MEF2C haploinsufficiency caused by either microdeletion of the 5q14.3 region or mutation is responsible for severe mental retardation with stereotypic movements, epilepsy and/or cerebral malformations

J Med Genet. 2010 Jan;47(1):22-9. doi: 10.1136/jmg.2009.069732. Epub 2009 Jul 9.


Background: Over the last few years, array-comparative genomic hybridisation (CGH) has considerably improved our ability to detect cryptic unbalanced rearrangements in patients with syndromic mental retardation.

Method: Molecular karyotyping of six patients with syndromic mental retardation was carried out using whole-genome oligonucleotide array-CGH.

Results: 5q14.3 microdeletions ranging from 216 kb to 8.8 Mb were detected in five unrelated patients with the following phenotypic similarities: severe mental retardation with absent speech, hypotonia and stereotypic movements. Facial dysmorphic features, epilepsy and/or cerebral malformations were also present in most of these patients. The minimal common deleted region of these 5q14 microdeletions encompassed only MEF2C, the gene for a protein known to act in brain as a neurogenesis effector, which regulates excitatory synapse number. In a patient with a similar phenotype, an MEF2C nonsense mutation was subsequently identified.

Conclusion: Taken together, these results strongly suggest that haploinsufficiency of MEF2C is responsible for severe mental retardation with stereotypic movements, seizures and/or cerebral malformations.

Publication types

  • Case Reports

MeSH terms

  • Cerebrum / abnormalities*
  • Cerebrum / metabolism
  • Child
  • Child, Preschool
  • Chromosome Deletion*
  • Chromosomes, Human, Pair 5 / genetics*
  • Epilepsy / genetics*
  • Haploidy
  • Humans
  • Infant
  • Intellectual Disability / genetics*
  • MADS Domain Proteins / genetics*
  • MEF2 Transcription Factors
  • Myogenic Regulatory Factors / genetics*
  • Stereotypic Movement Disorder / genetics*


  • MADS Domain Proteins
  • MEF2 Transcription Factors
  • MEF2C protein, human
  • Myogenic Regulatory Factors