Corpus callosum agenesis is a rare disorder that occurs at birth (congenital). It is characterized by partial or total absence (agenesis) of the brain area connecting the two cerebral hemispheres. This part of the brain usually consists of transverse fibers. The cause of agenesis of corpus callosum is usually not known but may be inherited as an autosomal recessive trait.
It may also be due to infection or injury during the twelfth to the twenty-second week of pregnancy (intrauterine) leading to developmental disorders of the fetal brain. Intrauterine exposure to alcohol (fetal alcohol syndrome) may also result in ACC. In some cases, mental retardation can occur, but intelligence can only be slightly impaired and subtle psychosocial symptoms can occur.
ACC is often diagnosed during the first two years of life. An epileptic seizure may be the first symptom indicating that the child should be examined for brain dysfunction. The disorder can be asymptomatic in the mildest cases for many years.
Symptoms of corpus callosum agenesis
Corpus callosum agenesis may initially become apparent as a result of epileptic seizures in the first weeks of life or during the first two years. However, not all people with ACC have epileptic seizures. (For more information on this type of seizure, select “epilepsy” as the search term in the rare disease database).
Other symptoms that may occur early in life are feeding problems and delays in keeping the head upright. Sitting, standing and walking can also be delayed. Impaired mental and physical development and/or accumulation of fluid in the skull. (hydrocephalus) are also a symptom of the early type of this disorder. (For more information, select “hydrocephalus” as the search term in the Rare Disease database).
Progressive mental retardation, impaired hand-eye coordination, and visual or auditory (auditory) memory impairment can be diagnosed by neurological testing of ACC patients.
In some mild cases, symptoms may not appear for many years. Older patients are usually diagnosed during symptoms tests such as convulsions, monotonous or repetitive speech or headaches. In mild cases, it can be overlooked due to the lack of obvious symptoms in childhood.
Some patients may have deep-set eyes and the prominent forehead. An abnormally small head (microcephaly) or sometimes an unusually large head (macrocephaly) may be present. Skin markers in front of the ears (pre-human skin markers), one or more bent fingers. (Camptodactyly) and delayed growth was also associated with some cases of corpus callosum agenesis.
In other cases, widely spaced eyes (telecanthus), small nose with inverted nostrils, abnormally shaped ears, an excessive skin of the neck, short hands, weak muscle tone (hypotension), larynx irregularities, heart defects, and symptoms The Pierre-Robin syndrome may be present. (For more information, select “Pierre-Robin” as the search term in the Rare Diseases database).
The Aicardi syndrome, considered to be inherited as a dominant disorder associated with the X chromosome, consists of agenesis of the corpus callosum, infectious contractions, and an abnormal eye structure. This disorder is an extremely rare congenital disorder in which frequent epileptic seizures, striking anomalies of the middle ocular mantle (choroid) and retinal layers, and lack of structure connecting the two cerebral hemispheres (the corpus callosum) accompany severe mental retardation. The problem concerns only women. (For more information about this disorder, select “Aicardi” as the search term in the Rare Disease Database.)
Other of symptoms corpus callosum agenesis
Andermann’s syndrome, identified in 1972, is a genetic disease characterized by a combination of agenesis of the corpus callosum, mental retardation and progressive disturbances of the nervous-sensory system (neuropathy). All known cases of this disorder come from the Charlevoix District and Saguenay-Lac St. Jean in Quebec, Canada. The gene responsible for this rare form of ACC has been recently identified, and this gene (SLC12A6) is currently available.
XLAG (combined with lissencephaly with ambiguous genitalia is a rare genetic disorder in which males have small and smooth brains (lissencephaly), small penis, severe mental retardation and difficult to control epilepsy, which is caused by mutations in the ARX gene. Mutations can cause the same ACC whereas less serious mutations in men can cause mental retardation. Testing this disorder is also clinically available.