Stiff child syndrome with mutation of DYT1 gene.

The authors report a Chinese boy with a DYT1 gene mutation having muscle stiffness, severe painful muscle spasm, myoclonus, and dystonia compatible with stiff child syndrome. Autoantibodies to glutamic acid decarboxylase (anti-GAD) were absent. His asymptomatic mother had a DYT1 mutation. His asymptomatic sister has diabetes mellitus and antibodies to glutamic acid decarboxylase but no DYT1 mutation.