insight into DA phenotypes in humans, suggesting that contractures arise from prolonged actomyosin interactions."
    explanation: >-
      The Drosophila DA1/DA2B myosin models directly support a prolonged
      actomyosin interaction mechanism in sarcomeric forms of AMC.
  - reference: PMID:32799913
    reference_title: Drosophila myosin mutants model the disparate severity of type 1 and type 2B distal arthrogryposis and indicate an enhanced actin affinity mechanism.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most common cause of DA is a mutation of the embryonic myosin heavy chain gene, MYH3."
    explanation: >-
      MYH3 is identified as the most common DA gene, supporting the centrality
      of sarcomeric myosin in distal AMC.
  downstream:
  - target: Decreased fetal movement
- name: Congenital joint contracture formation
  description: >-
    Persistent fetal hypokinesia prevents normal stretching of muscle and
    periarticular connective tissue, leading to fatty-fibrous replacement of
    muscle and fixed congenital contractures of two or more joints. The
    distribution and severity of contractures distinguishes AMC subtypes.
  cell_types:
  - preferred_term: skeletal muscle fiber
    term:
      id: CL:0008002
      label: skeletal muscle fiber
  biological_processes:
  - preferred_term: skeletal muscle tissue development
    modifier: ABNORMAL
    term:
      id: GO:0007519
      label: skeletal muscle tissue development
  evidence:
  - reference: PMID:24459070
    reference_title: Amyoplasia revisited.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Affected limbs had characteristic positions with fatty-fibrous replacement of muscle."
    explanation: >-
      The 560-patient Amyoplasia series directly documents fatty-fibrous muscle
      replacement underlying the contracture phenotype.
phenotypes:
- name: Congenital contracture
  category: Musculoskeletal
  description: >-
    Multiple fixed joint contractures present from birth are the defining
    clinical feature of AMC, by definition involving two or more different body
    areas.
  phenotype_term:
    preferred_term: Congenital contracture
    term:
      id: HP:0002803
      label: Congenital contracture
  evidence:
  - reference: PMID:38856159
    reference_title: Bi-allelic variants in MYH3 cause recessively-inherited arthrogryposis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Arthrogryposis is a clinical feature defined by congenital joint contractures in two or more different body areas which occurs in between 1/3000 and 1/5000 live births."
    explanation: >-
      Morali et al. provide the standard clinical definition of arthrogryposis
      as congenital joint contractures in two or more body areas.
- name: Limb joint contracture
  category: Musculoskeletal
  description: >-
    Contractures predominantly involve limb joints, with characteristic
    extended elbows and equinovarus foot positioning in Amyoplasia and
    predominant hand-and-foot involvement in distal arthrogryposis.
  phenotype_term:
    preferred_term: Limb joint contracture
    term:
      id: HP:0003121
      label: Limb joint contracture
  evidence:
  - reference: PMID:24459070
    reference_title: Amyoplasia revisited.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Upper limb involvement was usually characterized by extended elbows. Lower limbs were held in various positions at birth; however, equinovarus positioning of feet was almost always present."
    explanation: >-
      The Amyoplasia series documents characteristic limb-joint contracture
      positioning involving elbows and feet.
- name: Talipes equinovarus
  category: Musculoskeletal
  description: >-
    Clubfoot is one of the most consistent congenital limb-position deformities
    in AMC and is nearly universal in lower-limb Amyoplasia.
  phenotype_term:
    preferred_term: Talipes equinovarus
    term:
      id: HP:0001762
      label: Talipes equinovarus
  evidence:
  - reference: PMID:24459070
    reference_title: Amyoplasia revisited.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "equinovarus positioning of feet was almost always present"
    explanation: >-
      The Amyoplasia series directly reports near-universal equinovarus foot
      positioning at birth.
- name: Decreased fetal movement
  category: Prenatal
  description: >-
    Reduced or absent fetal movement detected prenatally or inferred from the
    contracture phenotype is the unifying mechanistic feature across AMC
    subtypes.
  phenotype_term:
    preferred_term: Decreased fetal movement
    term:
      id: HP:0001558
      label: Decreased fetal movement
  evidence:
  - reference: PMID:27587986
    reference_title: "Arthrogryposis as a Syndrome: Gene Ontology Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All types of arthrogryposis have decreased in utero fetal movement."
    explanation: >-
      Hall and Kiefer document decreased fetal movement as a shared feature
      across arthrogryposis types.
- name: Arthrogryposis multiplex congenita
  category: Musculoskeletal
  description: >-
    Multi-region congenital contractures define the AMC clinical syndrome and
    serve as the entry phenotype for the broader differential.
  phenotype_term:
    preferred_term: Arthrogryposis multiplex congenita
    term:
      id: HP:0002804
      label: Arthrogryposis multiplex congenita
  evidence:
  - reference: PMID:38856159
    reference_title: Bi-allelic variants in MYH3 cause recessively-inherited arthrogryposis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Arthrogryposis is a clinical feature defined by congenital joint contractures in two or more different body areas"
    explanation: >-
      Morali et al. supply the standard "two or more body areas" definition
      that aligns the AMC phenotype with HP:0002804.
genetic:
- name: Heterozygous MYH3 variants
  association: Causative
  gene_term:
    preferred_term: MYH3
    term:
      id: hgnc:7573
      label: MYH3
  notes: >-
    MYH3, encoding embryonic myosin heavy chain, is the most common single gene
    cause of distal arthrogryposis. Heterozygous variants cause Freeman-Sheldon
    syndrome (DA2A), Sheldon-Hall syndrome (DA2B), and multiple pterygium
    syndrome. Three recurrent MYH3 missense variants (p.T178I, p.R672C,
    p.R672H) account for the majority of DA2A cases.
  evidence:
  - reference: PMID:25256237
    reference_title: Genotype-phenotype relationships in Freeman-Sheldon syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "MYH3 mutations were found in 43/46 (93%) kindreds, with three mutations (p.T178I, p.R672C, and p.R672H) explaining 39/43 (91%) of cases."
    explanation: >-
      The Beck FSS series quantifies the dominance of three recurrent MYH3
      missense variants in DA2A.
  - reference: PMID:38856159
    reference_title: Bi-allelic variants in MYH3 cause recessively-inherited arthrogryposis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Heterozygous variants in MYH3 have been identified to cause the dominantly-inherited distal arthrogryposis conditions, Freeman-Sheldon syndrome, Sheldon-Hall syndrome, and multiple pterygium syndrome."
    explanation: >-
      Morali et al. enumerate the dominant MYH3-associated AMC syndromes.
- name: Heterozygous TPM2 variants
  association: Causative
  gene_term:
    preferred_term: TPM2
    term:
      id: hgnc:12011
      label: TPM2
  notes: >-
    TPM2 encodes beta-tropomyosin, a thin-filament regulatory protein of
    skeletal muscle sarcomeres. Heterozygous TPM2 variants cause distal
    arthrogryposis type 2B (Sheldon-Hall syndrome) and related distal
    arthrogryposis phenotypes.
  evidence:
  - reference: PMID:30285720
    reference_title: Novel mutations in TPM2 and PIEZO2 are responsible for distal arthrogryposis (DA) 2B and mild DA in two Chinese families.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A heterozygous missense mutation c.308A > G (p.Q103R) in TPM2 in Family 1"
    explanation: >-
      Li et al. directly demonstrate a heterozygous TPM2 missense variant
      segregating with DA2B in a multigenerational family.
- name: Heterozygous TNNI2 variants
  association: Associated
  gene_term:
    preferred_term: TNNI2
    term:
      id: hgnc:11946
      label: TNNI2
  notes: >-
    TNNI2 encodes fast skeletal troponin I, a sarcomeric thin-filament
    regulatory protein. TNNI2 is grouped with TPM2 in the thin-filament
    regulatory cluster of distal arthrogryposis candidate genes; the cited
    paper used TNNI2 as a linkage candidate locus alongside TPM2 in DA
    families but did not itself demonstrate a pathogenic TNNI2 variant.
    A dedicated TNNI2 causative-variant citation (e.g., Sung et al. 2003,
    PMID:12618959) should be added in a future revision to upgrade this
    association to `Causative`.
  evidence:
  - reference: PMID:30285720
    reference_title: Novel mutations in TPM2 and PIEZO2 are responsible for distal arthrogryposis (DA) 2B and mild DA in two Chinese families.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "two-point linkage analysis was performed with microsatellite markers closed to TPM2, TNNI2/TNNT3 and TNNC2"
    explanation: >-
      Li et al. include TPM2, TNNI2/TNNT3, and TNNC2 as established DA
      linkage candidate loci in their analysis, supporting TNNI2's
      inclusion in the DA thin-filament gene set; the paper does not
      itself demonstrate a causal TNNI2 variant (TPM2 was the causal gene
      in Family 1).
diagnosis:
- name: Clinical pattern recognition
  description: >-
    AMC is a clinical diagnosis based on congenital joint contractures in two
    or more body areas. Subtype assignment depends on the distribution of
    contractures, associated craniofacial and prenatal features, and family
    history. Amyoplasia in particular remains a clinical diagnosis.
  evidence:
  - reference: PMID:24459070
    reference_title: Amyoplasia revisited.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is a clinical diagnosis at this time."
    explanation: >-
      Hall et al. state that Amyoplasia is currently a clinical diagnosis.
- name: Exome or genome sequencing
  description: >-
    Molecular testing by exome or genome sequencing is used to identify the
    causative gene in the Mendelian forms of AMC and to distinguish them from
    sporadic Amyoplasia.
  evidence:
  - reference: PMID:38856159
    reference_title: Bi-allelic variants in MYH3 cause recessively-inherited arthrogryposis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Sequencing and deletion/duplication analysis of 169 other arthrogryposis genes yielded no other compelling candidate variants."
    explanation: >-
      Morali et al. illustrate routine use of broad arthrogryposis gene-panel /
      exome sequencing in AMC molecular diagnosis.
treatments:
- name: Early intensive physiotherapy
  description: >-
    Very early and aggressive physiotherapy in the neonatal and infant period
    is the foundation of AMC management and is associated with improved joint
    mobility and functional outcomes.
  treatment_term:
    preferred_term: physical therapy
    term:
      id: MAXO:0000011
      label: physical therapy
  target_phenotypes:
  - preferred_term: Limb joint contracture
    term:
      id: HP:0003121
      label: Limb joint contracture
  evidence:
  - reference: PMID:31479584
    reference_title: Treatment and outcomes of arthrogryposis in the lower extremity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The importance of very early and aggressive management of these deformities in the form of intensive physiotherapy (with its various modalities) and bracing is emphasized."
    explanation: >-
      The Shriners multiauthored review supports early aggressive physiotherapy
      and bracing as central AMC management.
- name: Bracing and orthotic management
  description: >-
    Orthotic bracing supports joint position and maintains range of motion
    achieved through physiotherapy and serial casting. Bracing is used across
    upper and lower extremity contractures and is integrated with surgical
    care.
  treatment_term:
    preferred_term: rehabilitation
    term:
      id: NCIT:C15315
      label: Rehabilitation
  target_phenotypes:
  - preferred_term: Limb joint contracture
    term:
      id: HP:0003121
      label: Limb joint contracture
  evidence:
  - reference: PMID:31479584
    reference_title: Treatment and outcomes of arthrogryposis in the lower extremity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Separate sections address various hip, knee, foot, and ankle issues as well as orthotic treatment and functional outcomes."
    explanation: >-
      The Shriners review devotes dedicated discussion to orthotic management
      across lower-limb joints in AMC.
- name: Orthopedic surgery for joint contractures
  description: >-
    Selective orthopedic surgical procedures — including soft-tissue release,
    osteotomies, gradual correction with external fixation, and selective
    quadriceps procedures for knee contractures — address residual contractures
    not corrected by physiotherapy and bracing.
  treatment_term:
    preferred_term: surgical procedure
    term:
      id: MAXO:0000004
      label: surgical procedure
  target_phenotypes:
  - preferred_term: Limb joint contracture
    term:
      id: HP:0003121
      label: Limb joint contracture
  evidence:
  - reference: PMID:22875688
    reference_title: Management of knee deformities in children with arthrogryposis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Surgical procedures vary with severity of contracture and patient age and include soft-tissue release, femoral shortening-extension osteotomy, gradual correction with Ilizarov, and femoral anterior epiphysiodesis."
    explanation: >-
      Lampasi et al. enumerate the standard orthopedic surgical procedures used
      to correct AMC knee contractures.
- name: Multidisciplinary care
  description: >-
    Care for individuals with AMC requires a coordinated multidisciplinary
    approach involving genetics, orthopedics, rehabilitation, and family
    stakeholders across the lifespan.
  treatment_term:
    preferred_term: supportive care
    term:
      id: MAXO:0000950
      label: supportive care
  evidence:
  - reference: PMID:31479584
    reference_title: Treatment and outcomes of arthrogryposis in the lower extremity.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The central role of a multidisciplinary approach involving all stakeholders, especially the families, is also discussed."
    explanation: >-
      The Shriners review emphasizes a multidisciplinary care model for AMC.
- name: Genetic counseling
  description: >-
    Genetic counseling addresses the wide heterogeneity of AMC, the sporadic
    nature of Amyoplasia, autosomal dominant or recessive recurrence risk in
    the Mendelian forms, and prenatal or preimplantation testing options.
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: MAXO:0000079
      label: genetic counseling
notes: >-
  AMC is an umbrella clinical phenotype rather than a single disease. This
  entry summarizes the shared fetal-akinesia mechanism and the major clinical
  groups (Amyoplasia, distal arthrogryposis, multiple pterygium syndromes,
  LCCS). Detailed gene-specific pathophysiology and management belong in
  dedicated subtype entries (e.g., Autosomal Recessive Multiple Pterygium
  Syndrome). Genetic heterogeneity is extensive, with more than 400 reported
  AMC-associated genes; only the three most informative distal-arthrogryposis
  thin- and thick-filament genes (MYH3, TPM2, TNNI2) are itemized here.
datasets:
📚

References & Deep Research

References

9
PMID:24459070
Amyoplasia revisited.
1 finding
Amyoplasia is the most common form of AMC, is sporadic, and shows characteristic symmetric limb positions with fatty-fibrous muscle replacement.
"Hall's large 560-patient series provides the canonical clinical description of Amyoplasia and supports the sporadic recurrence pattern."
PMID:24459095
Amyoplasia involving only the upper limbs or only involving the lower limbs with review of the relevant differential diagnoses.
No top-level findings curated for this source.
PMID:27587986
Arthrogryposis as a Syndrome: Gene Ontology Analysis.
1 finding
All forms of arthrogryposis share decreased in utero fetal movement as the unifying mechanism.
"Hall and Kiefer's GO-based reanalysis explicitly frames decreased fetal movement as the shared mechanistic pathway across genetic AMC subtypes."
PMID:25256237
Genotype-phenotype relationships in Freeman-Sheldon syndrome.
1 finding
Freeman-Sheldon syndrome (DA2A) is caused by MYH3 mutations and is the most severe of the distal arthrogryposis syndromes.
"Beck et al. characterized MYH3 genotype-phenotype relationships in 46 DA2A families, supporting DA2A classification and severity ranking among the DAs."
PMID:38856159
Bi-allelic variants in MYH3 cause recessively-inherited arthrogryposis.
1 finding
MYH3 underlies multiple dominantly inherited distal arthrogryposis syndromes including Freeman-Sheldon, Sheldon-Hall, and a multiple pterygium phenotype.
"Morali et al. summarize the dominant MYH3-associated AMC syndromes and extend the gene to recessive distal arthrogryposis."
PMID:30285720
Novel mutations in TPM2 and PIEZO2 are responsible for distal arthrogryposis (DA) 2B and mild DA in two Chinese families.
1 finding
TPM2 mutations cause distal arthrogryposis type 2B (Sheldon-Hall syndrome).
"Li et al. mapped a DA2B family to TPM2 and identified a pathogenic missense variant, supporting the TPM2-DA2B association."
PMID:32799913
Drosophila myosin mutants model the disparate severity of type 1 and type 2B distal arthrogryposis and indicate an enhanced actin affinity mechanism.
1 finding
Distal arthrogryposis contractures arise from prolonged actomyosin interactions in sarcomeric muscle.
"Guo et al. used Drosophila DA1 and DA2B myosin models to show that prolonged myosin-actin binding underlies the disparate severity of these DA forms."
PMID:31479584
Treatment and outcomes of arthrogryposis in the lower extremity.
1 finding
Early, intensive physiotherapy and bracing combined with selective surgery is the core management of AMC.
"The multiauthored Shriners review supports the centrality of early physiotherapy and orthopedic intervention in AMC management."
PMID:22875688
Management of knee deformities in children with arthrogryposis.
No top-level findings curated for this source.

Deep Research

1
Arthrogryposis Multiplex Congenita Deep Research Fallback ▸

Arthrogryposis Multiplex Congenita Deep Research Fallback

Provider Attempts

  • 2026-05-13: Automated deep-research providers (falcon, asta, cyberian-codex, perplexity, openai) were unavailable in the curation environment for this disorder. No provider-generated research artifact was produced.

No provider-generated research artifact was available to integrate. Curation therefore proceeded from a manual literature synthesis built around the canonical AMC clinical and molecular references listed below, without hand-editing any references_cache/*.md files.

Evidence Scope Used For Curation

  • PMID:24459070 (Hall JG, Amyoplasia revisited) — the canonical 560-patient Amyoplasia case series. Provides the foundational clinical description of Amyoplasia, supports its sporadic recurrence pattern, documents the characteristic symmetric limb positioning (extended elbows, equinovarus feet), and reports fatty-fibrous replacement of muscle. Used for the Amyoplasia subtype, the Sporadic inheritance entry, the Congenital contracture / Limb joint contracture / Talipes equinovarus phenotypes, and the Clinical pattern recognition diagnostic entry.
  • PMID:24459095 (Hall JG, Amyoplasia involving only the upper limbs or only the lower limbs) — complementary differential-diagnosis paper for Amyoplasia; included in references: as background for the Amyoplasia clinical group.
  • PMID:27587986 (Hall JG, Kiefer J, Arthrogryposis as a Syndrome: Gene Ontology Analysis) — synthesis paper explicitly framing decreased in utero fetal movement (fetal akinesia) as the shared mechanistic pathway across all genetic AMC subtypes. Anchors the "Decreased fetal movement" pathophysiology node and the Decreased fetal movement phenotype.
  • PMID:25256237 (Beck AE et al., Genotype-phenotype relationships in Freeman-Sheldon syndrome) — 46-family DA2A series. Establishes MYH3 as causative for Freeman-Sheldon syndrome (DA2A) and quantifies the three recurrent missense variants (p.T178I, p.R672C, p.R672H) that account for the majority of DA2A cases. Used for the Heterozygous MYH3 variants genetic entry.
  • PMID:38856159 (Morali et al., Bi-allelic variants in MYH3 cause recessively-inherited arthrogryposis) — extends MYH3 from a purely dominant gene (Freeman-Sheldon, Sheldon-Hall, multiple pterygium) to a recessive cause of distal arthrogryposis. Provides the standard "two-or-more body areas" clinical definition of arthrogryposis used in the Congenital contracture and Arthrogryposis multiplex congenita phenotype entries, the Autosomal recessive inheritance entry, and the Exome / genome sequencing diagnostic entry.
  • PMID:30285720 (Li B et al., Novel mutations in TPM2 and PIEZO2 are responsible for distal arthrogryposis (DA) 2B and mild DA in two Chinese families) — provides a heterozygous TPM2 missense variant segregating with DA2B (Sheldon-Hall syndrome) in a multigenerational family. Used for the Heterozygous TPM2 variants genetic entry. The same paper performs linkage analysis with markers at TPM2, TNNI2/TNNT3, and TNNC2, which is used as PARTIAL evidence for the Heterozygous TNNI2 variants entry (which carries an Associated association rather than Causative, pending addition of a dedicated TNNI2 causative-variant citation in a future revision).
  • PMID:32799913 (Guo P et al., Drosophila myosin DA1/DA2B models) — the mechanistic paper supporting prolonged actomyosin interactions as the proximal sarcomeric defect in DA1 and DA2B. Tagged with evidence_source: MODEL_ORGANISM for the sarcomeric contractile-protein dysfunction pathophysiology node and for the autosomal dominant inheritance characterization (their introduction frames the DAs as autosomal dominant skeletal muscle diseases).
  • PMID:31479584 (Shriners multiauthored review, Treatment and outcomes of arthrogryposis in the lower extremity) — anchors early intensive physiotherapy and bracing as the central, evidence-supported management for AMC, and emphasizes a multidisciplinary care model.
  • PMID:22875688 (Lampasi et al., Management of knee deformities in children with arthrogryposis) — enumerates the orthopedic surgical procedures (soft-tissue release, femoral shortening-extension osteotomy, Ilizarov gradual correction, femoral anterior epiphysiodesis) used to address residual knee contractures in AMC.

Literature Synthesis

Arthrogryposis Multiplex Congenita (AMC) is an umbrella clinical phenotype — defined by congenital joint contractures involving two or more different body areas — rather than a single disease (PMID:38856159). The condition is etiologically heterogeneous and includes more than 400 recognized genetic disorders together with the sporadic, classical form Amyoplasia (PMID:24459070). Across all forms, the most consistent unifying mechanistic feature is decreased in utero fetal movement: "All types of arthrogryposis have decreased in utero fetal movement." (PMID:27587986). Persistent fetal hypokinesia prevents normal stretching of muscle and periarticular connective tissue, producing fixed congenital contractures, fatty-fibrous replacement of muscle, characteristic limb positioning (extended elbows, equinovarus feet), and the broader fetal akinesia deformation sequence findings (PMID:24459070, PMID:27587986).

Clinically, AMC is divided into four major groups. Amyoplasia, the most common single form, is sporadic, "completely sporadic" in Hall's 560-patient series (PMID:24459070), and is characterized by symmetric severe limb contractures, fatty-fibrous muscle replacement, characteristic limb positioning, and typically preserved cognition; it remains "a clinical diagnosis at this time" (PMID:24459070). The distal arthrogryposis (DA) syndromes are typically autosomal dominant disorders preferentially affecting the hands and feet, including DA1, DA2A (Freeman-Sheldon, the most severe), and DA2B (Sheldon-Hall) (PMID:25256237, PMID:32799913). The multiple pterygium syndromes combine congenital contractures with pterygia across flexural joints and include the autosomal recessive Escobar variant and the lethal multiple pterygium syndrome. The lethal congenital contracture syndromes (LCCS) are prenatal- or perinatal-lethal disorders in the fetal akinesia deformation sequence spectrum.

Molecularly, the dominant DA syndromes are caused predominantly by heterozygous variants in genes encoding sarcomeric contractile proteins. MYH3 (embryonic myosin heavy chain) is the most common single gene cause: "Heterozygous variants in MYH3 have been identified to cause the dominantly-inherited distal arthrogryposis conditions, Freeman-Sheldon syndrome, Sheldon-Hall syndrome, and multiple pterygium syndrome." (PMID:38856159). In Beck et al.'s 46-family DA2A series, "MYH3 mutations were found in 43/46 (93%) kindreds, with three mutations (p.T178I, p.R672C, and p.R672H) explaining 39/43 (91%) of cases." (PMID:25256237). MYH3 also underlies a recessive form of distal arthrogryposis (PMID:38856159). Heterozygous TPM2 (beta-tropomyosin) variants cause DA2B and related distal arthrogryposis phenotypes (PMID:30285720). TNNI2 (fast skeletal troponin I) is grouped with TPM2 in the thin-filament regulatory cluster of distal arthrogryposis candidate loci (PMID:30285720); the present entry classifies TNNI2 with association: Associated and a PARTIAL evidence tag, because the Li et al. paper used TNNI2 as a linkage candidate locus rather than itself demonstrating a pathogenic TNNI2 variant. Functional Drosophila modeling demonstrates that DA1 and DA2B sarcomeric variants produce prolonged actomyosin interactions, which plausibly reduces effective fetal movement and produces the congenital contracture phenotype (PMID:32799913).

Management of AMC is lifelong and multidisciplinary, centered on early intensive physiotherapy and orthotic bracing: "The importance of very early and aggressive management of these deformities in the form of intensive physiotherapy (with its various modalities) and bracing is emphasized." (PMID:31479584). Selective orthopedic surgical procedures — soft-tissue release, femoral shortening-extension osteotomy, gradual correction with Ilizarov frames, and femoral anterior epiphysiodesis — address residual contractures not corrected by conservative measures (PMID:22875688). Care delivery emphasizes "the central role of a multidisciplinary approach involving all stakeholders, especially the families" (PMID:31479584). Genetic counseling is integral, given the sporadic nature of Amyoplasia and the autosomal dominant or recessive recurrence risks in the Mendelian forms.

Curation Conclusions

The accepted unifying model of AMC is decreased in utero fetal movement (fetal akinesia) producing fixed congenital joint contractures across two or more body areas. The mechanism is gene-agnostic at the level of the final common pathway, but converges from many proximal causes — most prominently sarcomeric contractile-protein dysfunction in the distal arthrogryposes (MYH3, TPM2, TNNI2). The dismech graph therefore models three pathophysiology nodes (decreased fetal movement, sarcomeric contractile-protein dysfunction, congenital joint contracture formation) linked by downstream edges that capture the conserved final-common pathway. Subtype assignment is clinically anchored (Amyoplasia, distal arthrogryposis, multiple pterygium syndromes, LCCS) and is informed by contracture distribution, associated craniofacial and prenatal features, and family history, with exome / genome sequencing used to identify causative Mendelian variants. Detailed gene-specific pathophysiology and management belong in dedicated subtype entries; the present entry itemizes only the most informative thin- and thick-filament DA genes (MYH3, TPM2, TNNI2).