SEVERE MENTAL-RETARDATION IN A YOUNG BOY WITH AN IN-FRAME DELETION INTHE DYSTROPHIN GENE

We report here a mentally retarded 32-month-old boy whose initial diag nosis was Angelman syndrome based on his clinical features. Cytogeneti c studies showed a normal karyotype. Due to an elevated level of serum creatine kinase activity, we performed analyses to rule out a myopath ic process. Although the electromyogram was normal, a few scattered ne crotic fibres were seen in the muscle biopsy. DNA and dystrophin studi es revealed an in-frame deletion in the 5' region of the dystrophin ge ne and an abnormal form of the protein product, consistent with a diag nosis of dystrophinopathy. We cannot totally rule out the possibility that this boy has the two separate conditions.