Mutation information:
NumberExon/IntronNucleotide change Protein changeLocation Mutation typeConsequencesPhenotype InheritanceReference
2536c.787C>Gp.Leu263ValDIS5MissenseN→N (32); GOF FHM+EP2Familial,P=5/5Barros J.2014
Familial(Paternal, FHM+EP),P=5/5Castro MJ.2009
HM + EpNAKahlig KM.2008

Functional information:
NumberNucleotide changeProtein changeLocationPhenotypeFunctional defect type Details of the major biophysical abnormalities.Reference
6c.787C>Gp.Leu263Val(L263V)DIS5FHM+EPGOF Exhibited gain-of function features, including delayed entry into, as well as accelerated recovery from, fast inactivation; depolarizing shifts in the steady-state voltage dependence of fast and slow inactivation; increased persistent current; and delayed entry into slow inactivation.Kahlig KM.2008

Inheritance information:
NumberNucleotide changeProtein changeMutation type Proband's phenotype1st transmitter's phenotype Mosaic Affected generationsPenetranceReference
30c.787C>Gp.Leu263Val(DIS5)MissenseFHM+EPNA 25/5Barros J.2014
FHM+EPFHM+EP(Paternal) 25/5Castro MJ.2008

[c.787C>G] Clinical description

The Portuguese FHM family spans three generations. Six patients suffered from typical hemiplegic migraine attacks, with an age of onset varying from 10 to 18 years and an attack frequency of less than one to three per year. None of the patients reported (inter)ictal cerebellar abnormalities. Generalized tonic-clonic seizures (and in one case additional complex partial seizures) were co-segregating with hemiplegic migraine in three family members (i.e. II:2, II:5 and III:4), and probably in one deceased person (I:1) [seizures similar to those of the other family members were reported by his wife (I:2)]. Onset of seizures was between 4 and 8 years. Interictal EEG recording was unremarkable in patients II:2, II:5 and III:4. Structural lesions in these patients were excluded on the basis of computed tomography (i.e. II:2 and II:5) or magnetic resonance imaging (i.e. III:4) investigations (data not shown). Febrile convulsions were not reported in any of the family members. Epileptic seizures occurred independently from FHM attacks, and the age at onset was generally somewhat later than for the FHM attacks. Treatment with a low daily dose (400 mg/day) of carbamazepine in patients II:2 and II:5, who had a body weight of < 60 kg, was successful with respect to both epileptic and hemiplegic attacks as patients remained attack free. Patient III:4 occasionally had epileptic attacks when treated with a daily dose of 600 mg of carbamazepine, but he did not tolerate a higher dose. Psychomotor development of all individuals was normal(Castro MJ, et al. Cephalalgia. 2009 Mar; 29(3):308-13. [19220312]).