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).