Mutations in MEF2C from the 5q14.3q15 microdeletion syndrome region are a frequent cause of severe mental retardation and diminish MECP2 and CDKL5 expression.
The etiology of mental retardation remains elusive in the majority of cases. Microdeletions within chromosomal bands 5q14.3q15 were recently identified as a recurrent cause of severe mental retardation, epilepsy, muscular hypotonia, and variable minor anomalies. By molecular karyotyping we identified two novel 2.4- and 1.5-Mb microdeletions of this region in patients with a similar phenotype. Both deletions contained the MEF2C gene, which is located proximally to the previously defined smallest region of overlap. Nevertheless, due to its known role in neurogenesis, we considered MEF2C as a phenocritical candidate gene for the 5q14.3q15 microdeletion phenotype. We therefore performed mutational analysis in 362 patients with severe mental retardation and found two truncating and two missense de novo mutations in MEF2C, establishing defects in this transcription factor as a novel relatively frequent autosomal dominant cause of severe mental retardation accounting for as much as 1.1% of patients. In these patients we found diminished MECP2 and CDKL5 expression in vivo, and transcriptional reporter assays indicated that MEF2C mutations diminish synergistic transactivation of E-box promoters including that of MECP2 and CDKL5. We therefore conclude that the phenotypic overlap of patients with MEF2C mutations and atypical Rett syndrome is due to the involvement of a common pathway.
Institute of Human Genetics, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany.
Markus
M
Zweier
Anne
A
Gregor
Christiane
C
Zweier
Hartmut
H
Engels
Heinrich
H
Sticht
Eva
E
Wohlleber
Emilia K
EK
Bijlsma
Susan E
SE
Holder
Martin
M
Zenker
Eva
E
Rossier
Ute
U
Grasshoff
Diana S
DS
Johnson
Lisa
L
Robertson
Helen V
HV
Firth
Arif B
AB
Ekici
André
A
Reis
Anita
A
Rauch
D000293:Adolescent; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D002872:Chromosome Deletion; D002895:Chromosomes, Human, Pair 5 / Q000235:genetics*; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004252:DNA Mutational Analysis; D005260:Female; D017353:Gene Deletion; D005786:Gene Expression Regulation; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics* / Q000473:pathology; D007621:Karyotyping; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D026161:MADS Domain Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D064326:MEF2 Transcription Factors; D008297:Male; D008958:Models, Molecular; D020125:Mutation, Missense; D018006:Myogenic Regulatory Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013577:Syndrome
D026161:MADS Domain Proteins; D064326:MEF2 Transcription Factors; C578040:MEF2C protein, human; D018006:Myogenic Regulatory Factors; D011993:Recombinant Fusion Proteins; D004247:DNA; D008156:Luciferases; D017346:Protein Serine-Threonine Kinases; C114482:CDKL5 protein, human