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Familial hemiplegic migraine (FHM)
Familial hemiplegic migraine (FHM) is an autosomal dominantly inherited disorder characterised by migraine attacks associated with temporary unilateral hemiparesis or hemiplegia, at times accompanied by ipsilateral numbness or tinglin with or without a speech disturbance. Other migraine symptoms may be present or not. Patients may also experience disturbance of consciousness, and rarely coma. The neurological deficit is transient and usually clears in minutes to hours, or resolves with the beginning of the headache phase.
This disease has been associated with missense mutations in the CACNA1A gene gene. Cases involving the CACNA1A gene have been found in approximately 50% of FHM cases. Mutations in this gene are also associated with episodic ataxia type 2 (EA-2) and spinocerebellar ataxia type 6 (SCA6).
Test: DNA extraction, PCR, DNA sequencing of the entire CACNA1A encoding sequence (49 exons).
