Malignant refractory epilepsy in identical twins mosaic for a supernumerary ring chromosome 19.

We report identical twins with supernumerary ring chromosome 19 mosaicism, who had severe refractory epilepsy at an early age. The epilepsy was dominated largely by severe life-threatening tonic seizures. Both twins died, likely as a consequence of their severe epilepsy. They displayed no dysmorphic features. Eight cases of ring chromosome 19 have been reported in the literature, all to our knowledge without epilepsy. The clinical picture of these twins emphasizes the importance of carrying out a karyotype study on patients with early-onset epilepsy even in the absence of dysmorphic features.