G.P.76 - A third case of congenital myasthenic syndrome caused by mutations in SCN4A

Abstract

The objective of this study is to analyse the epidemiological data and clinical features in patients (p.) with very late-onset myasthenia gravis (VLOMG) > 70 yrs in Slovakia. In the Slovak MG Register 1950 (p.) are registered (1978–2014). We analysed p. with MG onset > 70 yrs. Collected data for descriptive longitudinal study were age at onset, sex, year of MG onset, year of MG diagnosis, AChR and MuSK antibodies, thymoma, clinical symptoms, and comorbidities. We found VLOMG in 353 p. (18.1%), 181 females (F) 51.3%, 172 males (M) 48.7%. The mean age at onset was 75.2 yrs, F 75.7, M 74.5. 289 p. had MG onset between 70 and 79 yrs (142 F, 147 M). At the age >80 yrs 64 p. (39 F, 25 M) had their onset. Overall incidence of VLOMG had an increase from 0.32/105 in 1978 to 4.29/105 in 2014 (mean 2.52/105). 163 p. were alive on Dec. 31, 2014, giving an overall prevalence of 33.58/105, 71 M (41.29/105), 92 F (29.35/105). In the presentation we will give also data of age-specific incidence and prevalence for both sexes. Ocular symptoms were initial in 73 p. (20.7%), bulbar symptoms in 159 p. (45.0%). 93.6% p. had AChR positive MG, 0.7% p. MuSK positive MG, 5.7% p. double-seronegative MG. 12 p. (3.4%) had thymoma. VLOMG occurs in 353 p. (18.1%), with almost equal frequency in M and F. The mean age-specific incidence is higher for M in comparison to F due to shorter life-expectancy in M and thereby lower representation of M > 70, mainly in 80–89 yrs. Therefore, also the age-specific prevalence of VLOMG is higher in M, though the majority of surviving patients are F. In VLOMG p. AChR positivity dominates (93.6%), bulbar symptoms are often present at onset, and p. have higher occurrence of age-specific comorbidities.