Angelman syndrome: Mimicking conditions and phenotypes

The diagnosis of Angelman syndrome (AS) can be confirmed by genetic laborat ory in about 80% of cases. In 20%, the diagnosis remains clinical, but ofte n there is uncertainty about the correctness of the clinical diagnosis and alternative diagnosis may be investigated. In evaluating individuals for AS in our center since 1989, we have encountered several mimicking conditions , and additional ones have been reported in the literature. Mimicking condi tions can be grouped into the areas of chromosome, single gene, and symptom complex anomalies. Microdeletions or microduplications include chromosome regions 2,4,17, 22, and 15, Single gene conditions include methylene tetrah ydrofolate reductase deficiency (MTHFR), Rett syndrome, alpha-thalassemia r etardation syndrome (ATR-X), and Gurrieri syndrome. Symptom complexes inclu de cerebral palsy, static encephalopathy, Lennox-Gastaut syndrome, autism s pectrum disorder, pervasive developmental delay (PDD), and mitochondrial di sorders. We present a review of these mimicking disorders to increase the a wareness about conditions that can lead to an incorrect clinical diagnosis of AS. (C) 2001 Wiley-Liss, Inc.