Preimplantation diagnosis for fragile X syndrome based on the detection of the non-expanded paternal and maternal CGG

Prenat Diagn. 1999 Dec;19(13):1223-30.


Fragile X syndrome is the most common monogenic cause of mental retardation in boys. It is always characterized clinically by moderate mental retardation and often by a long face with large everted ears and macro-orchidism. The causal mutation is an expansion of a CGG triplet repeat in a 5' exon of the FMR-1 gene in Xq27.3. We report here for the first time a method for preimplantation genetic diagnosis (PGD) for fragile X syndrome based on the amplification of the CGG triplet in the normal allele. Our candidate-patient population, as well as two clinical preimplantation genetic diagnosis (PGD) cycles which led to a pregnancy with an unaffected fetus, are presented in this paper.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Base Sequence
  • Blastomeres
  • Embryonic Development*
  • Female
  • Fragile X Mental Retardation Protein
  • Fragile X Syndrome / diagnosis*
  • Fragile X Syndrome / genetics*
  • Humans
  • Intellectual Disability / genetics
  • Male
  • Mutation*
  • Nerve Tissue Proteins / genetics*
  • Polymerase Chain Reaction
  • Pregnancy
  • Preimplantation Diagnosis*
  • RNA-Binding Proteins*
  • Repetitive Sequences, Nucleic Acid
  • Sperm Injections, Intracytoplasmic


  • FMR1 protein, human
  • Nerve Tissue Proteins
  • RNA-Binding Proteins
  • Fragile X Mental Retardation Protein