Childhood neurological presentation of a novel mitochondrial tRNA(Val) gene mutation.

We describe a young girl with a novel 1659T>C mutation in the tRNA(Val) gene of mitochondrial DNA (mtDNA) who presented with learning difficulties, hemiplegia, and a movement disorder, together with a raised cerebrospinal fluid (CSF) lactate. The mutation, which was present at high levels of heteroplasmy in patient tissues, interrupts a conserved Watson-Crick basepair in the TPsiC stem and has not previously been described in controls. This report further confirms the frequent association of mitochondrial tRNA mutation with neurological presentations, even in paediatric cases.