Case report: A novel CACNA1S mutation associated with hypokalemic periodic paralysis.

Background: Hypokalemic periodic paralysis (HypoKPP) is a rare neuromuscular genetic disorder causing recurrent episodes of flaccid paralysis. Most cases are associated with CACNA1S mutation, causing defect of calcium channel and subsequent impairment of muscle functions. Due to defined management approaches early diagnosis is crucial for promptly treatment and prevention new attacks. Materials and methods: We report a case of HypoKPP associated with previously unreported mutation in CACNA1S gene (p.R900M). Molecular modeling of CaV1.1 was applied to evaluate its pathogenicity. Results: As a patient referred between attacks neurological status, laboratory and neurophysiological examination were unremarkable. Molecular modeling predicted that the p.R900M mutation affects the process of calcium channels activation. Conclusion: Novel CACNA1S mutation, associated with HypoKPP was identified. Monte-Carlo energy minimization of the CaV1.1 model supported the association of this mutation with this disease.

Mutation analysis of the TATA box-binding protein (TBP) gene in Russian patients with spinocerebellar ataxia and Huntington disease-like phenotype.

OBJECTIVE: We aimed to analyze the occurrence and clinical and genetic characteristics of spinocerebellar ataxia type 17 (SCA17) among Russian patients with progressive cerebellar ataxia or Huntington disease-like phenotype. METHODS: Genetic analysis of CAG/CAA repeats in TBP gene was carried out in 217 patients, including 153 patients with progressive unspecified ataxia and 64 patients with Huntington disease-like phenotype. SCA types 1, 2, 3, 6 and 8, Friedreich's ataxia, CANVAS and Huntington disease were preliminarily excluded. RESULTS: Six unrelated patients with SCA17 (2.8 %) were identified (43-57 CAG/CAA repeats in TBP gene). Two patients had a positive family history. Age at the disease onset ranged from 15 to 47 years. The core clinical syndrome included progressive cerebellar ataxia, dysarthria, movement disorders, cognitive impairment, and psychiatric symptoms. One patient had epilepsy with rare generalized tonic-clonic seizures. Another patient with diffuse muscle atrophy and small expansion size (43 CAG/CAA repeats) had myopathic changes in skeletal muscles on EMG study. We also described a patient with a large expansion size of 57 CAA/CAG repeats with early onset and rapid disease progression. CONCLUSION: SCA17 is a relatively rare cause of progressive disorders with ataxia and chorea, but it should be considered in the spectrum of differential diagnosis in such patients. Most of our SCA17 cases were sporadic which should be kept in mind when planning genetic testing in patients with spinocerebellar ataxia and chorea.

POLG-associated ataxias can represent a substantial part of recessive and sporadic ataxias in adults.

OBJECTIVE: We aimed to analyze prevalence, clinical, and genetic characteristics of the POLG-associated ataxias in a cohort of recessive and sporadic ataxias in adults with previously excluded acquired ataxias. METHODS: We did a retrospective analysis of the medical records of 74 patients older than 18 years referred to the Research Center of Neurology between 2012 and 2019 with progressive sporadic or autosomal recessive ataxia with onset before 50 years of age. A stepwise approach in genetic testing was used. All patients with genetically confirmed POLG-associated disorders underwent clinical, biochemical, electrophysiological, and neuroimaging assessments. RESULTS: In our cohort of 74 adult patients with autosomal recessive and sporadic ataxias, POLG-related disease was identified in 11 individuals (14.9 %). The median age of onset was 30 years. One patient had a positive family history. The core clinical syndrome included external ophthalmoparesis, cerebellar signs, and sensory neuropathy. In all patients, the Montreal Cognitive Assessment score was less than 26. All but 3 patients had specific brain MRI changes. Mutation spectrum of the POLG gene in our cohort is discussed. CONCLUSION: Our study shows that POLG-associated ataxias comprise a significant part of the recessive and sporadic ataxias in adults in the Russian population after excluding acquired causes of ataxic disorders. We suggest first screening patients with specific clinical and (or) neuroimaging features for the population-specific common POLG mutations, followed by the NGS panel testing where necessary. In future clinical studies, thorough cognitive and neuropsychiatric profiling is needed to complete the phenotype of the POLG-related disorders.

Plasma oligomeric alpha-synuclein is associated with glucocerebrosidase activity in Gaucher disease.

BACKGROUND: The link between Parkinson's disease (PD) and Gaucher disease (GD), the most common lysosomal storage disease associated with loss of glucocerebrosidase (GBA) activity, can be explained by abnormal accumulation of oligomeric alpha-synuclein (α-Syn) species resulting from mutations in the GBA gene. However, in GD, the relationship between GBA activity and α-Syn accumulation in biological fluids has not been investigated. METHODS: We analyzed plasma oligomeric α-Syn levels, leucocyte GBA activity, and plasma chitotriosidase activity in 21 patients with GD. RESULTS: Negative correlation between plasma oligomeric α-Syn levels, and leucocyte GBA activity was observed in patients with GD (R(2) = 0.487; P < 0.001). CONCLUSION: The decrease in GBA activity may influence α-Syn oligomerization, explaining the high risk of PD development in GD patients. © 2015 International Parkinson and Movement Disorder Society.