MeCP2 mutations in children with and without the phenotype of Rett syndrome.
BACKGROUND
Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the X-linked methyl CpG binding protein 2 (MeCP2) gene.


METHODS
One hundred sixteen patients with classical and atypical RTT were studied for mutations of the MeCP2 gene by using DHPLC and direct sequencing.


RESULTS
Causative mutations in the MeCP2 gene were identified in 63% of patients, representing a total of 30 different mutations. Mutations were identified in 72% of patients with classical RTT and one third of atypical cases studied (8 of 25). The authors found 17 novel mutations, including a complex gene rearrangement found in one individual involving two deletions and a duplication. The duplication was identical to a region within the 3' untranslated region (UTR), and represents the first report of involvement of the 3' UTR in RTT. The authors also report the identification of MeCP2 mutations in two males; a Klinefelter's male with classic RTT (T158M) and a hemizygous male infant with a Xq27-28 inversion and a novel 32 bp frameshift deletion [1154(del32)]. Studies examining the relationship between mutation type, X-inactivation status, and severity of clinical presentation found significant differences in clinical presentation between different types of mutations. Mutations in the amino-terminus were significantly correlated with a more severe clinical presentation compared with mutations closer to the carboxyl-terminus of MeCP2. Skewed X-inactivation patterns were found in two asymptomatic carriers of MeCP2 mutations and six girls diagnosed with either atypical or classical RTT.


CONCLUSIONS
This patient series confirms the high frequency of MeCP2gene mutations causative of RTT in females and provides data concerning the molecular basis for clinical variability (mutation type and position and X-inactivation patterns).
Hoffbuhr
K
K
Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC 20010, USA.
Devaney
J M
JM
LaFleur
B
B
Sirianni
N
N
Scacheri
C
C
Giron
J
J
Schuette
J
J
Innis
J
J
Marino
M
M
Philippart
M
M
Narayanan
V
V
Umansky
R
R
Kronn
D
D
Hoffman
E P
EP
Naidu
S
S
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002868:Chromosomal Proteins, Non-Histone; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics*; D004303:Dosage Compensation, Genetic; D005260:Female; D017353:Gene Deletion; D015321:Gene Rearrangement; D005838:Genotype; D006801:Humans; D008297:Male; D051783:Methyl-CpG-Binding Protein 2; D010641:Phenotype; D017354:Point Mutation; D012097:Repressor Proteins; D015518:Rett Syndrome / Q000235:genetics*; D012720:Severity of Illness Index
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C497392:MECP2 protein, human; D051783:Methyl-CpG-Binding Protein 2; D012097:Repressor Proteins