Small genomic rearrangements involving FMR1 support the importance of its gene dosage for normal neurocognitive function

Neurogenetics. 2012 Nov;13(4):333-9. doi: 10.1007/s10048-012-0340-y. Epub 2012 Aug 14.


Fragile X syndrome, the most common form of X-linked intellectual disability, results from transcriptional silencing of the FMR1 gene. As of yet, the phenotypic consequences of the duplication of FMR1 have not been well characterized. In this report, we characterize the clinical features in two females with duplications involving only the FMR1 gene. In addition, we describe the phenotypes of two subjects with deletion of FMR1 and show that both loss and gain of FMR1 copy number can lead to overlapping neurodevelopmental phenotypes. Our report supports the notion that FMR1 gene dosage is important for normal neurocognitive function.

Publication types

  • Case Reports
  • Research Support, N.I.H., Extramural

MeSH terms

  • Base Sequence
  • Child
  • Child Behavior Disorders / genetics
  • Child, Preschool
  • Cognition Disorders / genetics*
  • Developmental Disabilities / genetics
  • Female
  • Fragile X Mental Retardation Protein / genetics*
  • Fragile X Syndrome / genetics
  • Gene Deletion
  • Gene Dosage*
  • Gene Rearrangement*
  • Humans
  • Language Development Disorders / genetics
  • Male
  • Oligonucleotide Array Sequence Analysis


  • FMR1 protein, human
  • Fragile X Mental Retardation Protein