Fragile X Syndrome The Journal of Molecular Diagnostics Justine I. Lyons, Gregory R. Kerr, Patricia W. Mueller  The Journal of Molecular Diagnostics  Volume 17, Issue 5, Pages 463-471 (September 2015) DOI: 10.1016/j.jmoldx.2015.04.006 Copyright © 2015 Terms and Conditions

Figure 1 Expansion of the CGG repeats in the 5′ untranslated region of the FMR1 gene on the X chromosome can result in decreased mRNA and FMRP production, causing fragile X. FMRP, FMR1 protein. The Journal of Molecular Diagnostics 2015 17, 463-471DOI: (10.1016/j.jmoldx.2015.04.006) Copyright © 2015 Terms and Conditions

Figure 2 Tassone fragile X screening method29: A: The first step uses sequence-based forward and reverse PCR primers to amplify the CGG repeat region fragments which are analyzed on an ABI 3730 capillary electrophoresis DNA analyzer. B: If there are less than two peaks for females or no peak for males, the forward primer is run with a CGG-targeted reverse primer with capillary electrophoresis analysis of the resulting fragments. The Journal of Molecular Diagnostics 2015 17, 463-471DOI: (10.1016/j.jmoldx.2015.04.006) Copyright © 2015 Terms and Conditions

Figure 3 The Orpana fragile X screening method29 uses multiple heat pulses in the PCR extension step to destabilize secondary structures and to enhance the extension over the GC-rich sequence of the CGG repeat region. The method uses agarose gel electrophoresis to detect the resulting amplicons. The Journal of Molecular Diagnostics 2015 17, 463-471DOI: (10.1016/j.jmoldx.2015.04.006) Copyright © 2015 Terms and Conditions

Figure 4 The Teo fragile X screening method31 uses a melting curve analysis of triplet-primed PCR products in the 5′ and 3′ directions. The repeat-annealing primers tail-CCGR and tail-CGGF anneal fully within the repeat sequence and are tailed at their 5′ ends with noncomplementary sequences to enhance the production of amplicons. The Journal of Molecular Diagnostics 2015 17, 463-471DOI: (10.1016/j.jmoldx.2015.04.006) Copyright © 2015 Terms and Conditions

Figure 5 Tassone method.29 A: A normal sample from a heterozygous female and a normal sample from a male analyzed with sequence-based forward and reverse primers. B: Samples from a female and male with a gray zone allele analyzed with sequence-based forward and reverse primers. C: A sample from a female with a normal 29 CGG-repeat allele and an expanded allele, and a sample from a male with an expanded CGG-repeat allele analyzed with sequence-based forward and reverse primers. D: Samples from a homozygous female with two normal 30 CGG-repeat alleles, a sample from a female with a normal and an expanded CGG allele, and a sample from a male with an expanded CGG allele run with a sequence-based primer and a chimeric CGG-targeted primer. The Journal of Molecular Diagnostics 2015 17, 463-471DOI: (10.1016/j.jmoldx.2015.04.006) Copyright © 2015 Terms and Conditions

Figure 6 Orpana method.30 Agarose gels of amplicons generated by heat-pulse PCR from males (A) and females (B). The allele sizes are indicated above the tracks. The Journal of Molecular Diagnostics 2015 17, 463-471DOI: (10.1016/j.jmoldx.2015.04.006) Copyright © 2015 Terms and Conditions

Figure 7 Teo method.31 Melting curves from a normal sample from a female with 18 and 29 CGG repeats (A) and a full mutation sample from a female with 21 and 650 CGG repeats (B). The vertical reference lines represent cutoffs of 83.3°C for the 5′ assay and 91°C for the 3′ assay. The Journal of Molecular Diagnostics 2015 17, 463-471DOI: (10.1016/j.jmoldx.2015.04.006) Copyright © 2015 Terms and Conditions

Figure 8 Teo method.31 The sensitivity and specificity of the 3′ and 5′ assay at different temperature cutoffs. The Journal of Molecular Diagnostics 2015 17, 463-471DOI: (10.1016/j.jmoldx.2015.04.006) Copyright © 2015 Terms and Conditions