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Open AccessArticle

Are We Ready for Fragile X Newborn Screening Testing?—Lessons Learnt from a Feasibility Study

The NSW Newborn Screening Programme, The Children’s Hospital at Westmead, Westmead, NSW 2145, Australia
Disciplines of Paediatrics & Child Health and Genetic Medicine, The University of Sydney, Sydney, NSW 2006, Australia
Sydney Genome Diagnostics—Department of Molecular Genetics, The Children’s Hospital at Westmead, Westmead, NSW 2145, Australia
Genetics of Learning Disability, Hunter Genetics, Waratah, NSW 2298, Australia
Author to whom correspondence should be addressed.
Int. J. Neonatal Screen. 2018, 4(1), 9;
Received: 17 November 2017 / Revised: 16 January 2018 / Accepted: 23 January 2018 / Published: 13 February 2018
Fragile X syndrome (FXS) is the most prevalent heritable cause of cognitive impairment but is not yet included in a newborn screening (NBS) program within Australia. This paper aims to assess the feasibility and reliability of population screening for FXS using a pilot study in one hospital. A total of 1971 mothers consented for 2000 newborns to be tested using routine NBS dried blood spot samples. DNA was extracted and a modified PCR assay with a chimeric CGG primer was used to detect fragile X alleles in both males and females in the normal, premutation, and full mutation ranges. A routine PCR-based fragile X assay was run in parallel to validate the chimeric primer assay. Babies with CGG repeat number ≥59 were referred for family studies. One thousand nine hundred and ninety NBS samples had a CGG repeat number less than 55 (1986 < 50); 10 had premutation alleles >54 CGG repeats (1/123 females and 1/507 males). There was complete concordance between the two PCR-based assays. A recent review revealed no clinically identified cases in the cohort up to 5 years later. The cost per test was $AUD19. Fragile X status can be determined on routine NBS samples using the chimeric primer assay. However, whilst this assay may not be considered cost-effective for population screening, it could be considered as a second-tier assay to a developed immunoassay for fragile X mental retardation protein (FMRP). View Full-Text
Keywords: newborn screening; fragile X syndrome newborn screening; fragile X syndrome
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Wotton, T.; Wiley, V.; Bennetts, B.; Christie, L.; Wilcken, B.; Jenkins, G.; Rogers, C.; Boyle, J.; Field, M. Are We Ready for Fragile X Newborn Screening Testing?—Lessons Learnt from a Feasibility Study. Int. J. Neonatal Screen. 2018, 4, 9.

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