Tardive Reactivation of Progressive Multiple Sclerosis During Treatment with Biotin.

Multiple sclerosis (MS) is a common autoimmune disease of the central nervous system, causing neurological disability in young adults. A growing understanding of its immunopathogenesis has led to an expanding array of therapies. Notable new advances in disease-modifying therapies for relapsing forms of multiple sclerosis that are based on anti-inflammatory activity have recently been developed. Management of progressive MS is still challenging. Data published in 2014 suggested that daily high doses of biotin, a vitamin involved in myelin synthesis, might have a beneficial impact on disability and progression in progressive MS. However, some patients worsened while on biotin without any clear explanation for this effect. We report the case of a 41-year-old patient suffering from primary progressive (PP) MS who presented after 16 months of treatment with high doses of biotin (QIZENDAY) with worsening of his Expanding Disability Status Scale (EDSS) score and the appearance of a symptomatic new T2 pseudo-tumoural lesion on brain magnetic resonance imaging (MRI), suggestive of tardive inflammatory reactivation possibly due to the biotin. The newer and more effective therapies for MS are, however, associated with risks that necessitate an active management strategy and continuous vigilance. Physicians should be aware of iatrogenic neurological complications and the possible paradoxical effects of biotin. Future treatment approaches to progressive MS must include identification of a biomarker of disease activity. The study of neurofilaments in the cerebrospinal fluid (CSF) and the serum could be of interest when determining the optimal treatment strategy.

Mutation of the PDGFRB gene as a cause of idiopathic basal ganglia calcification.

OBJECTIVES: To identify a new idiopathic basal ganglia calcification (IBGC)-causing gene. METHODS: In a 3-generation family with no SLC20A2 mutation, we performed whole exome sequencing in 2 affected first cousins, once removed. Nonsynonymous coding variants, splice acceptor and donor site variants, and frameshift coding indels (NS/SS/I) were filtered against dbSNP131, the HapMap Project, 1000 Genomes Project, and our in-house database including 72 exomes. RESULTS: Seventeen genes were affected by identical unknown NS/SS/I variations in the 2 patients. After screening the relatives, the p.Leu658Pro substitution within the PDGFRB gene remained the sole unknown mutation segregating with the disease in the family. This variation, which is predicted to be highly damaging, was present in 13 of 13 affected subjects and absent in 8 relatives without calcifications. Sequencing PDGFRB of 19 other unrelated IBGC cases allowed us to detect another potentially pathogenic substitution within PDGFRB, p.Arg987Trp, also predicted to be highly damaging. PDGFRB encodes a protein involved in angiogenesis and in the regulation of inorganic phosphate (Pi) transport in vascular smooth muscle cells via Pit-1, a Pi transporter encoded by SLC20A1. CONCLUSION: Mutations of PDGFRB further support the involvement of this biological pathway in IBGC pathophysiology.

Lewis-Sumner syndrome and Tangier disease.

OBJECTIVE: To report unusual electrophysiologic data in a patient with Tangier disease in an effort to better understand the pathophysiologic features of the peripheral nerve lesions in this disease. DESIGN: Case report. PATIENT: A 15-year-old girl had subacute onset of asymmetric neuropathy with persistent conduction block, resembling Lewis-Sumner syndrome. MAIN OUTCOME MEASURES: Electrophysiologic data in Tangier disease. RESULTS: After initially unsuccessful treatment with intravenously administered immunoglobulins, the finding of an abnormal lipid profile led to the diagnosis of Tangier disease due to the R587W mutation in the adenotriphosphate-binding cassette transporter-1 gene (ABCA1) (OMIM 9q22-q31). CONCLUSIONS: Conduction block, which is the electrophysiologic hallmark of focal demyelination, can be present in Tangier disease. It could be induced by focal nerve ischemia or by preferential lipid deposition in the paranodal regions of myelinated Schwann cells. The presence of a conduction block in Tangier disease may lead to a misdiagnosis of dysimmune neuropathy.