Fahr's Disease, also known as Fahr's syndrome or Familial Cerebrovascular Ferrocalcinosis, is a rare hereditary neurodegenerative disorder characterized by bilateral calcification of the basal ganglia and other brain regions. First described by Karl Theodor Fahr in 1930, this condition is classified among the Neurodegeneration with Brain Iron Accumulation (NBIA) disorders.
- Full Name: Fahr's Disease / Idiopathic Familial Cerebral Ferrocalcinosis
- Synonyms: Fahr's syndrome, Striopallidodentate calcinosis, Cerebrotendinous calcification
- Classification: Neurodegeneration with Brain Iron Accumulation (NBIA) / Movement Disorder / Neurogenetic Disorder
- ICD-10 Code: G23.8 (Other degenerative diseases of basal ganglia)
- Prevalence: Approximately 1 in 1,000,000 individuals
- Inheritance: Autosomal dominant (most cases); sporadic cases also reported
- Age of Onset: Highly variable (2nd to 7th decade), typically in middle age
- Gender Distribution: Slight male predominance reported in some studies
Fahr's disease follows an autosomal dominant inheritance pattern with high penetrance. Multiple family generations may be affected.
Mutations in the following genes are associated with Fahr's disease:
-
SLC20A2 (Phosphate transporter 2)
- Most common causative gene
- Encodes PiT2, a phosphate transporter
- Accounts for approximately 40% of familial cases
-
PDGFRB (Platelet-Derived Growth Factor Receptor Beta)
- Second most common gene
- Encodes a receptor tyrosine kinase
-
PLCB4 (Phospholipase C Beta 4)
-
JAM2 (Junctional Adhesion Molecule 2)
- SLC20A2 mutations: Impair phosphate transport, leading to abnormal calcium/iron deposition
- PDGFRB mutations: Affect vascular integrity and mineral metabolism
- PLCB4 mutations: Disrupt cellular signaling pathways
- Parkinsonism: Bradykinesia, rigidity, tremor
- Dystonia: Involuntary muscle contractions
- Chorea: Involuntary jerky movements
- Ataxia: Coordination difficulties
- Progressive dementia
- Executive function deficits
- Memory impairment
- Behavioral changes
- Depression
- Anxiety
- Personality changes
- Psychosis (rare)
- Seizures: May occur in some patients
- Headache: Chronic or recurrent
- Speech difficulties: Dysarthria
- Swallowing difficulties: Dysphagia
The hallmark finding is bilateral, symmetric calcifications:
- Basal ganglia (globus pallidus, putamen, caudate)
- Dentate nucleus of cerebellum
- Thalamus
- Subcortical white matter
- T2 hyperintensities in affected regions
- May show iron deposition on susceptibility-weighted imaging
- Progressive brain atrophy in advanced cases
- Neuroimaging: Bilateral calcification of basal ganglia on CT
- Clinical presentation: Movement disorder + cognitive decline
- Exclusion: Exclusion of other causes (infectious, metabolic, toxic)
- SLC20A2 sequencing
- PDGFRB sequencing
- PLCB4 sequencing
- JAM2 sequencing
The primary abnormality involves disrupted phosphate and mineral homeostasis:
- Impaired phosphate transport (SLC20A2 mutations)
- Abnormal cellular mineral metabolism
- Progressive calcium and iron deposition
- Neurotoxicity from mineral accumulation
- Iron deposition leads to oxidative stress
- Mitochondrial dysfunction
- Neuronal loss in affected regions
- Progressive cerebral atrophy
- Levodopa: May provide benefit for parkinsonism
- Anticholinergics: For dystonia
- Botulinum toxin: For focal dystonia
- Benzodiazepines: For chorea
- Iron chelation therapy: Deferoxamine trials
- Phosphate binders: Sevelamer
- Gene therapy: Under investigation
- Course: Progressive, but variable rate
- Life expectancy: Often normal with appropriate management
- Disability: Variable, from mild to severe impairment
- Treatment response: Often partial and temporary