CACNA1A-p.Thr501Met mutation associated with familial hemiplegic migraine: a family report.

Background And Aims: Hemiplegic migraine (HM) is a rare form of migraine characterized by the presence of a motor and other types of aura. HM can be sporadic or familial. Familial hemiplegic migraine (FHM) is an autosomal dominant disorder, classified into 3 subtypes, based on the gene involved (CACNA1A in FHM1, ATP1A2 in FHM2 and SCN1A in FHM3). The clinical presentation is highly heterogeneous and some attacks may be severe. We report the clinical characteristics and genetic analysis of 12 patients belonging to a family with CACNA1A-p.Thr501Met gene mutation.

Methods: We screened for mutations in CACNA1A gene 15 patients belonging to the same family. The exonic sequences of CACNA1A were analyzed using a Tru-seq® Custom Amplicon (TSCA) (Illumina Inc., San Diego, CA) targeted capture and paired end library kit. Sanger sequencing was used to confirm CACNA1A variants and segregation analysis.

Results: CACNA1A-p.Thr501Met mutation was found in 12 of the 15 patients screened, which was compatible with the diagnosis of FHM1. Attacks of hemiplegic migraine were reported by 10 of the 12 subjects (83.33%). Only one subject developed persistent mild cerebellar symptoms and none of the subjects developed cerebellar atrophy.

Discussion: The variant p.Thr501Met was described previously in association with episodic ataxia and rarely with FHM related to cerebellar symptoms. FHM1 has a broad clinical spectrum and about half of the families have cerebellar involvement. In our study, only one patient developed persistent cerebellar deficits. These data suggest that CACNA1A-p.Thr501Met mutation can occur prevalently as hemiplegic migraine.