Information on the following diseases can be found in the Related Disorders section of this report:

• Parkinson Disease

Fahr's Disease is marked by abnormal calcium deposits in areas of the brain, notably the basal ganglia, cerebral cortex, dentate nucleus, subthalamus and red nucleus areas. Loss of brain cells also occurs. These mineral deposits may also be found in areas where the myelin sheath surrounding nerves has been lost (demyelination), and in fatty (lipid) deposits. The heads of people with Fahr's Disease are often smaller than normal and appear to be round.

Progressive deterioration of mental abilities (dementia) and loss of previous motor development are accompanied by spastic paralysis and in some cases, twisting movements of the hands and feet (athetosis). Vision disturbances (optic atrophy) and ear infections may also occur. Features of Parkinson's Disease found in this disorder may include tremors and rigidity, a masklike facial expression, shuffling walk, and a pill rolling motion of the fingers. Muscle cramping (dystonia), uncontrollable spasmodic irregular movements (chorea), and seizures can also occur. (For more information on Parkinson's Disease, please choose "Parkinson" as your search term in the Rare Disease Database.)

The parathyroid glands may malfunction and low blood levels of calcium (hypoparathyroidism) may also occur in some cases of Fahr's Disease.

Fahr’s Disease is often familial. In many individuals with the disorder, Fahr’s Disease is thought to be inherited as an autosomal recessive trait. In other affected families (kindreds), the condition appears to be transmitted as an autosomal dominant trait. Human traits, including the classic genetic diseases, are the product of the interaction of two genes for that condition, one received from the father and one from the mother.

In recessive disorders, the condition does not appear unless a person inherits the same defective gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease but usually will not show symptoms. The risk of transmitting the disease to the children of a couple, both of whom are carriers for a recessive disorder, is 25 percent. Fifty percent of their children risk being carriers of the disease but generally will not show symptoms of the disorder. Twenty-five percent of their children may receive both normal genes, one from each parent, and will be genetically normal (for that particular trait). The risk is the same for each pregnancy.

In dominant disorders, a single copy of the disease gene (received from either the mother or father) will be expressed "dominating" the other normal gene and resulting in the appearance of the disease. The risk of transmitting the disorder from affected parent to offspring is 50 percent for each pregnancy regardless of the sex of the resulting child. The risk is the same for each pregnancy.

In other individuals with Fahr’s Disease, the condition may appear to occur randomly for unknown reasons (sporadically). According to reports in the medical literature, it is possible that certain sporadic cases (and, perhaps, even some familial cases) may result from an unidentified infection during fetal development (intrauterine infection).

As discussed above, Fahr’s Disease is characterized by the presence of abnormal calcium deposits (calcification) in the basal ganglia and other regions of the brain. (The basal ganglia consists of nerve cell clusters deep in the brain that assist in initiating and regulating movements.) Because there is no apparent explanation for such calcification (idiopathic), the disorder is sometimes referred to as idiopathic basal ganglia calcification (IBGC).

Idiopathic calcification of the basal ganglia and other regions of the brain is a finding that may also be associated with numerous infectious diseases, inborn errors of metabolism, movement disorders, or genetic syndromes. In many cases, such calcification may appear as an incidental finding (as seen upon specialized x-ray imaging studies [e.g., CT scanning]) with no apparent associated symptoms or clear underlying cause. However, as discussed earlier, in some families and apparently sporadic cases, the calcification may lead to specific symptoms, including certain abnormalities of movement.

In one multigenerational family with autosomal dominant IBGC (Fahr’s Disease), each generation appeared to develop symptoms at an earlier age than those in previous generations, a finding known as "genetic anticipation." In addition, during genetic analysis of this kindred, a gene responsible for the disorder (designated as IBGC1) was mapped to a specific location (genetic locus) on the long arm (q) of chromosome 14 (14q). Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as "p" and a long arm identified by the letter "q." Chromosomes are further subdivided into bands that are numbered.

Further research is necessary to help locate, identify, and characterize the nature of the specific disease gene(s) that may play a role in causing Fahr’s Disease.

Fahr’s Disease is a rare disorder that appears to affect males and females in equal numbers. Reports of the disorder in the medical literature include sporadic cases as well as affected individuals in several multigenerational families. In kindreds with dominantly inherited IBGC or Fahr’s Disease, symptoms typically become apparent from approximately age 30 to 60. According to some reports, in individuals with autosomal recessive Fahr’s Disease, symptom onset may occur as early as infancy, during adolescence, or by early adulthood.

The following disorder may be associated with Fahr's Disease as a secondary characteristic. It may not be necessary for a differential diagnosis:

Parkinson's Disease is a progressive neurological disorder characterized by tremor, muscular rigidity, slowness of movements (bradykinesia) balance problems and difficulty in initiating movements. In Parkinson Disease, there are degenerative changes in the substantia nigra and other pigmented regions of the brain, and a decrease in dopamine levels in neurons associated with these areas. In the great majority of cases, the cause is unknown. Parkinsonian symptoms may very rarely appear after infarcts (strokes), tumors in the vicinity of the basal ganglia, hydrocephalus, cerebral trauma, encephalitis, or exposure to certain drugs and toxins. Parkinson's Disease appears in adulthood and progresses very slowly over years. (For more information on this disorder, choose "Parkinson" as your search term in the Rare Disease Database.)

Treatment of ear infections in Fahr's Disease involves antibiotic drugs and/or pain medication as needed. Lithium Carbonate may be prescribed to treat some psychotic symptoms of this disorder. Other treatment is symptomatic and supportive. Genetic counseling may be of benefit for patients and their families if they have the hereditary form of Fahr's Disease.

Research is being conducted on Fahr's Disease to find better diagnostic techniques and enhance understanding of genetic aspects. A Fahr's Disease registry has been developed and families are invited to register cases of Fahr's Disease with:

Bala V. Manyam, M.D.
Fahr's Disease Registry
Parkinson's Disease and Movement Disorders Clinic
Southern Illinois University School of Medicine
P.O. Box 19230
Springfield, IL 62794-9230

Online Mendelian Inheritance in Man, OMIM (TM). John Hopkins University, Baltimore, MD. MIM Number 213600; 9/30/99. Available at: http://www.ncbi.nlm.nih.gov/htbin-post/Omim/dispmim?213600.

The inherited metabolic diseases of the nervous system. In: Adams RD, et al., eds. Principles of Neurology. 6th ed. New York, NY; McGraw-Hill Companies, Inc.; 1997:974.

Munir KM. The treatment of psychotic symptoms in Fahr's disease with lithium carbonate. J Clin Psychopharmacol. 1986;6:36-38.

Kobayashi S, et al. Idiopathic nonarteriosclerotic cerebral calcification (Fahr's disease): an electron microscopic study. Acta Neuropathol. 1987;73:62-66.

Geschwind DH, et al. Identification of a locus on chromosome 14q for idiopathic basal ganglia calcification (Fahr disease). Am J Hum Genet. 1999;65:764-772.