Cyclopia | |
---|---|
Other names | Cyclocephaly, synophthalmia |
Fetuses with cyclopia | |
Specialty | Medical genetics |
Usual onset | During embryonic development |
Duration | Lifelong |
Prognosis | Always fatal within a day |
Frequency | 1 in 100,000 births |
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 orbits of the eye into two cavities. Its incidence is 1 in 16,000 in born animals and 1 in 200 in miscarried fetuses. [1] [2]
Typically, the nose is either missing or not functional. This deformity (called proboscis) forms above the center eye and is characteristic of a form of cyclopia called rhinencephaly or rhinocephaly. [3] Most such embryos are either naturally miscarried or are stillborn upon delivery.
Although cyclopia is rare, several cyclopic human babies are preserved in medical museums (e.g. The Vrolik Museum, Amsterdam, Trivandrum Medical College). [4]
Some extreme cases of cyclopia have been documented in farm animals (horses, sheep, pigs, goats, and sometimes chickens). In such cases, the nose and mouth fail to form, or the nose grows from the roof of the mouth, obstructing airflow and resulting in suffocation shortly after birth. [5]
Genetic defects or toxins can misdirect the embryonic forebrain-dividing process. [6] One highly teratogenic alkaloid toxin that can cause cyclopia is cyclopamine or 2-deoxyjervine, found in the plant Veratrum californicum (also known as corn lily or false hellebore). Grazing animals are most likely to ingest this plant and induce cyclopia in offspring. People sometimes accidentally ingest false hellebore while pregnant thinking it is hellebore, which has been suggested as a "natural" treatment for vomiting, cramps, and poor circulation – three conditions which may be present in the early stages of pregnancy. [7] Cyclopia occurs when certain proteins are inappropriately expressed, [8] causing the brain to stay whole, rather than developing two distinct hemispheres. This leads to the fetus having one optic lobe and one olfactory lobe, resulting in the eye and nose malformations of cyclopia. [9]
The Sonic Hedgehog (SHH) gene regulator is involved in the separation of the single eye field into two bilateral fields. [10] Although not proven, it is thought that SHH emitted from the prechordal plate suppresses Pax6, which causes the eye field to divide into two. If the SHH gene is mutated, the result is cyclopia, a single eye in the center of the face (Gilbert, 2000).
First, That it had no sign of any Nose in the usual place, nor had it any, in any other place of the Head, unless the double Bagg CC that grew out of the midst of the forehead, were some rudiment of it. Next, That the two Eyes were united into one Double Eye which was placed just in the middle of the Brow. [11]
The Islamic State of Iraq and the Levant used photos of babies born with cyclopia in its recruitment campaign. ISIL claimed the photos depicted Masih ad-Dajjal, who according to the Hadith, would have only one eye. Mainstream Islamic scholars consider the prophecy as referring to a one-eyed man, not a cyclops. [26] One infant whose image was circulated in 2014 was claimed to be Israeli, but was actually Bolivian and from 2008. The baby girl from India born in 2006 (see notable cases above) also had her image used. [27]
Holoprosencephaly (HPE) is a cephalic disorder in which the prosencephalon fails to develop into two 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.
Cebocephaly 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. 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.
Sonic hedgehog protein (SHH) is encoded for by the SHH gene. The protein is named after the video game character Sonic the Hedgehog.
Patau syndrome is a syndrome caused by a chromosomal abnormality, in which some or all of the cells of the body contain extra genetic material from chromosome 13. The extra genetic material disrupts normal development, causing multiple and complex organ defects.
Congenital syphilis is syphilis that occurs when a mother with untreated syphilis passes the infection to her baby during pregnancy or at birth. It may present in the fetus, infant, or later. Clinical features vary and differ between early onset, that is presentation before 2-years of age, and late onset, presentation after age 2-years. Infection in the unborn baby may present as poor growth, non-immune hydrops leading to premature birth or loss of the baby, or no signs. Affected newborns mostly initially have no clinical signs. They may be small and irritable. Characteristic features include a rash, fever, large liver and spleen, a runny and congested nose, and inflammation around bone or cartilage. There may be jaundice, large glands, pneumonia, meningitis, warty bumps on genitals, deafness or blindness. Untreated babies that survive the early phase may develop skeletal deformities including deformity of the nose, lower legs, forehead, collar bone, jaw, and cheek bone. There may be a perforated or high arched palate, and recurrent joint disease. Other late signs include linear perioral tears, intellectual disability, hydrocephalus, and juvenile general paresis. Seizures and cranial nerve palsies may first occur in both early and late phases. Eighth nerve palsy, interstitial keratitis and small notched teeth may appear individually or together; known as Hutchinson's triad.
Fetal viability is the ability of a human fetus to survive outside the uterus. Viability depends upon factors such as birth weight, gestational age, and the availability of advanced medical care. In low-income countries, more than 90% of extremely preterm newborns die due to a lack of said medical care; in high-income countries, the vast majority of these newborns survive.
Diprosopus, also known as craniofacial duplication, is an extremely rare congenital disorder whereby parts (accessories) or all of the face are duplicated on the head.
Otocephaly, also known as agnathia–otocephaly complex, is a very rare and lethal cephalic disorder characterized by the absence of the mandible (agnathia), with the ears fused together just below the chin (synotia). It is caused by a disruption to the development of the first branchial arch. It occurs in every 1 in 70,000 embryos.
Cyclopamine (11-deoxojervine) is a naturally occurring steroidal alkaloid. It is a teratogenic component of corn lily, which when consumed during gestation has been demonstrated to induce birth defects, including the development of a single eye (cyclopia) in offspring. The molecule was named after this effect, which was originally observed by Idaho lamb farmers in 1957 after their herds gave birth to cycloptic lambs. It then took more than a decade to identify corn lily as the culprit. Later work suggested that differing rain patterns had changed grazing behaviours, which led to a greater quantity of corn lily to be ingested by pregnant sheep. Cyclopamine interrupts the sonic hedgehog signalling pathway, instrumental in early development, ultimately causing birth defects.
The Hedgehog signaling pathway is a signaling pathway that transmits information to embryonic cells required for proper cell differentiation. Different parts of the embryo have different concentrations of hedgehog signaling proteins. The pathway also has roles in the adult. Diseases associated with the malfunction of this pathway include cancer.
Arrhinia 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.
Anophthalmia is the medical term for the absence of one or both eyes. Both the globe and the ocular tissue are missing from the orbit. The absence of the eye will cause a small bony orbit, a constricted mucosal socket, short eyelids, reduced palpebral fissure and malar prominence. Genetic mutations, chromosomal abnormalities, and prenatal environment can all cause anophthalmia. Anophthalmia is an extremely rare disease and is mostly rooted in genetic abnormalities. It can also be associated with other syndromes.
Veratrum californicum is an extremely poisonous plant native to western North America, including the Sierra Nevada and Rocky Mountains, as far north as Washington and as far south as Durango; depending on latitude, it grows from near sea level to as high as 11,000 feet. It grows 1 to 2 meters tall, with an erect, unbranched, heavily leafy stem resembling a cornstalk. It prefers quite moist soil, and can cover large areas in dense stands near streams or in wet meadows. Many inch-wide flowers cluster along the often-branched top of the stout stem; they have 6 white tepals, a green center, 6 stamens, and a 3-branched pistil. The buds are tight green spheres. The heavily veined, bright green leaves can be more than a foot long.
Acrania is a rare congenital disorder that occurs in the human fetus in which the flat bones in the cranial vault are either completely or partially absent. The cerebral hemispheres develop completely but abnormally. The condition is frequently, though not always, associated with anencephaly. The fetus is said to have acrania if it meets the following criteria: the fetus should have a perfectly normal facial bone, a normal cervical column but without the fetal skull and a volume of brain tissue equivalent to at least one-third of the normal brain size.
A fetus or foetus is the unborn mammalian offspring that develops from an embryo. Following the embryonic stage, the fetal stage of development takes place. Prenatal development is a continuum, with no clear defining feature distinguishing an embryo from a fetus. However, in general a fetus is characterized by the presence of all the major body organs, though they will not yet be fully developed and functional, and some may not yet be situated in their final anatomical location.
A Child Is Born is a 1965 photographic book by Swedish photojournalist Lennart Nilsson. The book consists of photographs charting the development of the human embryo and fetus from conception to birth; it is reportedly the best-selling illustrated book ever published. Nilsson's photographs are accompanied by text, written by doctors, describing prenatal development and offering advice on antenatal care. The images were among the first of developing fetuses to reach a wide popular audience. Their reproduction in the April 30, 1965, edition of Life magazine sparked so much interest that the entire print run of eight million copies sold out within four days; they won Nilsson the American National Press Association Picture of the Year award, and reached a sufficiently iconic status to be chosen for launch into space aboard the NASA probes Voyager 1 and Voyager 2. The book and its images have figured in debates about abortion and the beginning of life, and the book is the subject of a substantial body of feminist critique.
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.
Young–Madders syndrome, alternatively known as Pseudotrisomy 13 syndrome or holoprosencephaly–polydactyly syndrome, is a genetic disorder resulting from defective and duplicated chromosomes which result in holoprosencephaly, polydactyly, facial malformations and intellectual disability, with a significant variance in the severity of symptoms being seen across known cases. Many cases often suffer with several other genetic disorders, and some have presented with hypoplasia, cleft lip, cardiac lesions and other heart defects. In one case in 1991 and another in 2000 the condition was found in siblings who were the product of incest. Many cases are diagnosed prenatally and often in siblings. Cases are almost fatal in the prenatal stage with babies being stillborn.
The Garbha Upanishad, or Garbhopanishad, is one of the minor Upanishads, listed number 17 in the modern anthology of 108 Hindu Upanishadic texts. Written in Sanskrit, it is associated with the Krishna Yajurveda by some, and as a Vedantic Upanishad associated with the Atharvaveda by other scholars. It is considered one of the 35 Samanya (general) Upanishads. The last verse of the Upanishad attributes the text to sage Pippalada, but the chronology and author of the text is unclear, and the surviving manuscripts are damaged, inconsistent with each other and incomplete.
XK aprosencephaly is an extremely rare congenital disorder characterized by the absence of the embryonic forebrain. Because the prosencephalon gives way to the cerebral cortex, survival with aprosencephaly is not possible outside utero. The external symptoms are similar to holoprosencephaly, a related disorder, including a smaller than normal head (microcephaly), small eyeballs (microphthalmia), a small mouth (microstomia), anal atresia, and abnormalities of the external genitalia, radius, nostrils, and pharynx (throat).
Media related to Cyclopia (medicine) at Wikimedia Commons