P146 – 2496: Clinical and genetic profile of two families with paroxysmal dyskinesia

Abstract

Objective Paroxysmal dyskinesia (PD) may present heterogeneous clinical features. Recent molecular studies have led to a new classification. We describe the different clinical and genetic features of two families with PD. Methods Clinical and genetic features description of two families with PD, from an index case. Results Case 1: a 5-year-old girl was diagnosed of occipital benign epilepsy at 5 months. From two years old she presented frequent paroxysms of choreoathetosis movements of lower limbs and facial dyskinesia lasting 5 minutes, mostly triggered by physical exertion or tiredness. She also suffered episodes of acute ataxia lasting several weeks. Her IQ was low average, with attention deficit. Her father had episodes of hemiplegic migraine triggered by exercise. Molecular study revealed 649dpC mutation (PRRT2 gen, 2nd exon), Paroxysmal Kinesigenic Dyskinesia (PKD). Currently she is partially controlled with carbamazepine. Case 2: a 3-year-old girl presented with attacks of hypotonia, left upper limb dystonic movements and drowsiness lasting 20 minutes, triggered by tiredness. Her mother was diagnosed with Paroxysmal Nonkinesigenic Dyskinesia (PNKD) and several mother's family members where also affected. Familial molecular study showed p.Ala7Val mutation (PNKD gen, 1st exon, 20 position). She was controlled with diazepam and remained asymptomatic. Conclusion PD is a heterogeneous group of diseases in which clinical characteristics and family history are critical for the diagnosis. PRRT2 mutations are responsible of PKD symptoms, induced by sudden movements or speed changes, but can also cause hemiplegic migraine, episodic ataxia and benign infantile seizures. Mutations on PNKD gen are linked to symptoms triggered by caffeine, alcohol, stress or fatigue.