Shah–Waardenburg Syndrome
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Shah–Waardenburg Syndrome
Waardenburg syndrome type 4A is an extremely rare congenital disorder caused by a mutation in an endothelin receptor gene. It results in common Waardenburg syndrome symptoms such as abnormal hair and skin pigmentation and heterochromia, but also present with symptoms of Hirschsprung's disease. Symptoms include abdominal pain and bowel obstruction. Waardenburg syndrome type 4A is the rarest among the types, appearing only once in about every 1,000,000 individuals. There have only been a total of 50 cases reported in total as of 2016. Presentation Similar to other types of Waardenburg syndrome, Shah-Waardenburg syndrome patients present with some facial features such the abnormal pigmentation in the hair and premature graying, observed as white forelock. Their eyes also present abnormal pigmentation such as heterochromia iridis or uncharacteristic blue eyes. The study conducted by Shah reported additional physical features such as white eyebrows and eyelashes as well, which is no ...
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Heterochromia Iridum
Heterochromia is a variation in coloration most often used to describe color differences of the iris, but can also be applied to color variation of hair or skin. Heterochromia is determined by the production, delivery, and concentration of melanin (a pigment). It may be inherited, or caused by genetic mosaicism, chimerism, disease, or injury. It occurs in humans and certain breeds of domesticated animals. Heterochromia of the eye is called heterochromia iridum (heterochromia between the two eyes) or heterochromia iridis (heterochromia within one eye). It can be complete, sectoral, or central. In complete heterochromia, one iris is a different color from the other. In sectoral heterochromia, part of one iris is a different color from its remainder. In central heterochromia, there is a ring around the pupil or possibly spikes of different colors radiating from the pupil. Though multiple causes have been posited, the scientific consensus is that a lack of genetic diversity is t ...
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Hirschsprung's Disease
Hirschsprung's disease (HD or HSCR) is a birth defect in which nerves are missing from parts of the intestine. The most prominent symptom is constipation. Other symptoms may include vomiting, abdominal pain, diarrhea and slow growth. Most children develop signs and symptoms shortly after birth. However, others may be diagnosed later in infancy or early childhood. About half of all children with Hirschsprung's disease are diagnosed in the first year of life. Complications may include enterocolitis, megacolon, bowel obstruction and intestinal perforation. The disorder may occur by itself or in association with other genetic disorders such as Down syndrome or Waardenburg syndrome. About half of isolated cases are linked to a specific genetic mutation, and about 20% occur within families. Some of these occur in an autosomal dominant manner. The cause of the remaining cases is unclear. If otherwise normal parents have one child with the condition, the next child has a 4% risk o ...
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Waardenburg Syndrome Type 1 (3)
Waardenburg syndrome type 1 is a congenital disorder that caused by a mutation in the PAX3 gene that results in abnormal development in the neural crest during early development. Type 1 results in early graying and white forelock and a notable distance between the eyes, noted as dystopia canthorum. Common symptoms of the disease also includes non-progressive hearing loss in majority of patients with type 1. Patients can display complete or partial heterochromia and hypoplastic blue irides and congenital leukoderma. Presentation Type 1 of the Waardenburg syndrome's notable feature is dystopia canthorum. Along with this feature, some patients' eyelids are fused medially, resulting in medial sclerae. Inferior lachrymal is moved laterally, along with punctae opposite of the cornea. Other features include high and broad nasal root and also nasi hypoplasia. A squared jaw is reported in some patients. Others present with spina bifida due to the mutation in the neural crest during e ...
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Endothelin B Receptor
Endothelin receptor type B, (ET-B) is a protein that in humans is encoded by the ''EDNRB'' gene. Function Endothelin receptor type B is a G protein-coupled receptor which activates a phosphatidylinositol-calcium second messenger system. Its ligand, endothelin, consists of a family of three potent vasoactive peptides: ET1, ET2, and ET3. A splice variant, named SVR, has been described; the sequence of the ETB-SVR receptor is identical to ETRB except for the intracellular C-terminal domain. While both splice variants bind ET1, they exhibit different responses upon binding which suggests that they may be functionally distinct. Regulation In melanocytic cells the EDNRB gene is regulated by the microphthalmia-associated transcription factor. Mutations in either gene are links to Waardenburg syndrome. Clinical significance The multigenic disorder, Hirschsprung disease type 2, is due to mutation in endothelin receptor type B gene. Animals In horses, a mutation in the mid ...
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Aganglionosis
Hirschsprung's disease (HD or HSCR) is a birth defect in which nerves are missing from parts of the intestine. The most prominent symptom is constipation. Other symptoms may include vomiting, abdominal pain, diarrhea and slow growth. Most children develop signs and symptoms shortly after birth. However, others may be diagnosed later in infancy or early childhood. About half of all children with Hirschsprung's disease are diagnosed in the first year of life. Complications may include enterocolitis, megacolon, bowel obstruction and intestinal perforation. The disorder may occur by itself or in association with other genetic disorders such as Down syndrome or Waardenburg syndrome. About half of isolated cases are linked to a specific genetic mutation, and about 20% occur within families. Some of these occur in an autosomal dominant manner. The cause of the remaining cases is unclear. If otherwise normal parents have one child with the condition, the next child has a 4% risk of bei ...
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Development Of The Neural Tube
Development or developing may refer to: Arts *Development (music), the process by which thematic material is reshaped *Photographic development *Filmmaking, development phase, including finance and budgeting *Development hell, when a project is stuck in development *Development (band), English progressive pop rock band * ''Development'' (album), a 2002 album by Nonpoint Business *Business development, a process of growing a business *Career development *Corporate development, a position in a business *Energy development, activities concentrated on obtaining energy from natural resources *Green development, a real estate concept that considers social and environmental impact of development *Land development, altering the landscape in any number of ways *Land development bank, a kind of bank in India *Leadership development *New product development *Organization development *Professional development *Real estate development *Research and development *Training and development *F ...
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