Short report Homozygosity for MECP2 gene in a girl with classical Rett syndrome Daniela Karall a, * , Edda Haberlandt a , Sabine Scholl-Bu ¨rgi a , Sara Baumgartner a , Montserrat Naudo ´ b , Loreto Martorell b a Clinical Department of Pediatrics, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck, Austria b Molecular Genetics Section, Hospital Sant Joan de De ´u, Barcelona, Spain Received 15 May 2007; accepted 21 July 2007 Available online 6 August 2007 Abstract We report a 21 year-old girl with classical Rett syndrome (RS) based on clinical diagnosis. The mo- lecular testing of MECP2 gene revealed that the patient is homozygous for a de novo 473C > T mutation, causing the T158M amino acid change. Chromosome analysis showed a normal karyotype, and the hap- lotype analysis ruled out the possibility of parental disomy or microdeletion in MECP2 gene. Cultured fibroblast analysis reveals a mosaic for the mutation. This is a documented case of a homozygous female with RS. Ó 2007 Elsevier Masson SAS. All rights reserved. Keywords: Homozygosity; Rett syndrome; Somatic mosaicism 1. Introduction X-chromosomal dominantly inherited Rett syndrome (RS) is a neurodevelopmental and one of the most frequent genetic diseases in girls. Clinically, phenotype spectrum is broad, ranging from primary developmental delay with inability to sit or walk and catastrophic epilepsy and only minor neurological symptoms, preserved language and well-preserved hand function [1]. Since 1999 the molecular basis is known [2,3]. De novo mutations in the coding region * Corresponding author. Tel.: þ43 512 504 23600; fax: þ43 512 504 23484. E-mail address: daniela.skladal@i-med.ac.at (D. Karall). 1769-7212/$ - see front matter Ó 2007 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.ejmg.2007.07.001 Available online at www.sciencedirect.com European Journal of Medical Genetics 50 (2007) 465e468 http://www.elsevier.com/locate/ejmg + MODEL