Biallelic AOPEP Loss-of-Function Variants Cause Progressive Dystonia with Prominent Limb Involvement.

BACKGROUND: Monogenic causes of isolated dystonia are heterogeneous. Assembling cohorts of affected individuals sufficiently large to establish new gene-disease relationships can be challenging. OBJECTIVE: We sought to expand the catalogue of monogenic etiologies for isolated dystonia. METHODS: After the discovery of a candidate variant in a multicenter exome-sequenced cohort of affected individuals with dystonia, we queried online platforms and genomic data repositories worldwide to identify subjects with matching genotypic profiles. RESULTS: Seven different biallelic loss-of-function variants in AOPEP were detected in five probands from four unrelated families with strongly overlapping phenotypes. In one proband, we observed a homozygous nonsense variant (c.1477C>T [p.Arg493*]). A second proband harbored compound heterozygous nonsense variants (c.763C>T [p.Arg255*]; c.777G>A [p.Trp259*]), whereas a third proband possessed a frameshift variant (c.696_697delAG [p.Ala234Serfs*5]) in trans with a splice-disrupting alteration (c.2041-1G>A). Two probands (siblings) from a fourth family shared compound heterozygous frameshift alleles (c.1215delT [p.Val406Cysfs*14]; c.1744delA [p.Met582Cysfs*6]). All variants were rare and expected to result in truncated proteins devoid of functionally important amino acid sequence. AOPEP, widely expressed in developing and adult human brain, encodes a zinc-dependent aminopeptidase, a member of a class of proteolytic enzymes implicated in synaptogenesis and neural maintenance. The probands presented with disabling progressive dystonia predominantly affecting upper and lower extremities, with variable involvement of craniocervical muscles. Dystonia was unaccompanied by any additional symptoms in three families, whereas the fourth family presented co-occurring late-onset parkinsonism. CONCLUSIONS: Our findings suggest a likely causative role of predicted inactivating biallelic AOPEP variants in cases of autosomal recessive dystonia. Additional studies are warranted to understand the pathophysiology associated with loss-of-function variation in AOPEP. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Long-term efficacy and safety of rituximab in the treatment of neuromyelitis Optica Spectrum disorder.

Background: Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing, autoimmune, inflammatory astrocytopathy. Rituximab for B-cell suppression is a common treatment for NMOSD; however, large-scale randomised controlled trials are lacking. Objective: Evaluate long-term efficacy and safety of rituximab for NMOSD. Methods: Retrospective observational study of patients with NMOSD treated with rituximab. Annualised relapse rates (ARRs) before and during rituximab treatment were evaluated; Modified Rankin Scores (mRS) were measured as a marker of disability. Results: In total, 37 patients were included: 27 aquaporin-4-IgG-seropositive and 10 seronegative NMOSD. The predominant rituximab dosing regimen was an initial 1000 mg, split over two 500 mg infusions, two weeks apart, followed by single 500 mg doses. Over a median follow-up of 54 months, ARR for the whole cohort was 0.136 (95% CI 0.088-0.201), significantly lower than the pretreatment ARR of 0.366 (95% CI 0.271-0.483, p < 0.001). There was a significant reduction in ARR for the seropositive subgroup, but not seronegative. Significant improvement in mRS was seen post-treatment. Infections were reported in 32% of patients during follow-up; most were mild. Conclusion: Rituximab, at doses lower than traditionally used, may be an efficacious therapy for NMOSD, with a favourable safety profile.

An Australian State-Based Cohort Study of Autoimmune Encephalitis Cases Detailing Clinical Presentation, Investigation Results, and Response to Therapy.

Introduction: Autoimmune encephalitis is a disorder associated with antibodies directed against central nervous system proteins with variable clinical features. This study aims to add to knowledge of the disease by reporting the details of a cohort of patients with autoimmune encephalitis in Queensland, Australia. Methodology: We surveyed patients with autoimmune encephalitis diagnosed and managed through public hospitals in Queensland, Australia between 2010 and the end of 2019. Cases were identified via case detection through a centralized diagnostic neuroimmunology laboratory (Division of Immunology, HSQ Pathology Queensland Central Laboratory, Brisbane, Queensland, Australia) and a survey of neurologists. Data including demographic details, clinical presentation, investigation results, treatments including immune therapy and outcomes was collected. Results: Sixty cases of antibody positive autoimmune encephalitis were identified. Twenty-eight were of anti-NMDA-receptor encephalitis with other cases associated with antibodies against LGi1, Caspr2, glycine receptor, DPPX, GABAB receptor, IgLON5, GFAP, and SOX1. The number of diagnosed cases, especially of anti-NMDA-receptor encephalitis has markedly increased over the period 2017 to 2019. Clinical presentations were marked by heterogeneous symptom complexes and prolonged hospital admissions. Imaging studies were largely normal or non-specific. There was a response to immune therapy and a low mortality rate. Most cases affected by this disorder were left with ongoing symptoms associated with mild disability. Conclusion: Autoimmune encephalitis in Queensland, Australia is an increasingly common but complex clinical entity marked by heterogeneous presentations, response to immune therapy and outcome results marked by low mortality and incomplete recovery.

A prospective cohort study of prodromal Alzheimer's disease: Prospective Imaging Study of Ageing: Genes, Brain and Behaviour (PISA).

This prospective cohort study, "Prospective Imaging Study of Ageing: Genes, Brain and Behaviour" (PISA) seeks to characterise the phenotype and natural history of healthy adult Australians at high future risk of Alzheimer's disease (AD). In particular, we are recruiting midlife and older Australians with high and low genetic risk of dementia to discover biological markers of early neuropathology, identify modifiable risk factors, and establish the very earliest phenotypic and neuronal signs of disease onset. PISA utilises genetic prediction to recruit and enrich a prospective cohort and follow them longitudinally. Online surveys and cognitive testing are used to characterise an Australia-wide sample currently totalling over 3800 participants. Participants from a defined at-risk cohort and positive controls (clinical cohort of patients with mild cognitive impairment or early AD) are invited for onsite visits for detailed functional, structural and molecular neuroimaging, lifestyle monitoring, detailed neurocognitive testing, plus blood sample donation. This paper describes recruitment of the PISA cohort, study methodology and baseline demographics.

Experience from two decades of the Cambridge Rapid Access Neurology Clinic.

We report on the evolution of the rapid access neurology clinic (established in 1995) at Addenbrooke's Hospital, Cambridge. Annualised attendance data demonstrate an ever increasing demand, with primary headache disorders now accounting for more than 40% of referrals. Secondary causes of headache (including intracranial tumours, idiopathic intracranial hypertension, carotid or vertebral artery dissection and subdural haematomas) remain infrequent. In all such cases, there were additional diagnostic clues. The number of patients referred with problems related to chronic neurological diseases has fallen considerably, reflecting the roles of specialist nurses and clinics. Imaging investigation of choice shifted from computerised tomography scan (45 to 16%) towards magnetic resonance imaging (17 to 47%). Management is increasingly on an outpatient basis, often without the need for a follow-up appointment. The experience presented here should inform further development of rapid access neurology clinics across the UK and suggests the need for acute headache services, in line with those for transient ischaemic attack and first seizure.

Resolution of Othello Syndrome After Subthalamic Nucleus Deep Brain Stimulation in 3 Patients with Parkinson's Disease.

Psychiatric symptoms are historically thought a relative contraindication to DBS for advanced Parkinson's disease (PD). However, in the case of drug-induced mental illness, DBS may provide an acceptable alternative for the treatment of motor symptoms. This allows reduction of pharmacological dopaminergic therapy that might otherwise cause negative psychiatric consequences. For example, DBS is increasingly used to ameliorate specific complications of PD treatment, such as impulse control disorders. We present a series of 3 cases of young male patients who developed Othello syndrome (OS) during treatment with dopamine agonists. In each case, the OS resolved with withdrawal of the offending drug. Subsequent treatment with bilateral STN DBS improved motor symptoms and allowed reduction in their dopaminergic drug regimen. We therefore propose that drug-induced psychopathology may be an indication (rather than a contraindication) for DBS in selected cases.

Impulsivity and rapid decision-making for reward.

Impulsivity is a feature of many brain disorders. Although often defined as the predisposition to act with an inadequate degree of deliberation, forethought, or control, it has proven difficult to measure. This may in part be due to the fact that it is a multifaceted construct, with impulsive decisions potentially arising as a result of a number of underlying mechanisms. Indeed, a "functional" degree of impulsivity may even promote effective behavior in healthy participants in a way that can be advantageous under certain circumstances. Although many tasks have been developed to study impulsivity, few examine decisions made rapidly, for time-sensitive rewards. In the current study we examine behavior in 59 adults on a manual "Traffic Light" task which requires participants to take risks under time pressure, if they are to maximize reward. We show that behavioral variables that index rapid anticipatory responding in this paradigm are correlated with one, specific self-report measure of impulsivity: "lack of premeditation" on the UPPS Impulsive Behavior Scale. Participants who scored more highly on this subscale performed better on the task. Moreover, anticipatory behavior reduced significantly with age (18-79 years), an effect that continued to be upheld after correction for potential age differences in the ability to judge the timing of responses. Based on these findings, we argue that the Traffic Light task provides a parametric method to study one aspect of impulsivity in health and disease: namely, rapid decision-making in pursuit of risky, time-sensitive rewards.