The current mainstay treatment of Parkinson’s disease (PD) consists of dopamine replacement therapy which, in addition to causing several side effects, does not delay disease progression. The field of gene therapy offers a potential means to improve current therapy. The present review gives an update of the present status of gene therapy for PD. Both non-disease and disease modifying transgenes have been tested for PD gene therapy in animal and human studies. Non-disease modifying treatments targeting dopamine or GABA synthesis have been successful and promising at improving PD symptomatology in randomized clinical studies, but substantial testing remains before these can be implemented in the standard clinical treatment repertoire. As for disease modifying targets that theoretically offer the possibility of slowing the progression of disease, several neurotrophic factors show encouraging results in preclinical models (e.g., neurturin, GDNF, BDNF, CDNF, VEGF-A). However, so far, clinical trials have only tested neurturin, and, unfortunately, no trial has been able to meet its primary endpoint. Future clinical trials with neurotrophic factors clearly deserve to be conducted, considering the still enticing goal of actually slowing the disease process of PD. As alternative types of gene therapy, opto- and chemogenetics might also find future use in PD treatment and novel genome-editing technology could also potentially be applied as individualized gene therapy for genetic types of PD.

Background Mitochondrial alanyl-tRNA synthetase 2 gene ( AARS2 ) related disease is a rare genetic disorder affecting mitochondrial metabolism, leading to severe cardiac disease in infants or progressive leukodystrophy in young adults. The disease is considered ultra-rare with only 39 cases of AARS2-leukodystrophy previously reported. Case presentation We present the case of a young man of consanguineous heritage suffering from cognitive decline and progressive spasticity as well as weakness of the proximal musculature. Utilizing MRI and whole genome sequencing, the patient was diagnosed with a homozygous AARS2 missense variant (NM_020745.3:c.650C > T; p.(Pro217Leu)) and a homozygous CAPN3 variant (NM_000070.2: c.1469G > A; p.(Arg490Gln)), both variants have previously been identified in patients suffering from AARS2 related leukodystrophy and limb-girdle muscular dystrophy, respectively. Conclusions This case report presents a case of homozygous AARS2 leukodystrophy and serves to highlight the importance of whole genome sequencing in diagnosing rare neurological diseases as well as to add to the awareness of adult onset leukodystrophies.

BackgroundVaroglutamstat (PQ912), a small molecule glutaminyl cyclase (QPCT) inhibitor, reduces the brain levels of pyroglutamate‐3‐Aβ (N3pE‐Aβ), a toxic Aβ variant shown to play a pivotal role in the development and progression of Alzheimer’s disease (AD). Encouraging results reported in a prior Phase 2a study (NCT02389413) led to the initiation of a state‐of‐the‐art Phase 2b trial investigating multiple cognitive, safety and biomarker endpoints.MethodsVIVIAD (NCT04498650) is a multicentre randomized, placebo‐controlled, double‐blind, parallel group dose finding Phase 2b study in patients with cognitive impairment (MCI) and mild AD. Objectives are to evaluate the longterm efficacy (primary endpoint Cogstate NTB), safety and tolerability of oral varoglutamstat. The study will recruit 250 patients. The first 90 patients are randomised 1:1:1 (600 mg twice daily, (BID) or 300 mg BID varoglutamstat or placebo BID). An independent DSMB will unblind safety results after 90 patients have completed 24 weeks of treatment in June 2022 and decide on the varoglutamstat dose to be carried forward. The data remain blinded outside the DSMB. After the DSMB decision, all patients will be randomised 1:1 between the final dose of varoglutamstat and placebo and continue treatment up to 48‐96 weeks dependent on study entry date.ResultsThe study is currently enrolling patients in 22 AD study centers in 5 European countries (160 patients are randomised as of April 25, 2022). The safety data providing the base for the DSMB dose decision, the DSMB decision itself and the baseline characteristics of the patients enrolled into the trial so far will be reported at AAIC.ConclusionThe state‐of‐the art Phase 2b study VIVIAD is designed to yield important results in early AD for varoglutamstat, the first small molecule and only project in clinical development selectively targeting the de novo production of neurotoxic N3pE‐Aβ. The DSMB decision represents an important milestone within the Phase 2b study as it will recommend the dose of varoglutamstat considered to be safe for being carried forward to the study completion.