Paramyotonia congenita in a Slovak population: Genetic and pedigree analysis of 3 families.

BACKGROUND: Paramyotonia congenita is a non-dystrophic myotonia, in which muscle relaxation is delayed after voluntary or evoked contraction. This condition cannot be distinguished on the basis of symptoms and signs alone. It requires consideration of genetics as more than 100 mutations in the CLCN1 gene and at least 20 mutations in the SCN4A gene are associated with the clinical features of the non-dystrophic myotonias. Only a few families with the described features but no genetic testing have been reported in Slovakia. This prompted us to investigate genetic mutations in the SCN4A gene in 3 Slovak families clinically diagnosed with paramyotonia. SUBJECTS AND METHODS: Genomic DNA of the family members was extracted from peripheral blood and amplified by polymerase chain reaction. SCN4A variants were screened by Sanger sequencing. RESULTS: Our results revealed 2 potential disease-causing mutations present in the probands and affected family members - mutations c.3938C > T (p.T1313M) in two families and mutation c.2111C>T (p. T704M) in one family. CONCLUSION: Our results may help to identify genetic determinants as well as clarify genotype-phenotype relationships in patients with paramyotonia in Slovakia.

Epidemiology of Myasthenia Gravis in Slovakia in the Years 1977-2015.

PURPOSE: The objective of the study was to evaluate changes of epidemiological parameters in patients with myasthenia gravis (MG) in Slovakia during the period 1977-2015. METHODS: Data from medical records of MG patients registered in Slovakia were analyzed. Epidemiological rates (incidence, prevalence, mortality) were assessed for several periods to identify changes and drifts over the period of study. RESULTS: Out of 2,074 patients, 892 were males (43.0%) and 1,193 were females (57.0%). The thymoma associated MG (TAMG) was diagnosed in 123 patients (5.9%). The mean age at onset shifted from 35.8 years in 1977-1989 to 60.0 years in -2010-2015. The crude incidence increased from 0.36/100,000 in 1977-1989 to 1.74/100,000 in 2010-2015. The average annual incidence of TAMG was 0.05/100,000. Maximum increase of MG incidence was registered among the elderly (≥50 years), particularly in the group of patients in the age range 70-79 years (0.34/100,000 in 1977-1989→7.10/100,000 in 2010-2015) and 80-89 years (0.00/100,000 in 1977-1989→5.31/100,000 in 2010-2015). The crude MG prevalence on December 31, 2015 was 24.75/100,000. The average MG mortality was 0.27/100,000. CONCLUSION: The age at onset and incidence increased significantly over the study period due to marked increase of MG incidence in elderly, particularly over 70 years. Possible reasons for this trend are discussed.