Epilepsy, speech delay, and mental retardation in facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common muscular dystrophies which is related to the deletion of tandem repeats on chromosome 4q35. Extramuscular features such as hearing loss, retinopathy, mental retardation, and epilepsy, may be observed in patients carrying large 4q35 deletions resulting in fragment sizes less than 12 kilobases (kb) (normal >35 kb). We report on a family affected by FSHD carrying a small 4q35 deletion and residual fragments length of 17 kb, presenting with epilepsy (three patients), speech delay (two), and mental retardation (one). In all patients semeiology of seizures and interictal EEG anomalies were congruent with a localization-related epilepsy possibly involving the temporal lobe. In conclusion, we provide further evidences that extramuscular findings such as epilepsy, speech delay, and mental retardation may occur in those patients carrying smaller 4q35 deletions, suggesting that a close correlation between 4q35 fragment size and clinical severity in FSHD is therefore not constant. Moreover, a review of the literature and our observations seem to suggest that focal epilepsies, likely related to the temporal lobe in the present family, represent the main type of epilepsy occurring in children with FSHD.