Preparation and validation of the first WHO international genetic reference panel for Fragile X syndrome.
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.
Hawkins
Malcolm
M
National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Herts, UK.
Boyle
Jennifer
J
Wright
Kathleen E
KE
Elles
Rob
R
Ramsden
Simon C
SC
O'Grady
Anna
A
Sweeney
Michael
M
Barton
David E
DE
Burgess
Trent
T
Moore
Melanie
M
Burns
Chris
C
Stacey
Glyn
G
Gray
Elaine
E
Metcalfe
Paul
P
Hawkins
J Ross
JR
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
D004247:DNA; D051860:Fragile X Messenger Ribonucleoprotein 1