The abovementioned symptoms, especially in combination with a positive family anamnesis.
Familial hemiplegic Migraine Type 3, FHM3 - SCN1A
Clinical Features
According to diagnostic criteria, Familiar Hemiplegic Migraine (FHM) is a migraine with aura in conjunction with a positive family anamnesis (at least one first-degree relative with similar attacks), whereby the aura characteristically includes hemiparess of varying degrees. These pareses can be prolonged, even beyond the duration of the headache. Other focal neurological symptoms such as impaired vision (scintillating scotoma, hemianopsia), sensory disturbance (wandering paresthesia / hypesthesia), or speech disorders may occur in conjunction with aura. Vigilance problems (from light confusion to coma) or rare psychiatric abnormalities have also been described. Magnetic resonance imaging may also reveal cerebellar abnormalities (vermis atrophy in some FHM1 families). Recurrent migraine attacks may begin in a patient’s childhood or teenage years. The severity of the symptoms can vary greatly in affected families.
FHM3 is caused by mutations in the SCN1A gene; mutations in this gene also cause various forms of epilepsy.
Genetic Information
The SCN1A gene is located on chromosome (2q24) and codes for a sodium channel protein type 1, subunit alpha. SCN1A mutations follow an autosomal dominant pattern of inheritance with incomplete penetrance. New mutations are possible.
Prevalence
Rare
Diagnostic
Indication
Method
All exons as well as their flanking regions are analyzed using DNA sequencing.
Deletions and/or duplications of one or more exons are captured using MLPA.
Sample Requirement
2 - 4 ml of EDTA blood
Duration
4 - 6 weeks