Familial Hemiplegic Migraine
Familial hemiplegic migraine (FHM) is an inherited form of hemiplegic migraine. Hemiplegic migraine is a type of migraine with aura that causes motor impairment (such as weakness) in addition to at least one visual, sensory, or speech disturbance (aura) that occurs before the migraine headache begins. FHM commonly begins during childhood or adolescence. The symptoms of FHM can be scary and distressing.
FHM is currently classified into 4 subtypes, distinguished by their genetic cause:
FHM is currently classified into 4 subtypes, distinguished by their genetic cause:
- FHM type 1 (the most common type) is caused by mutations in the CACNA1A gene and is commonly associated with cerebellar degeneration.
- FHM type 2 is caused by mutations in the ATP1A2 gene and may be associated with seizures.
- FHM type 3 is caused by mutations in the SCN1A gene.
- FHM type 4 is diagnosed if no mutation currently known to cause FHM can be identified.