Autosomal dominant CMT6 has previously been found to harbour mutations in the Mitofusin 2 (MFN2) gene.9 X-linked recessive mutations have been identified in the phosphoribosylpyrophosphate synthetase I (PRPS1) gene in CMT6 families.10 Conversely, no genetic cause for the autosomal-recessive forms of CMT6 has been identified until the work described here, where we identify a novel mutation in the C12orf65 gene and then characterise this mitochondrial protein in CMT6. Here, PRPS1 is linked to hereditary motor and sensory neuropathy type 6.