Genetic Dystonias: Update on Classification and New Genetic Discoveries.

PURPOSE OF REVIEW: Since the advent of next-generation sequencing, the number of genes associated with dystonia has been growing exponentially. We provide here a comprehensive review of the latest genetic discoveries in the field of dystonia and discuss how the growing knowledge of biology underlying monogenic dystonias may influence and challenge current classification systems. RECENT FINDINGS: Pathogenic variants in genes without previously confirmed roles in human disease have been identified in subjects affected by isolated or combined dystonia (KMT2B, VPS16, HPCA, KCTD17, DNAJC12, SLC18A2) and complex dystonia (SQSTM1, IRF2BPL, YY1, VPS41). Importantly, the classical distinction between isolated and combined dystonias has become harder to sustain since many genes have been shown to determine multiple dystonic presentations (e.g., ANO3, GNAL, ADCY5, and ATP1A3). In addition, a growing number of genes initially linked to other neurological phenotypes, such as developmental delay, epilepsy, or ataxia, are now recognized to cause prominent dystonia, occasionally in an isolated fashion (e.g., GNAO1, GNB1, SCN8A, RHOBTB2, and COQ8A). Finally, emerging analyses suggest biological convergence of genes linked to different dystonic phenotypes. While our knowledge on the genetic basis of monogenic dystonias has tremendously grown, their clinical boundaries are becoming increasingly blurry. The current phenotype-based classification may not reflect the molecular structure of the disease, urging the need for new systems based on shared biological pathways among dystonia-linked genes.

Efficacy and safety of nabiximols (Sativex(®)) on multiple sclerosis spasticity in a real-life Italian monocentric study.

Multiple sclerosis (MS) patients frequently suffer from limb spasticity and pain despite antispastic treatments. To investigate nabiximols efficacy and safety in a real-world monocentric Italian cohort, the following data were collected at baseline, week 4, 14 and 48: Ambulation Index (AI), 10-min walking test (10MWT), combined Modified Ashworth scale (cMAS), scores at numerical rating scale for spasticity (sNRS) and pain (pNRS). Responder status was defined as a ≥20 % reduction in sNRS after 4 weeks of treatment. 144 MS patients (123 progressive and 21 relapsing-remitting) complaining of moderate-to-severe spasticity (mean sNRS: 7.5) were included: 138 (95.8 %) completed the first month of therapy and were classified as follows-23.2 % were non-responders, 5.1 % were responders but discontinued treatment due to side effects, 71.7 % were responders with a mean 32 % reduction in sNRS (p < 0.001). In responders sNRS further decreased between 4 and 14 weeks (p = 0.03). Similarly, pNRS improvement was seen during the first month and between 4 and 14 weeks (p < 0.001 and p = 0.004, respectively). Moreover, at 4 weeks responders showed a significant (p < 0.05) improvement in cMAS, AI and 10MWT, which was maintained at 14 weeks. At 1-year follow-up, a benefit was still evident on spasticity and painful symptoms with a low drop-out rate. Confusion/ideomotor slowing, fatigue and dizziness were the most frequent side effects; no major adverse events were reported. Shorter disease duration at treatment start was associated with better response. This real-world study confirms nabiximols efficacy and safety in the treatment of MS-related spasticity and pain, which is maintained up to 48 weeks.