AbstractThe aim of this study was to describe the clinical features of a large Serbian family with paroxysmal nonkinesigenic dyskinesia (PNKD) and one of the two previously described mutations in the Myofibrillogenesis regulator 1 gene (MR‐1), which causes an alanine‐to‐valine substitution at position 9. In 5 examined out of 12 affected family members, attacks of dyskinesias appeared in the first 6 months of life. Both frequency and severity of attacks showed an age‐dependent incremental–decremental pattern with a peak between 13 to 15 years of age. They were frequently precipitated by stress, caffeine, fever, hunger, tiredness, as well as abrupt changes in temperature. Three of our patients differentiated two types of attacks: mild (120–180 minutes), with a predominance of functionally insignificant choreoathetoid movements, and severe (∼ 15–30 minutes), characterized by disabling dystonic and choreic movements of the extremities, trunk, and face. Sleep was the most reliable factor to discontinue an attack. This Serbian family further demonstrates that recurrent MR‐1 mutations are associated with PNKD worldwide, which will affect genetic testing. © 2006 Movement Disorder Society