title: Preparation and validation of the first WHO international genetic reference panel for Fragile X syndrome.
abstract: 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 RMs for Fragile X syndrome has been developed, which should be stable over many years and available to all diagnostic laboratories. Immortalized cell lines were produced by Epstein-Barr virus transformation of lymphocytes from consenting patients. Genomic DNA was extracted in bulk and RM 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.
authors.affiliation: National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Herts, UK.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Hawkins
authors.forename: Jennifer
authors.initials: J
authors.lastname: Boyle
authors.forename: Kathleen E
authors.initials: KE
authors.lastname: Wright
authors.forename: Rob
authors.initials: R
authors.lastname: Elles
authors.forename: Simon C
authors.initials: SC
authors.lastname: Ramsden
authors.forename: Anna
authors.initials: A
authors.lastname: O'Grady
authors.forename: Michael
authors.initials: M
authors.lastname: Sweeney
authors.forename: David E
authors.initials: DE
authors.lastname: Barton
authors.forename: Trent
authors.initials: T
authors.lastname: Burgess
authors.forename: Melanie
authors.initials: M
authors.lastname: Moore
authors.forename: Chris
authors.initials: C
authors.lastname: Burns
authors.forename: Glyn
authors.initials: G
authors.lastname: Stacey
authors.forename: Elaine
authors.initials: E
authors.lastname: Gray
authors.forename: Paul
authors.initials: P
authors.lastname: Metcalfe
authors.forename: J Ross
authors.initials: JR
authors.lastname: Hawkins
mesh_terms: D002461:Cell Line, Transformed; D004247:DNA / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D005260:Female; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics / Q000592:standards*; D005600:Fragile X Syndrome / Q000175:diagnosis / Q000235:genetics*; D005820:Genetic Testing / Q000592:standards*; D005838:Genotype; D004854:Herpesvirus 4, Human; D006801:Humans; D008214:Lymphocytes / Q000821:virology; D008297:Male; D009154:Mutation; D012015:Reference Standards; D014944:World Health Organization
chemical_list: D004247:DNA; D051860:Fragile X Messenger Ribonucleoprotein 1