Rett Syndrome (RTT) is an X-linked dominant neurodevelopmental disorder, wh
ich almost exclusively affects girls, with an estimated prevalence of one i
n 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 Re
tt girls, and screened the MECP2 coding region for mutations by denaturing
high-performance liquid chromatography (DHPLC) and subsequent direct sequen
cing. DHPLC is a recently developed method for mutation screening which ide
ntifies 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 mut
ations, eight of which were previously unreported, were found in 35 out of
50 Rett girls (70%). Seven recurrent mutations were characterized in a tota
l of 22 unrelated cases. Initial DHPLC screening allowed the identification
of 17 out of 19 different mutations (90%); after optimal conditions were e
stablished, this figure increased to 100%, with all recurrent MECP2 mutatio
ns generating a characteristic chromatographic profile. Detailed clinical d
ata were available for 27 out of 35 mutation carrying Rett girls. Milder di
sease was detectable in patients carrying nonsense mutation as compared to
patients carrying missense mutations, although this difference was not stat
istically significant (P = 0.077). Hum Mutat 18.132-140, 2001. (C) 2001 Wil
ey-Liss, Inc.