Agenesis of the Corpus Callosum (ACC) is a rare birth defect (congenital disorder) in which there is a complete or partial absence of the corpus callosum. Agenesis of the corpus callosum occurs when the corpus callosum, the band of tissue connecting the two hemispheres of the brain, fails to develop normally, typically in utero, resulting in disconnected brain hemispheres. The development of the fibers which would otherwise form the corpus callosum become longitudinally orientated within each hemisphere and form structures called Probst Bundles. Image File history File links No higher resolution available. ... Link rot is the process by which links on a website gradually become irrelevant or broken as time goes on, because websites that they link to disappear, change their content or redirect to new locations. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... The Disease Bold textDatabase is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... eMedicine is an online clinical medical knowledge base that was founded in 1996. ... A congenital disorder is any medical condition that is present at birth. ... The corpus callosum is a structure of the mammalian brain in the longitudal fissure that connects the left and right cerebral hemispheres. ...

In addition to agenesis of the corpus callosum, other callosal disorders include hypogenesis (partial formation), dysgenesis (malformation) of the corpus callosum, and hypoplasia (underdevelopment) of the corpus callosum. ^[1]

Diagnosis

Callosal disorders can only be diagnosed through a brain scan. ^[2] They may be diagnosed through an MRI, CT Scan, prenatal ultrasound, or prenatal MRI. ^[3] The mri are a fictional alien species in the Faded Sun Trilogy of C.J. Cherryh. ... CAT apparatus in a hospital Computed axial tomography (CAT), computer-assisted tomography, computed tomography, CT, or body section roentgenography is the process of using digital processing to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around...

Cause

Agenesis of the Corpus Callosum is caused by disruption to development of the fetal brain between the 5th and 16th week of pregnancy.^[4] In most cases, it is not possible to know what caused an individual to have ACC or another callosal disorder. However, research suggests that some possible causes may include chromosome errors, inherited genetic factors, prenatal infections or injuries, prenatal toxic exposures, structural blockage by cysts or other brain abnormalities, and metabolic disorders. ^[5].

Relation to other rare disorders: genetic ciliopathy

Until recently, the medical literature did not indicate a connection among many genetic disorders, both genetic syndromes and genetic diseases, that are now being found to be related. As a result of new genetic research, some of these are, in fact, highly related in their root cause despite the widely-varying set of medical symptoms that are clinically visible in the disorders. Agenesis of the corpus callosum is one such disease, part of an emerging class of diseases called cilopathies. The underlying cause may be a dysfunctional molecular mechanism in the primary cilia structures of the cell, organelles which are present in many cellular types throughout the human body. The cilia defects adversely affect "numerous critical developmental signaling pathways" essential to cellular development and thus offer a plausible hypothesis for the often multi-symptom nature of a large set of syndromes and diseases. Known ciliopathies include primary ciliary dyskinesia, Bardet-Biedl syndrome, polycystic kidney and liver disease, nephronophthisis, Alstrom syndrome, Meckel-Gruber syndrome and some forms of retinal degeneration.^[6]. A genetic disorder is a condition caused by abnormalities in genes or chromosomes. ... In medicine, the term syndrome is the association of several clinically recognizable features, signs, symptoms, phenomena or characteristics which often occur together, so that the presence of one feature alerts the physician to the presence of the others. ... This article is about the medical term. ... This article does not cite any references or sources. ... Individuals in the mollusk species Donax variabilis show diverse coloration and patterning in their phenotypes. ... In medicine, a disorder is a functional abnormality or disturbance. ... A termite cathedral mound produced by a termite colony: a classic example of emergence in nature. ... A ciliopathy is a genetic disorder of the cellular cilia or the cilia anchoring structures, the basal bodies. ... cross-section of two cilia, showing 9+2 structure A cilium (plural cilia) is a fine projection from a eukaryotic cell that constantly beats in one direction. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is separately enclosed within its own lipid membrane. ... This article is about modern humans. ... Pleiotropy occurs when a single gene influences multiple phenotypic traits. ... Primary ciliary dyskinesia (PCD), also known as immotile ciliary syndrome, is a rare autosomal recessive genetic disorder caused by a defect in the action of the tiny hairs (cilia) lining the respiratory tract. ... The Bardet-Biedl syndrome is a a syndrome characterized mainly by obesity, pigmentary retinopathy, polydactyly, mental retardation, hypogonadism, and renal failure in fatal cases. ... Polycystic kidney disease (PKD) is a progressive, genetic disorder of the kidneys. ... The term Polycystic Liver Disease (PLD) is usually used to describe the presence of multiple cysts scattered throughout the normal liver tissue, in association with Polycystic kidney disease. ... Nephronophthisis is a genetic disorder of the kidneys which affects children. ... Alström syndrome is a rare genetic disorder. ... Meckel syndrome (also known as Meckel-Gruber Syndrome, Gruber Syndrome, Dysencephalia Splanchnocystica) is a rare and lethal genetic disorder, characterized by renal cystic dysplasia, central nervous system malformations, and hepatic developmental defects. ... Retinopathy is a general term that refers to some form of non-inflammatory damage to the retina of the eye. ...

Signs and symptoms

Signs and symptoms of Agenesis of the Corpus Callosum and other callosal disorders vary greatly among individuals. However, some characteristics common in individuals with callosal disorders include vision impairments, low muscle tone (hypotonia), poor motor coordination, delays in motor milestones such as sitting and walking, low perception of pain, delayed toilet training, chewing and swallowing difficulties, early speech and language delays, and social difficulties. Recent research suggests that specific social difficulties may be a result of impaired face processing.^[7] Unusual social behavior in childhood is often mistaken for or misdiagnosed as Asperger's syndrome or other autism spectrum disorders. Other characteristics sometimes associated with callosal disorders include seizures, spasticity, early feeding difficulties and/or gastric reflux, hearing impairments, abnormal head and facial features, and mental retardation.^[8] Hypotonia is a condition of abnormally low muscle tone (the amount of tension or resistance to movement in a muscle), often involving reduced muscle strength. ... Explain the dystonias connected with motor coordination. ... Face perception is the process by which the brain and mind understand and interpret the face, particularly the human face. ... Asperger described his patients as little professors. Aspergers syndrome (AS, or the more common shorthand Aspergers), is characterized as one of the five pervasive developmental disorders, and is commonly referred to as a form of high functioning autism. ... A boy with autism and his mother Autism refers to a spectrum of disorders, and lies somewhere under the umbrella of a greater encompassing spectrum, that of pervasive developmental disorders that involve the functioning of the brain. ... This article is about the medical condition. ... Spasticity is a disorder of the bodys motor system,and especially the Central Nervous Systems (CNS), in which certain muscles are continuously contracted. ...

Associated syndromes and conditions

Some syndromes that frequently include ACC are Aicardi syndrome, Andermann syndrome, Shapiro syndrome, Acrocallosal syndrome,septo-optic dysplasia, Mowat-Wilson syndrome and Menkes syndrome. Some conditions that are sometimes associated with ACC include maternal nutritional deficiencies or infections, metabolic disorders, Fetal alcohol syndrome, and orofacial abnormalities. ^[9] Aicardi syndrome is a congenital disorder thought to result from an abnormality of the X chromosome and characterized by absence of the corpus callosum, retinal abnormalities, and seizures (often infantile spasms). ... The Shapiro syndrome is a rare disorder consisting of paroxysmal hyperthermia (due to hypothalamic dysfunction of thermoregulation), epilepsy, and agenesis of the corpus callosum. ... Acrocallosal syndrome is a rare autosomal recessive syndrome characterized by corpus callosum agenesis, polydactyly, multiple dysmorphic features and many other symptoms. ... Septo-optic dysplasia (SOD) is a congenital malformation syndrome manifested by hypoplasia (underdevelopment) of the optic nerve, hypopituitarism, and absence of the septum pellucidum (a midline part of the brain). ... Mowat Wilson syndrome is a rare genetic disorder that was clinically delineated by Dr. D. R. Mowat and Dr. M. J. Wilson in 1998 (Journal of Medical Genetics, 1998, Vol 35, 617-623)[1]. The disorder is characterized by a number of health defects including Hirschsprungs disease, mental retardation... Menkes disease, also called the kinky hair disease or Menkes kinky hair syndrome, is a disease of abnormal copper metabolism. ... Fetal alcohol syndrome or FAS is a disorder of permanent birth defects that occurs in the offspring of women who drink alcohol during pregnancy. ...

Treatment

There are currently no specific medical treatments for callosal disorders, but individuals with ACC and other callosal disorders may benefit from a range of developmental therapies, educational support, and services. It is important to consult with a variety of medical, health, educational and social work professionals. Such professionals include neurologists, neuropsychologists, occupational therapists, physical therapists, speech-language pathologists, pediatricians, geneticists, special educators, early intervention specialists, and adult service providers. ^[10] A neurologist is a physician who is specialized in the diagnosis and treatment of neurologic diseases. ... // What is Occupational Therapy? Occupational therapy is skilled treatment that helps individuals achieve independence in all facets of their lives. ... Pediatrics (also spelled paediatrics or pædiatrics) is the branch of medicine that deals with the medical care of infants and children. ... Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ...

Prognosis

Prognosis varies depending on the type of callosal abnormality and associated conditions or syndromes. It is not possible for the corpus callosum to regenerate or degenerate (i.e., the corpus callosum will not regrow or diminish). ^[11]. Although some individuals with callosal disorders have average intelligence and lead normal lives, neuropsychological testing reveals subtle differences in higher cortical function compared to individuals of the same age and education without ACC.

Special cases

Kim Peek, inspiration for the film Rain Man, is famous for his savant abilities. Peek was born with agenesis of the corpus callosum, along with macrocephaly and damage to the cerebellum.^{[citation needed]} Kim Peek (born November 11, 1951), is a savant with a photographic or eidetic memory and developmental disabilities, possibly resulting from congenital brain abnormalities. ... Rain Man is a 1988 film which tells the story of a selfish yuppie who discovers that his father has left all of his estate to the autistic brother he never knew he had. ... An autistic savant (historically described as idiot savant) is a person with both autism and Savant Syndrome. ... Macrocephaly (from the greek words μακρύς, meaning long, and κεφάλη, meaning head), a type of cephalic disorder, is a condition in which the head circumference is larger than average for the age and sex of the infant or child. ...

Notes

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Common Era (or Anno Domini), in accordance with the Gregorian calendar. ... June 15 is the 166th day of the year (167th in leap years) in the Gregorian calendar. ...

External links

Support organisations:

• The ACC Network International network to provide information and a communication link for individuals with brain anomalies involving the corpus callosum, their families and the professionals who work with them.
• National Organization for Disorders of the Corpus Callosum Non - profit US organisation offering information and support.
• Corpal UK charity offering support to families caring for children with ACC.
• Agenesis of the Corpus Callosum Community A site with message boards for discussing ACC.
• ACC page from Contact a Family UK charity providing support and advice to families with disabled children or those with special needs.
• Aicardi Syndrome Foundation Support and information for families caring for children with Aicardi Syndrome.
• UCSF Fetal Treatment Center: Agenesis of the corpus callosum
• Caregiver Support and Personal Stories - Personal experiences of those affected by Agenesis of Corpus Callosum