Whole-exome sequencing reveals a missense mutation in the KCND3 gene in a patient with SCA19/22

Abstract

We report a 45-year-old Japanese man with SCA19/22. Whole-exome sequencing revealed a heterozygous missense mutation (c.1169G>A, p.S390N) in the KCND3 gene. Although this mutation has been reported to cause SCA19 in a Dutch patient, a co-segregation study of the mutation has not been carried out. In the present family, since the S390M mutation was found in the patient but not in the unaffected siblings, we suspected co-segregation of this mutation with the disease in our family. Our patient presented with juvenile-onset pure cerebellar ataxia associated with pes cavus, which has not been previously described in SCA19/22. Thus, our patient would expand the clinical spectrum of SCA19/22. In the case of juvenile-onset pure cerebellar ataxia with autosomal dominant transmission, SCA19/22 should be considered.