Related Experiment Video
Updated: Jun 20, 2026
08:08
Chicken Recombinant Limbs Assay to Understand Morphogenesis, Patterning, and Early Steps in Cell Differentiation
Published on: January 12, 2022
Apical Ectodermal Ridge Disruption and Hypoplastic Digits in Amyoplasia
Amanda Stutman1, Natalie Williams1, Sarah Nossov1
1Shriners Children's Philadelphia, Philadelphia, Pennsylvania, USA.
Summary
Amyoplasia, a rare birth defect, may be linked to disruptions in the apical ectodermal ridge (AER). This finding suggests a potential new pathway for understanding limb malformations in affected infants.
Area of Science:
- Developmental Biology
- Pediatric Orthopedics
- Clinical Genetics
Background:
- Amyoplasia's etiology is debated, with vascular disruption of anterior horn cells being a leading theory.
- Disruption of the apical ectodermal ridge (AER) is exceptionally rare, contrasting with Amyoplasia's higher incidence.
- Muscle precursor cell differentiation relies on AER-dependent signaling factors in the limb.
Purpose of the Study:
- To investigate a potential association between apical ectodermal ridge (AER) disruption and Amyoplasia.
- To explore if AER dysfunction contributes to the pathogenesis of Amyoplasia.
- To identify characteristics of limb malformations in patients with Amyoplasia and hypodactyly.
Main Methods:
- Retrospective review of 22 patients diagnosed with Amyoplasia and at least one hypoplastic digit.
- Analysis of radiographs, clinical photographs, clinic notes, and operative reports.
- Exclusion of five patients due to incomplete data or unconfirmed diagnoses.
Main Results:
- Hypoplastic fingers were observed in 41% of cases, hypoplastic toes in 47%, and both in 6%.
- Limb malformations included foot loss in 6% of patients.
- No patient exhibited fully preserved ectoderm at amputation sites or evidence of amniotic bands.
Conclusions:
- Loss of AER function, leading to hypodactyly, may be a characteristic feature of Amyoplasia.
- A potential causal or downstream association exists between AER loss and impaired muscle development.
- This association offers a new perspective on the pathogenesis of Amyoplasia.
Related Concept Videos
03:14Notch Signaling Pathway
The Notch signaling pathway is a major intracellular signaling pathway that is highly conserved over a broad spectrum of metazoan species. It stands unique from other intracellular signaling mechanisms in animals because notch protein itself acts as the receptor as well as the primary signaling molecule.
The Notch gene came into the limelight in 1914 after the discovery that its mutation in Drosophila melanogaster leads to a serrated (or "notched") wing margin phenotype. It was not until 1985...
The Notch gene came into the limelight in 1914 after the discovery that its mutation in Drosophila melanogaster leads to a serrated (or "notched") wing margin phenotype. It was not until 1985...
02:30Genomic Imprinting and Inheritance
Diploid organisms inherit genetic material through chromosomes from both parents. Copies of the same gene are known as alleles. In most cases, both alleles are simultaneously expressed and allow various cellular processes to function optimally. If one of the alleles is missing or mutated, the expression of the other allele can compensate; however, this is not true for all genes.
The expression of some genes depends on which parent passed the gene to the offspring, through a phenomenon known as...
The expression of some genes depends on which parent passed the gene to the offspring, through a phenomenon known as...
01:09Changes in the Appendicular Skeleton with Age
The upper and lower limb initially develops as a small bulge called a limb bud, which appears on the lateral side of the early embryo. The upper limb bud appears near the end of the fourth week of development, with the lower limb bud appearing shortly after.
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
01:33Pleiotropy
Pleiotropy is the phenomenon in which a single gene impacts multiple, seemingly unrelated phenotypic traits. For example, defects in the SOX10 gene cause Waardenburg Syndrome Type 4, or WS4, which can cause defects in pigmentation, hearing impairments, and an absence of intestinal contractions necessary for elimination. This diversity of phenotypes results from the expression pattern of SOX10 in early embryonic and fetal development. SOX10 is found in neural crest cells that form melanocytes,...
01:09Cytoskeletal Linker Proteins - Plakins
Plakins are large proteins with binding domains for microtubules, microfilaments, intermediate filaments, and membrane-associated protein complexes at cell junctions. Plakin functions are evolutionarily conserved and are primarily involved in organizing the different components of the cytoskeleton by crosslinking them to each other and connecting them to the cell-matrix and cell adhesion complexes. They are also known to interact with signal transducers, serve as scaffolds for signaling...
02:33Hedgehog Signaling Pathway
The Hedgehog gene (Hh) was first discovered due to its control of the growth of disorganized, hair-like bristles phenotype in Drosophila, much like hedgehog spines. Hh plays a crucial role in the development of organs and the maintenance of homeostasis in both invertebrates and vertebrates. However, while Drosophila has only one Hh protein, mammals have multiple functional Hedgehog proteins - Sonic (Shh), Desert (Dhh), and Indian Hedgehog (Ihh). All of these homologous proteins have adapted to...