Spectrum of inherited myotonias and periodic paralyses

ABSTRACT

To study the spectrum of inherited myotonias and periodic paralyses in Saudi Arabia. Forty nine patients with electromyography confirmed myotonic disorders and periodic paralysis were seen at King Khalid University Hospital between January 1985 and January 1998. Data was analyzed and available patients reassessed in order to document fully the various clinical features and ascertain the diagnosis and mode of inheritance. There are 11 patients with Thomsen's disease; 21 patients with Becker's disease, most of them had an early onset of 2-3 years; 12 patients with myotonic dystrophy; and 5 Filipino patients with periodic paralyses, 3 of them with associated thyrotoxicosis. The spectrum of these disorders is similar to that described in western reports, apart from 2 main differences. First, is the clear predominance of Becker's disease [45%] which has a lower age of onset. This is probably the result of the high local consanguinity rate. Secondly is the absence of periodic paralysis in Saudis, while some patients had associated thyrotoxicosis, which is well recognized in Far East populations. These disorders are poorly studied in Saudi Arabia and deserve further epidemiological and genetic assessment