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  Introduction : Rett syndrome is an X linked dominant neurological disorder that affects almost exclusively girls with an estimated prevalence of 10,000---20,000.Aim of the work : to highlight the clinical manifestations of Rett syndrome & to present genotype phenotype correlations.Materials & methods : the study included 15 girls ( 9 months- 5years) with typical Rett syndrome according to the international criteria .They were subjected to screening of the whole coding region of the MECP2gene (MECP2A& MECP2B) by DHPLC. Results: Microcephaly was present in  73.3%,stereotypic hand movement in100%.Recurrent seizures in 53.3%.Delayed language development  in 46.6% deterioration of speech in 53.3%,autistic features in 60%,growth retardation in 46.6%.Three mutations were detected in(66.6%): heterozygous for p.R270X mutation ( 3 cases) ,heterozygous for p.R255X mutation (3 cases)and heterozygous p.R168X nonsense mutation (4 cases .Phenotype genotype correlation between the group of mutated gene and those with no mutation showed that microcephaly was present in (80% versus 60% respectively),seizures (70% versus 20%), growth retardation (50% versus 40%) and autistic features (70% versus 40%).But for those with no mutation,they were more frequently able to walk (60% versus 40% with mutation ).

Conclusion: Mutations of MECP2 analysis were detected in 66.6% of Rett syndrome cases .Cases with detected mutation had more frequent seizures , microcephaly, growth retardation  and autism.Concerning cases with no mutation, further investigations are required for X linked candidate genes.