DNAJC3 and diabetes mellitus: Bi-allelic loss-of-function mutations in DNAJC3, encoding a co-chaperone of BiP, one of the major chaperones of the ER, have been shown to cause neurodegeneration with early-onset ataxia, upper-motor-neuron signs, demyelinating neuropathy, and cerebral atrophy associated with diabetes mellitus (Synofzik et al., 2014).