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First Arch Syndrome
First arch syndromes are congenital defects caused by a failure of neural crest cells to migrate into the first pharyngeal arch.Ronald W. Dudek. High-Yield Embryology. 2e. Page 65. They can produce facial anomalies. Examples of first arch syndromes include Treacher Collins syndrome and Pierre Robin syndrome Pierre Robin sequence (; abbreviated PRS) is a congenital defect observed in humans which is characterized by facial abnormalities. The three main features are micrognathia (abnormally small mandible), which causes glossoptosis (downwardly displac .... References Congenital disorders Syndromes Pharyngeal arches {{congenital-malformation-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congenital Defects
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth defects are divided into two main types: structural disorders in which problems are seen with the shape of a body part and functional disorders in which problems exist with how a body part works. Functional disorders include metabolic and degenerative disorders. Some birth defects include both structural and functional disorders. Birth defects may result from genetic or chromosomal disorders, exposure to certain medications or chemicals, or certain infections during pregnancy. Risk factors include folate deficiency, drinking alcohol or smoking during pregnancy, poorly controlled diabetes, and a mother over the age of 35 years old. Many are believed to involve multiple factors. Birth defects may be visib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neural Crest
Neural crest cells are a temporary group of cells unique to vertebrates that arise from the embryonic ectoderm germ layer, and in turn give rise to a diverse cell lineage—including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons and glia. After gastrulation, neural crest cells are specified at the border of the neural plate and the non-neural ectoderm. During neurulation, the borders of the neural plate, also known as the neural folds, converge at the dorsal midline to form the neural tube. Subsequently, neural crest cells from the roof plate of the neural tube undergo an epithelial to mesenchymal transition, delaminating from the neuroepithelium and migrating through the periphery where they differentiate into varied cell types. The emergence of neural crest was important in vertebrate evolution because many of its structural derivatives are defining features of the vertebrate clade. Underlying the development of neural crest is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
First Pharyngeal Arch
The pharyngeal arches, also known as visceral arches'','' are structures seen in the embryonic development of vertebrates that are recognisable precursors for many structures. In fish, the arches are known as the branchial arches, or gill arches. In the human embryo, the arches are first seen during the fourth week of development. They appear as a series of outpouchings of mesoderm on both sides of the developing pharynx. The vasculature of the pharyngeal arches is known as the aortic arches. In fish, the branchial arches support the gills. Structure In vertebrates, the pharyngeal arches are derived from all three germ layers (the primary layers of cells that form during embryogenesis). Neural crest cells enter these arches where they contribute to features of the skull and facial skeleton such as bone and cartilage. However, the existence of pharyngeal structures before neural crest cells evolved is indicated by the existence of neural crest-independent mechanisms of pharyng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congenital Anomaly
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth defects are divided into two main types: structural disorders in which problems are seen with the shape of a body part and functional disorders in which problems exist with how a body part works. Functional disorders include metabolic and degenerative disorders. Some birth defects include both structural and functional disorders. Birth defects may result from genetic or chromosomal disorders, exposure to certain medications or chemicals, or certain infections during pregnancy. Risk factors include folate deficiency, drinking alcohol or smoking during pregnancy, poorly controlled diabetes, and a mother over the age of 35 years old. Many are believed to involve multiple factors. Birth defects may be visib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Treacher Collins Syndrome
Treacher Collins syndrome (TCS) is a genetic disorder characterized by deformities of the ears, eyes, cheekbones, and chin. The degree to which a person is affected, however, may vary from mild to severe. Complications may include breathing problems, problems seeing, cleft palate, and hearing loss. Those affected generally have normal intelligence. TCS is usually autosomal dominant. More than half the time it occurs as a result of a new mutation rather than being inherited from a person's parents. The involved genes may include ''TCOF1'', ''POLR1C'', or ''POLR1D''. Diagnosis is generally suspected based on symptoms and X-rays, and potentially confirmation by genetic testing. Treacher Collins syndrome is not curable. Symptoms may be managed with reconstructive surgery, hearing aids, speech therapy, and other assistive devices. Life expectancy is generally normal. TCS occurs in about one in 50,000 people. The syndrome is named after Edward Treacher Collins, an English surgeon an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pierre Robin Syndrome
Pierre Robin sequence (; abbreviated PRS) is a congenital defect observed in humans which is characterized by facial abnormalities. The three main features are micrognathia (abnormally small mandible), which causes glossoptosis (downwardly displaced or retracted tongue), which in turn causes breathing problems due to obstruction of the upper airway. A wide, U-shaped cleft palate is commonly also present. PRS is not merely a syndrome, but rather it is a sequence—a series of specific developmental malformations which can be attributed to a single cause. Signs and symptoms PRS is characterized by an unusually small mandible, posterior displacement or retraction of the tongue, and upper airway obstruction. Cleft palate (incomplete closure of the roof of the mouth) is present in the majority of patients. Hearing loss and speech difficulty are often associated with PRS. Causes Mechanical basis The physical craniofacial deformities of PRS may be the result of a mechanical problem in w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congenital Disorders
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth defects are divided into two main types: structural disorders in which problems are seen with the shape of a body part and functional disorders in which problems exist with how a body part works. Functional disorders include metabolic and degenerative disorders. Some birth defects include both structural and functional disorders. Birth defects may result from genetic or chromosomal disorders, exposure to certain medications or chemicals, or certain infections during pregnancy. Risk factors include folate deficiency, drinking alcohol or smoking during pregnancy, poorly controlled diabetes, and a mother over the age of 35 years old. Many are believed to involve multiple factors. Birth defects may be vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syndromes
A syndrome is a set of medical signs and symptoms which are correlated with each other and often associated with a particular disease or disorder. The word derives from the Greek σύνδρομον, meaning "concurrence". When a syndrome is paired with a definite cause this becomes a disease. In some instances, a syndrome is so closely linked with a pathogenesis or cause that the words ''syndrome'', ''disease'', and ''disorder'' end up being used interchangeably for them. This substitution of terminology often confuses the reality and meaning of medical diagnoses. This is especially true of inherited syndromes. About one third of all phenotypes that are listed in OMIM are described as dysmorphic, which usually refers to the facial gestalt. For example, Down syndrome, Wolf–Hirschhorn syndrome, and Andersen–Tawil syndrome are disorders with known pathogeneses, so each is more than just a set of signs and symptoms, despite the ''syndrome'' nomenclature. In other instances, a syn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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