What is the genetic cause of familial hemiplegic migraine (FHM) type 1?

Updated: Oct 21, 2019
  • Author: Jasvinder Chawla, MD, MBA; Chief Editor: Helmi L Lutsep, MD  more...
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FHM type 1 is characterized clinically by episodes that commonly include nystagmus and cerebellar signs. This disorder is caused by mutations in the CACNA1A gene located on 19p13, which codes for a brain-specific calcium channel. Mutations in CACNA1A were previously thought to account for 50% of cases of FHM, [34] but a Danish study showed that only 7% of patients with a clinical diagnosis of FHM had a mutation in that gene. [35]

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