Age is an important independent modifier of SCA3 phenotype severity

IL-4/STAT6 axis observed to reverse proliferative defect in SCA3 patient-derived neural progenitor cells

Spinocerebellar ataxia 3 (SCA3) is an incurable, neurodegenerative genetic disorder that leads to progressive cerebellar ataxia and other parkinsonian-like pathologies because of loss of cerebellar neurons. The role of an expanded polyglutamine aggregate on neural progenitor cells is unknown. Here, we show that SCA3 patient-specific induced neural progenitor cells (iNPCs) exhibit proliferative defects. Moreover, SCA3 iNPCs have reduced autophagic expression compared to control. Furthermore, although SCA3 iNPCs continue to proliferate, they do not survive subsequent passages compared to control iNPCs, indicating the likelihood that SCA3 iNPCs undergo rapid senescence. Exposure to interleukin-4 (IL-4), a type 2 cytokine produced by immune cells, resulted in an observed increase in expression of autophagic programs and a reduction in the proliferation defect observed in SCA3 iNPCs. Our results indicate a previously unobserved role of SCA3 disease ontology on the neural stem cell pool and a potential therapeutic strategy using IL-4 to ameliorate or delay disease pathology in the SCA3 neural progenitor cell population.

Polyglutamine-Expanded Ataxin-3: A Target Engagement Marker for Spinocerebellar Ataxia Type 3 in Peripheral Blood

BACKGROUND

Spinocerebellar ataxia type 3 is a rare neurodegenerative disease caused by a CAG repeat expansion in the ataxin-3 gene. Although no curative therapy is yet available, preclinical gene-silencing approaches to reduce polyglutamine (polyQ) toxicity demonstrate promising results. In view of upcoming clinical trials, quantitative and easily accessible molecular markers are of critical importance as pharmacodynamic and particularly as target engagement markers.

OBJECTIVE

We aimed at developing an ultrasensitive immunoassay to measure specifically polyQ-expanded ataxin-3 in plasma and cerebrospinal fluid (CSF).

METHODS

Using the novel single molecule counting ataxin-3 immunoassay, we analyzed cross-sectional and longitudinal patient biomaterials.

RESULTS

Statistical analyses revealed a correlation with clinical parameters and a stability of polyQ-expanded ataxin-3 during conversion from the pre-ataxic to the ataxic phases.

CONCLUSIONS

The novel immunoassay is able to quantify polyQ-expanded ataxin-3 in plasma and CSF, whereas ataxin-3 levels in plasma correlate with disease severity. Longitudinal analyses demonstrated a high stability of polyQ-expanded ataxin-3 over a short period. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Clinical and genetic profile in index patients with spinocerebellar ataxia type 3 in Indonesia: case report

Spinocerebellar ataxia (SCA) is an autosomal dominant hereditary disease with progressive course, and no causal therapy. Diagnostics are still challenging, due to facility and protocols, and so as in Indonesia. As a national referral center, Dr. Hasan Sadikin Central General Hospital has received a lot of patients from all over Indonesia, particularly from Western Java. Study related to SCA (including clinical and genetic profile) is still limited in Indonesia. We identified index patients from three families with ataxia, hence intend to determine their clinical and genetic pattern.

The hereditary pattern is autosomal dominant. Scale for the assessment and rating of ataxia (SARA) shows mild and moderate ataxia. Inventory of non-ataxia signs (INAS) scores of the patients were 3, 5 and 6. Montreal cognitive assessment-Indonesian version (MOCA-INA) shows only one patient has mild cognitive impairment, despite young age. Barthel index shows 1 subject has moderate dependency. Mutation in Ataxin3 polyQ repeats shows pathologically long CAG repeats, 72,10; 72,10; and 72,23 respectively in mutant and wild type allele.

We diagnosed the index patients with spinocerebellar ataxia type 3. This study is the first case series study in Indonesia. The hereditary pattern is clearly shown as an autosomal dominant ataxia. The clinical and genetic profile was varied, and the symptom is progressive and deteriorates overtime, including wide based gait, speech problem, motor and sensor complaint, and cognitive decline complaint. Despite the same polyQ stretch length, the onset and clinical characteristics of patients are diverse.