Identification of a Novel Homozygous SPG7 Mutation in a Japanese Patient with Spastic Ataxia: Making an Efficient Diagnosis Using Exome Sequencing for Autosomal Recessive Cerebellar Ataxia and Spastic Paraplegia

Autosomal recessive cerebellar ataxias and autosomal recessive hereditary spastic paraplegias are clinically and genetically heterogeneous disorders with diverse neurological and non-neurological features. We herein describe a Japanese patient with a slowly progressive form of ataxia and spastic paraplegia. Using whole exome sequencing, we identified a novel homozygous frameshift mutation in SPG7, encoding paraplegin, in this patient. This is the first report of an SPG7 mutation in the Japanese population. For disorders previously undetected in a particular population, or unrecognized/atypical phenotypes, exome sequencing may facilitate molecular diagnosis.