[Human prion diseases: An overview]. / Enfermedades por priones humanas. Una revisión general.

Prion diseases are a group of neurodegenerative diseases. The disease-causing agent is a protein (PrP), that is normally produced in the nervous system, aggregated in an abnormal form. The abnormal protein, known as prion (PrPSc), is capable of self-propagation promoting the misfolding of the normal protein (PrP). These conditions can be acquired sporadically, genetically, or infectiously either by eating meat contaminated with prions or from iatrogenic exposure. The diagnosis of these diseases is often challenging. The use of highly sensitive and specific diagnostic tools, such as MRI and RT-QuIC, may aid in the diagnosis. Neuropathological examination of brain tissue ensures a definite diagnosis. At present, no treatment significantly improves the course of prion diseases; however, an early diagnosis is of paramount importance for patient care decision planning, infection control purposes, and genetic counseling.

Pharmacogenetics of siponimod: A systematic review.

Multiple sclerosis is a chronic inflammatory neurological disease, and siponimod (Mayzent) is the first oral treatment option for adult patients with secondary progressive multiple sclerosis. We performed a systematic review of the pharmacogenetics of Siponimod, and we found that (430 C>T; rs1799853) and CYP2C9 * 3 (1075 A>C; rs1057910), both translated no-function alleles, have been related to a lower metabolism of siponimod by CYP2C9 enzyme. The FDA-approved drug label and EMA risk management plan for siponimod require testing patients for CYP2C9 genotype before treatment starts. The FDA drug label states that siponimod is contraindicated in patients carrying a CYP2C9 * 3/* 3 genotype, and a daily maintenance dose of 1 mg in patients with CYP2C9 * 1/* 3 and * 2/* 3 genotypes. The EMA reported the potential long-term safety implications in CYP2C9 poor metabolizer patients treated with this drug. Based on this systematic review we concluded that CYP2C9 SNPs influence on siponimod response might be stated by assessing not only CYP2C9 * 2 and CYP2C9 * 3 but other genetic variants resulting in CYP2C9 IM/PM status. CYP2C9 IM phenotype translated from the CYP2C9 * 2 genotype should be revised since it is contradictory compared to other CYP2C9 no-function alleles, and CYP2C9 * 2 might be excluded from PGx testing recommendation before treatment starts with siponimod since it is not translated into a therapeutic recommendation.

Progressive Multifocal Leukoencephalopathy and Immune Reconstitution Inflammatory Syndrome after Discontinuation of Fingolimod.

Progressive multifocal leukoencephalopathy (PML) is a rare complication of immunosuppressive treatment in MS patients. Immune reconstitution inflammatory syndrome (IRIS) appears after the withdrawal of certain drugs such as natalizumab (NTZ) or fingolimod. The development of PML-IRIS after NTZ treatment has been described, and its diagnosis is made by clinical and radiological criteria and the determination of the John Cunningham virus in CSF. We present a clinical case of a patient with MS who, after the withdrawal of fingolimod, developed PML-IRIS despite sustained lymphopenia. This is important for pharmacovigilance purposes, not only for NTZ but also for alternative drugs used in MS treatment.

Clinical and Laboratory Features in Anti-NF155 Autoimmune Nodopathy.

BACKGROUND AND OBJECTIVES: To study the clinical and laboratory features of antineurofascin-155 (NF155)-positive autoimmune nodopathy (AN). METHODS: Patients with anti-NF155 antibodies detected on routine immunologic testing were included. Clinical characteristics, treatment response, and functional scales (modified Rankin Scale [mRS] and Inflammatory Rasch-built Overall Disability Scale [I-RODS]) were retrospectively collected at baseline and at the follow-up. Autoantibody and neurofilament light (NfL) chain levels were analyzed at baseline and at the follow-up. RESULTS: Forty NF155+ patients with AN were included. Mean age at onset was 42.4 years. Patients presented with a progressive (75%), sensory motor (87.5%), and symmetric distal-predominant weakness in upper (97.2%) and lower extremities (94.5%), with tremor and ataxia (75%). Patients received a median of 3 (2-4) different treatments in 46 months of median follow-up. Response to IV immunoglobulin (86.8%) or steroids (72.2%) was poor in most patients, whereas 77.3% responded to rituximab. HLA-DRB1*15 was detected in 91.3% of patients. IgG4 anti-NF155 antibodies were predominant in all patients; anti-NF155 titers correlated with mRS within the same patient (r = 0.41, p = 0.004). Serum NfL (sNfL) levels were higher in anti-NF155+ AN than in healthy controls (36.47 vs 7.56 pg/mL, p < 0.001) and correlated with anti-NF155 titers (r = 0.43, p = 0.001), with I-RODS at baseline (r = -0.88, p < 0.001) and with maximum I-RODS achieved (r = -0.58, p = 0.01). Anti-NF155 titers and sNfL levels decreased in all rituximab-treated patients. DISCUSSION: Anti-NF155 AN presents a distinct clinical profile and good response to rituximab. Autoantibody titers and sNfL are useful to monitor disease status in these patients. The use of untagged-NF155 plasmids minimizes the detection of false anti-NF155+ cases. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that anti-NF155 antibodies associate with a specific phenotype and response to rituximab.