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.

Second mutation in PARK2 is absent in patients with sporadic Parkinson's disease and heterozygous exonic deletions/duplications in parkin gene.

AIM OF THE STUDY: Mutations in PARK2 are one of the causes of Parkinson's disease (PD). Deletions and duplications/triplications of one exon or exon groups account for a large proportion of mutations in the gene. At the present time, it is still not fully clear whether heterozygous mutations cause the development of PD. Our study aimed at conducting screening for mutations in PARK2 in patients with a sporadic form of PD to clarify the role of PARK2 in the development of PD. MATERIALS AND METHODS: The cohort of 327 patients with PD was screened by quantitative real-time polimerase chain reaction (PCR) with subsequent Sanger sequencing. RESULTS: It was found that a sufficiently large proportion of these patients (21 patients, 6.4%) were carriers of heterozygous deletions or duplications in PARK2. Analysis of PARK2 exon rearrangement carriers for the presence of point mutations in PARK2 did not reveal any variants with pathogenic significance. CONCLUSIONS: Thus, our data indicate that heterozygous deletions and duplications can play an important role in the pathogenesis of PD and can be considered as dominant mutations with low penetrance.

Genetic studies of Russian patients with amyotrophic lateral sclerosis.

Our objective was to search for mutations in genes SOD1, TARDBP, C9orf72, ANG, ATXN2 and VEGF in Russian patients with amyotrophic lateral sclerosis (ALS). A group of 208 Russian patients with ALS was examined. Molecular genetic analysis was conducted using direct sequencing, fragment analysis, and real-time PCR. We found eight different point mutations in the SOD1 gene, with the frequency of mutations being 50% in familial ALS and 3% in sporadic ALS. No mutations were found in exon 6 of the TARDBP gene; however, deletion c.715-126delG in intron 5 of TARDBP was over-represented in ALS patients compared to controls (38% vs. 26.6%; χ(2 )= 13.17; p = 0.002). Hexanucleotide repeat expansion of the C9orf72 gene was revealed in 2.5% of sporadic ALS patients. Mutations in the ANG gene were identified in 1.5% of sporadic ALS patients. The presence of an intermediate number (28-33) of GAC repeats in the ATXN2 gene was observed significantly more often in the study group compared to the control group (5% vs. 1.7%; χ(2 )= 3.89; p = 0.0486). In the cohort examined, we found an association between the disease and the risk A-allele and the A/A genotype at the -2578С/А locus of the VEGF gene. In conclusion, we determined for the first time the genetic basis of ALS in a Russian population.