Therapeutic inertia in relapsing-remitting multiple sclerosis.

BACKGROUND: Therapeutic inertia (TI) is defined as a failure to initiate or intensify treatments despite evidence of disease activity. Its prevalence and determining factors in Relapsing-Remitting Multiple Sclerosis (RRMS) patients in Portugal are not known. The main objective of this work was to ascertain the prevalence of TI in RRMS and its determining factors. METHODS: We conducted a multicentre retrospective observational study of RRMS patients followed in MS Clinics of six Portuguese hospitals with at least one medical appointment in 2018. TI was defined as the absence of treatment initiation or intensification when therapeutic goals were unmet, that is when there was evidence of disease activity based on the definition of "no evidence of disease activity" (NEDA) which refers to absence of clinical relapses, absence of disease progression measured by expanded disability status scale (EDSS) and absence of new disease activity (new T2 lesions/enhancing lesion) on magnetic resonance imaging (MRI) over the period of observation. RESULTS: We included 427 patients with RRMS meeting inclusion criteria, 69.6% females, with a mean age of 41.66 years old. The mean age at diagnosis was 33.17 years old and the average number of years since diagnosis was 8.72. MS relapses were reported on 54 patients. Moderate to severe relapses were reported in 59.3%. Median EDSS score was 1.5. Intention to get pregnant was explicit in 39 patients, representing 18.8% of the women at childbearing age. Among the 365 patients who had an MRI, 23.8% had new T2 lesions and 7.4% had enhancing lesions. Regarding DMT, 72.8% were treated with interferon, glatiramer acetate, teriflunomide, or dimethyl fumarate, 20.6% were under fingolimod, natalizumab, rituximab, and cladribine, and the remaining 6.6% were without treatment. Adverse events were reported in 12.9% of patients, and 10.1% mentioned preferences regarding the treatment. TI was present in 80 (18.7%) patients, representing 54.8% of those with potential to inertia. Patients with a radiologically less active disease, who were already on a DMT and who had no adverse events from their current treatment were more likely to have TI (p<0,05). Also, patients followed in centers classified as higher level of care (level 1) had more TI compared with patients followed in centers of levels 2 and 3. CONCLUSION: TI was present in 1 in 5 patients, exceeding half of the sample with the potential to inertia, corroborating the high prevalence of TI in other studies. The determining factors of TI were the absence of relapses or the occurrence of mild relapses, being already on DMT, absence of adverse events, and follow-up in higher care level centers. TI is a topic rarely addressed in MS and this work highlights the importance of therapeutic optimization in these patients. Further studies should be held to explore the factors that influence TI once they have a great impact on therapeutic decisions.

Increasing involvement of CAPN1 variants in spastic ataxias and phenotype-genotype correlations.

Spastic ataxias are rare neurogenetic disorders involving spinocerebellar and pyramidal tracts. Many genes are involved. Among them, CAPN1, when mutated, is responsible for a complex inherited form of spastic paraplegia (SPG76). We report the largest published series of 21 novel patients with nine new CAPN1 disease-causing variants and their clinical characteristics from two European university hospitals (Paris and Stockholm). After a formal clinical examination, causative variants were identified by next-generation sequencing and confirmed by Sanger sequencing. CAPN1 variants are a rare cause (~ 1.4%) of young-adult-onset spastic ataxia; however, together with all published cases, they allowed us to better describe the clinical and genetic spectra of this form. Truncating variants are the most frequent, and missense variants lead to earlier age at onset in favor of an additional deleterious effect. Cerebellar ataxia with cerebellar atrophy, dysarthria and lower limb weakness are often associated with spasticity. We also suggest that cognitive impairment and depression should be assessed specifically in the follow-up of SPG76 cases.

Determinants of age at onset in a Portuguese cohort of autosomal dominant spastic paraplegia.

BACKGROUND: Hereditary spastic paraplegias present a high variability of age at onset, ranging from childhood to older age. Our objective was to identify the determinants of age at onset in autosomal dominant HSP (AD-HSP) in a large cohort of patients and families. METHODS: We included 239 patients from 89 families identified in the Portuguese multisource population-based survey of hereditary ataxias and spastic paraplegias. Patients were systematically examined by a team of neurologists, admitted for complete clinical workup and tested for SPG3, SPG4 and SPG31. RESULTS: Average age at onset was 38.2 years in the first generation, 32.3 years in the second and 17.5 years in the third, with a significant decrease of average age at onset between generations (p < .001). A decrease in the average age at onset was seen in all genotypes (SPG4: p < .001; SPG3: p = .15; SPG31: p < .001). In families with more than one generation (n = 38), this decrease was observed in 78.9%. In multivariate linear regression model, the independent effect of generation in anticipation of age at onset was confirmed (p < .001), adjusting for family, genotype and mutation. We also observed a significant lower age at onset in patients with missense versus truncating mutations (p = .015) in patients with SPG4. CONCLUSION: These results confirm the impact of missense mutations in an earlier age at onset in SPG4 patients. Even though the age at onset could be affected by subjectivity, our results are consistent with the presence of an anticipation phenomenon in AD-HSP.

Massive sequencing of 70 genes reveals a myriad of missing genes or mechanisms to be uncovered in hereditary spastic paraplegias.

Hereditary spastic paraplegias (HSP) are neurodegenerative disorders characterized by lower limb spasticity and weakness that can be complicated by other neurological or non-neurological signs. Despite a high genetic heterogeneity (>60 causative genes), 40-70% of the families remain without a molecular diagnosis. Analysis of one of the pioneer cohorts of 193 HSP families generated in the early 1990s in Portugal highlighted that SPAST and SPG11 are the most frequent diagnoses. We have now explored 98 unsolved families from this series using custom next generation sequencing panels analyzing up to 70 candidate HSP genes. We identified the likely disease-causing variant in 20 of the 98 families with KIF5A being the most frequently mutated gene. We also found 52 variants of unknown significance (VUS) in 38% of the cases. These new diagnoses resulted in 42% of solved cases in the full Portuguese cohort (81/193). Segregation of the variants was not always compatible with the presumed inheritance, indicating that the analysis of all HSP genes regardless of the inheritance mode can help to explain some cases. Our results show that there is still a large set of unknown genes responsible for HSP and most likely novel mechanisms or inheritance modes leading to the disease to be uncovered, but this will require international collaborative efforts, particularly for the analysis of VUS.

Autosomal dominant spastic paraplegias: a review of 89 families resulting from a portuguese survey.

IMPORTANCE: Hereditary spastic paraplegias (HSPs) are a group of diseases caused by corticospinal tract degeneration. Mutations in 3 genes (SPG4, SPG3, and SPG31) are said to be the cause in half of the autosomal dominant HSPs (AD-HSPs). This study is a systematic review of families with HSP resulting from a population-based survey. Novel genotype-phenotype correlations were established. OBJECTIVE: To describe the clinical, genetic, and epidemiological features of Portuguese AD-HSP families. DESIGN: Retrospective medical record review. SETTING: A population-based systematic survey of hereditary ataxias and spastic paraplegias conducted in Portugal from 1993 to 2004. PARTICIPANTS: Families with AD-HSP. MAIN OUTCOME MEASURE: Mutation detection in the most prevalent genes. RESULTS: We identified 239 patients belonging to 89 AD-HSP families. The prevalence was 2.4 in 100 000. Thirty-one distinct mutations (26 in SPG4, 4 in SPG3, and 1 in SPG31) segregated in 41% of the families (33.7%, 6.2%, and 1.2% had SPG4, SPG3 and SPG31 mutations, respectively). Seven of the SPG4 mutations were novel, and 7% of all SPG4 mutations were deletions. When disease onset was before the first decade, 31% had SPG4 mutations and 27% had SPG3 mutations. In patients with SPG4 mutations, those with large deletions had the earliest disease onset, followed by those with missense, frameshift, nonsense, and alternative-splicing mutations. Rate of disease progression was not significantly different among patients with SPG3 and SPG4 mutations in a multivariate analysis. For patients with SPG4 mutations, disease progression was worst in patients with later-onset disease. CONCLUSIONS AND RELEVANCE: The prevalence of AD-HSP and frequency of SPG3 and SPG4 mutations in the current study were similar to what has been described in other studies except that the frequency of SPG4 deletions was lower. In contrast, the frequency of SPG31 mutations in the current study was rare compared with other studies. The most interesting aspects of this study are that even in patients with early-onset disease the probability of finding a SPG4 mutation was higher than for patients with SPG3 mutations; there was no difference in disease progression with genotype but an association with the age at onset; 7 new SPG4 mutations were identified; and for the first time, to our knowledge, the nature of the SPG4 mutations was found to predict the age at onset.

Alu elements mediate large SPG11 gene rearrangements: further spatacsin mutations.

PURPOSE: Hereditary spastic paraplegias compose a group of neurodegenerative disorders with a large clinical and genetic heterogeneity. Among the autosomal recessive forms, spastic paraplegia type 11 is the most common. METHODS: To better understand the spastic paraplegia type 11 mutation spectrum, we studied a group of 54 patients with hereditary spastic paraplegia. Mutation screening was performed by PCR amplification of SPG11 coding regions and intron boundaries, followed by sequencing. For the detection of large gene rearrangements, we performed multiplex ligation-dependent probe amplification. RESULTS: We report 13 families with spastic paraplegia type 11 carrying either novel or previously identified mutations. We describe a complex entire SPG11 rearrangement and show that large gene rearrangements are frequent among patients with spastic paraplegia type 11. Moreover, we mapped the deletion breakpoints of three different large SPG11 deletions and provide evidence for Alu microhomology-mediated exon deletion. CONCLUSION: Our analysis shows that the high number of repeated elements in SPG11 together with the presence of recombination hotspots and the high intrinsic instability of the 15q locus all contribute toward making this genomic region more prone to large gene rearrangements. These findings enlarge the amount of data relating repeated elements with neurodegenerative disorders and highlight their importance in human disease and genome evolution.