Distinctive phenotype in a girl with Rett syndrome and a novel 25 bp deletion mutation in exon 4 (c.881_905del25, nm_004992.3) of the MECP2 gene

Rett syndrome is a pervasive developmental disorder with a variable clinical presentation, which is caused by point mutations orlarge deletions/duplications in the X-linked methyl-CpG-binding protein 2 (MECP2) gene. The aim is to describe variation in theclinical course related to the mutation identifi ed in exon 4 of the MECP2 gene. Retrospective review of data, electroencephalographyand treatment was done in a 19-year-old girl previously diagnosed with a MECP2 gene mutation. Born after an uneventful pregnancy,the female patient’s growth and psychomotor development were normal, except for delayed speech. At the age of 3 years,tonic-clonic seizures started and at the age of 3.5 years autistic behavior was observed, followed by rapid mental deterioration, lossof speech and motor skills, with periods of hyperventilation. At the age of 5 years, she showed occasionally „hand-washing“movements. Extensive neuro-metabolic investigation was nondiagnostic. Genetic analysis revealed a novel 25 bp deletion mutationin exon 4 (c.881_905del25) of the MECP2 gene. Until now, multiple epileptic seizure types, refractory to all antiepileptic polytherapyand with normal video EEG background, have occurred daily. She is spastic and ataxic, but still able to walk slowly with awide based gait. In this female patient, the onset of symptoms manifested much later than encountered in typical cases ofRett syndrome. Epilepsy with daily frequency is however drug resistant. Unexpectedly, she is still able to walk at the age of 19years. A genotype-phenotype correlation is suspected.

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