SLC52A2 and Respiratory insufficiency: As three patients with mutations in SLC52A2 were identified from an undiagnosed cohort of 63 patients with cranial neuropathies and sensorimotor neuropathy ± respiratory insufficiency which was Sanger sequenced for SLC52A1, SLC52A2 and SLC52A3, and none of the patients in this cohort were found to harbour mutations in SLC52A1 or SLC52A3, it seems that SLC52A2 is perhaps the most common cause of Brown-Vialetto-Van Laere syndrome.