Search

We report a direct DNA sequencing analysis of the MECP2 gene undertaken on a further 64 Italian patients with Rett syndrome by using a LICOR 4200 Automated Sequencer. All of the girls entering the study had a consistent clinical diagnosis for this disorder. All coding regions and the flanking intronic splice site sequences were amplified as three non-overlapping fragments by using both forward and reverse primers. The results were then compared to the MECP2 reference sequences published in GenBank. Mutations of the MECP2 gene were identified in 64 of 75 (85.33%) unrelated sporadic Rett syndrome girls. Genotype/phenotype correlation studies, in particular in groups of patients with the same mutation, did not offer definitive and interesting data.

Rett Syndrome (RTT) is an X-linked dominant neurodevelopmental disorder, which almost exclusively affects girls, with an estimated prevalence of one in 10,000-15,000 female births. Mutations in the methyl CpG binding protein 2 gene (MECP2) have been identified in roughly 75% of classical Rett girls. The vast majority of Rett cases (99%) are sporadic in origin, and are due to de novo mutations. We collected DNA samples from 50 Italian classical Rett girls, and screened the MECP2 coding region for mutations by denaturing high-performance liquid chromatography (DHPLC) and subsequent direct sequencing. DHPLC is a recently developed method for mutation screening which identifies heteroduplexes formed in DNA samples containing mismatches between wild type and mutant DNA strands, combining high sensitivity, reduced cost per run, and high throughput. In our series, 19 different de novo MECP2 mutations, eight of which were previously unreported, were found in 35 out of 50 Rett girls (70%). Seven recurrent mutations were characterized in a total of 22 unrelated cases. Initial DHPLC screening allowed the identification of 17 out of 19 different mutations (90%); after optimal conditions were established, this figure increased to 100%, with all recurrent MECP2 mutations generating a characteristic chromatographic profile. Detailed clinical data were available for 27 out of 35 mutation carrying Rett girls. Milder disease was detectable in patients carrying nonsense mutation as compared to patients carrying missense mutations, although this difference was not statistically significant (P = 0.077)., (Copyright 2001 Wiley-Liss, Inc.)