[P2-172] Acquired progressive cerebellar atrophy in two cases with CACNA1A gene mutation
[Introduction] Mutations in CACNA1A gene, which encodes P/Q-type voltage-gated calcium channel Cav2.1, cause familial hemiplegic migraine, episodic ataxia type 2, and spinocerebellar ataxia type 6. Although cerebellar atrophy (CA) had been reported previously in patients with CACNA1A mutation, there is no report about cerebellar change while initially it was normal. We report two cases with CA, which was not observed on first MRI. [Case description] First case, a 11-year-old boy, was not able to sit alone at the age of 9 months. Brain MRI at the age of 18 months was normal. At the age of 3 years, his developmental quotient (DQ) was 46. He was referred with seizure and ataxia. MRI revealed CA, which was progressing at the age of 11 years. Second case, a 5-year-old boy, was referred with low DQ (below 50) at the age of 15 months. Brain MRI was normal. At the age of 32 months, he showed ataxia with CA on MRI. At the age of 4 years, he presented with transient ataxia. Electroencephalogram revealed no epileptic discharge. Acetazolamide prevent from recurrent ataxia. MR spectroscopy revealed quantitatively low N-acetylaspartate at the cerebellum in both cases. Whole-exome sequencing identified a novel mutation (p.S1799L) and a known mutation (p.F1506S) in CACNA1A gene in each case. [Conclusions] It has been reported that the phenotype with CACNA1A mutations is variable and thus CA may be observed in not all cases. CA can be acquired. We recommend to perform follow-up MRI for the patients with CACNA1A mutation.