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Proboscis (anomaly)
In teratology, a proboscis is a blind-ended, tube-like structure, commonly located in the middle of the face. It is commonly seen in severe forms of holoprosencephaly that include cyclopia and is usually the result of abnormal development of the nose. Types Proboscis formation is classified in four general types: holoprosencephalic proboscis, lateral nasal proboscis, supernumerary probosci, and disruptive proboscis. Holoprosencephalic proboscis A holoprosencephalic proboscis is found in holoprosencephaly (a condition in which the forebrain of the embryo fails to develop into two hemispheres as it should). In cyclopia or ethmocephaly, proboscis is an abnormally formed nose. In cyclopia Cyclopia (named after the Greek mythology characters cyclopes), also known as alobar holoprosencephaly, is the most extreme form of holoprosencephaly and is a congenital disorder (birth defect) characterized by the failure of the embryonic prosen ..., a single eye in the middle of the face ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teratology
Teratology is the study of abnormalities of physiological development in organisms during their life span. It is a sub-discipline in medical genetics which focuses on the classification of congenital abnormalities in dysmorphology caused by teratogens and also in pharmacology and toxicology. Teratogens are substances that may cause non-heritable birth defects via a toxic effect on an embryo or fetus. Defects include malformations, disruptions, deformations, and dysplasia that may cause stunted growth, delayed mental development, or other congenital disorders that lack structural malformations. These defects can be recognized prior to or at birth as well as later during early childhood. The related term developmental toxicity includes all manifestations of abnormal development that are caused by environmental insult. The extent to which teratogens will impact an embryo is dependent on several factors, such as how long the embryo has been exposed, the stage of development the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holoprosencephaly
Holoprosencephaly (HPE) is a cephalic disorder in which the prosencephalon (the forebrain of the embryo) fails to Prenatal development, develop into two Cerebral hemisphere, hemispheres, typically occurring between the 18th and 28th day of gestation. Normally, the forebrain is formed and the face begins to develop in the fifth and sixth weeks of human pregnancy. The condition also occurs in other species. Holoprosencephaly is estimated to occur in approximately 1 in every 250 conceptions; most cases are not compatible with life and result in fetal death Uterus, in utero due to deformities to the skull and brain. However, holoprosencephaly is still estimated to occur in approximately 1 in every 8,000 live births. When the embryo's forebrain does not divide to form bilateral cerebral hemispheres (the left and right halves of the brain), it causes Congenital abnormality, defects in the development of the face and in brain structure and function. The severity of holoprosencephaly is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopia
Cyclopia (named after the Greek mythology characters cyclopes), also known as alobar holoprosencephaly, is the most extreme form of holoprosencephaly and is a congenital disorder (birth defect) characterized by the failure of the embryonic prosencephalon to properly divide the Orbit (anatomy), orbits of the eye into two cavities. Its incidence is 1 in 16,000 in born animals and 1 in 200 in miscarriage, miscarried fetuses. Signs and symptoms Typically, the nose is either missing or not functional. This deformity (called Proboscis (anomaly), proboscis) forms above the center eye and is characteristic of a form of cyclopia called rhinencephaly or rhinocephaly. Most such embryos are either naturally miscarriage, miscarried or are stillbirth, stillborn upon childbirth, delivery. Although cyclopia is rare, several cyclopic human babies are preserved in medical museums (e.g. The University of Amsterdam, Vrolik Museum, Amsterdam, Trivandrum Medical College). Some extreme cases of cycl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arrhinia
Arrhinia (alternatively spelled "arhinia") is the congenital partial or complete absence of the nose at birth. It is an extremely rare condition, with few reported cases in the history of modern medicine. It is generally classified as a craniofacial abnormality. The cause of arrhinia is not known. One study of the literature found that all cases had presented a normal antenatal history. Conditions Arrhinia is associated with the following conditions and syndromes: * Arrhinia with choanal atresia and microphthalmia syndrome (Bosma arhinia microphthalmia syndrome) * Holoprosencephaly 1 * Holoprosencephaly 13, X-linked * Holoprosencephaly-radial heart renal anomalies syndrome History The phenomenon of congenital arrhinia, which refers to the complete absence of the nose from birth, was initially documented in French literature during the 1800s. Over time, a few additional cases of individuals born with congenital arrhinia, some with accompanying eye defects and others without ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethmocephaly
Ethmocephaly is a type of cephalic disorder caused by holoprosencephaly. Ethmocephaly is the rarest phenotypic variant of a group of defects called the holoprosencephaly (HPE) malformation sequence; other variants include cebocephaly, cyclopia, and median cleft palate. It consists of a proboscis separating narrow-set eyes with an absent nose and microphthalmia (abnormal smallness of one or both eyes). Cebocephaly, another facial anomaly, is characterized by a small, flattened nose with a single nostril situated below incomplete or underdeveloped closely set eyes. The least severe in the spectrum of facial anomalies is the median cleft lip, also called premaxillary agenesis. Although the causes of most cases of holoprosencephaly remain unknown, some may be due to dominant or chromosome causes. Such chromosomal anomalies as trisomy 13 and trisomy 18 have been found in association with holoprosencephaly, or other neural tube defects. Genetic counseling and genetic testing, such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cebocephaly
Cebocephaly (from Greek ''kebos'', "monkey" + ''kephale'', "head") is a developmental anomaly that is part of a group of defects called holoprosencephaly. Cebocephaly involves the presence of two separate eyes set close together and a small, flat nose with a single nostril (no nasal septum). It may be diagnosed before or after birth. It has a very poor prognosis, with most affected infants dying soon after birth. It is very rare, having been estimated to affect around 1 in 40,000 deliveries. Signs and symptoms Cebocephaly causes: * two separate eyes set close together * a small, flat nose with a single nostril * ear abnormalities * mouth abnormalities (such as microstomia) The presence of a nasal septum precludes a diagnosis of cebocephaly. Cebocephaly may cause malformations of the sphenoid and ethmoid bones behind the orbit. Cause Cebocephaly can be caused by many factors, particularly genetic variations. These include 18p-, 14q deletion, 13q deletion, and some vertic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
