Familial idiopathic basal ganglia calcification (FIBGC) is a condition characterized by abnormal deposits of calcium (calcification) in the brain. These calcium deposits typically occur in the basal ganglia, which are structures deep within the brain that help start and control movement; however, other brain regions can also be affected.
The signs and symptoms of FIBGC include movement disorders and psychiatric or behavioral problems. These abnormalities usually appear in a person's thirties, but they can appear anytime during adulthood. The movement problems experienced by people with FIBGC include involuntary tensing of various muscles (dystonia), difficulty coordinating movements (ataxia), and uncontrollable movements of the limbs (choreoathetosis). Affected individuals often have seizures as well. The psychiatric and behavioral problems include difficulty concentrating, memory loss, changes in personality, a distorted view of reality (psychosis), and decline in intellectual function (dementia). An estimated 20 to 30 percent of people with FIBGC have one of these psychiatric disorders.
How common is FIBGC?
FIBGC is thought to be a rare disorder; about 30 affected families have been described in the medical literature. However, because brain imaging tests are needed to recognize the calcium deposits, this condition is believed to be under-diagnosed.
What genes are related to FIBGC?
Researchers have not identified any specific genes related to FIBGC. Although the causes of this disorder are unknown, FIBGC appears to be associated with changes in chromosomes 2, 7, 8, 9, and 14 in some families, suggesting that multiple genes are involved in this condition.
Researchers suggest that the calcium deposits characteristic of FIBGC impair normal functioning in different parts of the brain. Calcium deposits may disrupt the pathways that connect the basal ganglia to other areas of the brain, particularly the frontal lobes. These areas at the front of the brain are involved in reasoning, planning, judgment, and problem-solving. The regions of the brain that regulate social behavior, mood, and motivation may also be affected. Disrupted signals between various parts of the brain may be responsible for the signs and symptoms of FIBGC.
It is unclear whether the calcification of the basal ganglia and other brain regions causes the movement and behavioral problems in people with FIBGC. Research has shown that people with significant calcification tend to have more signs and symptoms of FIBGC than people with little or no calcification. However, this association does not apply to all people with FIBGC. Researchers are working to determine what causes the calcium deposits to form and how they are related to the movement and behavioral problems in people with FIBGC.
How do people inherit FIBGC?
This condition is inherited in an autosomal dominant pattern. Autosomal dominant inheritance means one copy of an altered gene in each cell is sufficient to cause the disorder, although no specific gene changes have been associated with FIBGC. In most cases, an affected person has one parent with the condition.
Where can I find information about diagnosis, management, or treatment of FIBGC?
These resources address the diagnosis or management of FIBGC and may include treatment providers.
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