Objective Riboflavin transporter deficiencies (RTDs), involving SLC52A3 and SLC52A2 genes, have recently been related to Brown-Vialetto-Van Laere (BVVL) syndrome, a hereditary paediatric condition associating motor neuropathy (MN) and deafness. BVVL/RTD has rarely been reported in adult patients, but is probably underdiagnosed due to poor knowledge and lack of awareness of this form of disease among neurologists. In this study, we aimed to investigate the phenotype and prognosis of RTD patients with late-onset MN.
Methods We retrospectively collected clinical, biological and electrophysiological data from all French RTD patients with MN onset after 10 years of age (n=6) and extracted data from 19 other similar RTD patients from the literature.
Results Adult RTD patients with MN had heterogeneous clinical presentations, potentially mimicking amyotrophic lateral sclerosis or distal hereditary motor neuropathy (56%), multinevritis with cranial nerve involvement (16%), Guillain-Barré syndrome (8%) and mixed motor and sensory neuronopathy syndromes (20%, only in SLC52A2 patients). Deafness was often diagnosed before MN (in 44%), but in some patients, onset began only with MN (16%). The pattern of weakness varied widely, and the classic pontobulbar palsy described in BVVL was not constant. Biochemical tests were often normal. The majority of patients improved under riboflavin supplementation (86%).
Interpretation Whereas late-onset RTD may mimic different acquired or genetic causes of motor neuropathies, it is a diagnosis not to be missed since high-dose riboflavin per oral supplementation is often highly efficient.
Statistics from Altmetric.com
Contributors CC and YN contributed equally in the conception of the manuscript, the acquisition of the data and drafting of a significant portion of the manuscript and the figure. CB contributed in drafting and editing a significant portion of the manuscript and the figure. GA, CC, AR, TL, JC, AV-M and CA contributed in drafting and editing a significant portion of the manuscript. All authors approved the final manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests YN received speech honoraria from Actelion and Orphan Europe, and received travel funding from Actelion, Shire and Genzyme.
Patient consent for publication Obtained.
Ethics approval This study was conducted in compliance with the French legislation and was authorised by the national committee for the protection of privacy and personal data (CNIL, no: 2211991). Patients were informed about the use of their deidentified data in this study.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. All data relevant to the study are included in the article or uploaded as supplementary information.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.