1. Three families with a form of myotonia (muscle stiffness due to membrane hyperexcitability) clinically distinct from previously classified myotonias were examined. The severity of the disease greatly differed among the families. 2. Three dominant point mutations were discovered at the same nucleotide position of the SCN4A gene encoding the adult skeletal muscle Na+ channel alpha-subunit. The...

The authors describe an Italian kindred with nine individuals affected by hyperkalaemic periodic paralysis associated with paramyotonia congenita (hyperPP/PMC). Periodic paralysis was particularly severe, with several episodes a day lasting for hours. The onset of episodes was unusually early, beginning in the first year of life and persisting into adult life. The paralytic episodes were refrac...

INTRODUCTION Two previously reported Norwegian patients with painful muscle cramps and giant myotonic discharges were genotyped and compared with those of members of 21 families harboring the same mutation. METHODS Using primers specific for SCN4A and CLCN1, the DNA of the Norwegian family members was amplified and bidirectionally sequenced. Clinical and neurophysiological features of other f...

A 48-year-old man presented with episodic paraplegia and stiffness of hands, face, and tongue, along with eyelid myotonia when exposed to cold temperature, which he had since childhood. Eyelid myotonia was evoked either by exposure to cold weather (video on the Neurology® Web site at www.neurology.org and figure 1) or by forceful eye closure. Myotonia was elicited with percussion of the tongue ...

وراثت مقاومت سفیدبالک گلخانه، Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae)، به دو ترکیب ایمیداکلوپرید و کلرپایریفوس مورد مطالعه قرار گرفت. در این پژوهش، از جمعیت فیلستان ورامین (FL) عنوان والد مقاوم فردیس کرج (FR) حساس استفاده شد. مقدار ترتیب حدودا 62/13 91/14 برابر بود. عدم وجود اختلاف معنی‌دار LC50 روی تلاقی‌های F1 (R♂×S♀) Fʹ1 (R♀×S♂) نشان داد که T. نوع اتوزومی (غیرجنسی) است. ه...

Paramyotonia congenita, the major characteristics of which are cold-induced and exercise-induced myotonia, is an autosomal-dominant muscle disease which is classified into one of a group of muscle diseases, so-called muscle "sodium channelopathies" caused by missense mutations in the gene coding for the skeletal muscle sodium channel a-subunit (SCN4A) (1-4). Such muscle sodium channelopathies s...