This compilation arises from contributions made to the seventh postgraduate course in paediatric neurology held in Pavia, Italy under the auspices of the Mariani Foundation in co-operation with the National Neurologic Institute of Milan. The course concentrated on three main areas: the impact of molecular biology and molecular genetics on aetiology, advances in our understanding pathogenesis, and finally therapy. The choice of the subject was suggested by the remarkable progress has been made in this field during the last decade, mostly due to the recent advances in genetics which now enable a new nosographic approach as well as different diagnostic strategies. Part of this work is dedicated to the rehabilitation of patients affected by neuromuscular diseases.