Preparation and validation of the first WHO international genetic reference panel for Fragile X syndrome

J. Ross Hawkins (1) , Malcolm Hawkins (1) , Jennifer Boyle (1) , Kathleen E Wright (1) , Rob Elles (1) , Simon C Ramsden (1) , Anna O'Grady (1) , Michael Sweeney (1) , David Edward Barton (1) , Trent Burgess (1) , Glyn Stacey (1) , Elaine Gray (1) , Paul Metcalfe (1) , Melanie Moore (1) , Chris Burns (1)

1 Cell Biology & Imaging

Fragile X syndrome is the most common inherited form of mental retardation. It is caused by expansion of a trinucleotide (CGG)n repeat sequence in the 5' untranslated region of the FMR1 gene, resulting in promoter hypermethylation and suppression of FMR1 transcription. Additionally, pre-mutation alleles in carrier males and females may result in Fragile X Tremor/Ataxia Syndrome and primary ovarian insufficiency respectively. Fragile X is one of the most commonly requested molecular genetic tests worldwide. Quality assessment schemes have identified a wide disparity in allele sizing between laboratories. It is therefore important that clinical laboratories have access to characterized reference materials (RMs) to aid accurate allele sizing and diagnosis. With this in mind, a panel of genotyping reference materials for Fragile X syndrome has been developed which should be stable over many years and available to all diagnostic laboratories. Immortalised cell lines were produced by Epstein-Barr virus transformation of lymphocytes from consenting patients. Genomic DNA was extracted in bulk and reference material aliquots were freeze-dried in glass ampoules. Twenty one laboratories from seventeen countries participated in a collaborative study to assess their suitability. Participants evaluated the samples (blinded, in triplicate) in their routine methods alongside in-house and commercial controls. The panel of five genomic DNA samples was endorsed by the European Society of Human Genetics and approved as an International Standard by the Expert Committee on Biological Standardization at the World Health Organization.

Mots clés: Fragile X syndrome; FMR1; certified reference materials

J. Ross Hawkins, Malcolm Hawkins, Jennifer Boyle, Kathleen E Wright, Rob Elles, et al.. Preparation and validation of the first WHO international genetic reference panel for Fragile X syndrome. European Journal of Human Genetics, 2010, ⟨10.1038/ejhg.2010.135⟩. ⟨hal-00569397⟩