BackgroundPopulation screening for FMR1 mutations has been a topic of considerable discussion since the FMR1 gene was identified in 1991. Advances in understanding the molecular basis of fragile X syndrome (FXS) and in genetic testing methods have led to new, less expensive methodology to use for large screening endeavors. A core criterion for newborn screening is an accurate understanding of the public health burden of a disease, considering both disease severity and prevalence rate. This article addresses this need by reporting prevalence rates observed in a pilot newborn screening study for FXS in the US.MethodsBlood spot screening of 14,207 newborns (7,312 males and 6,895 females) was conducted in three birthing hospitals across the United States beginning in November 2008, using a PCR-based approach.ResultsThe prevalence of gray zone alleles was 1:66 females and 1:112 males, while the prevalence of a premutation was 1:209 females and 1:430 males. Differences in prevalence rates were observed among the various ethnic groups; specifically higher frequency for gray zone alleles in males was observed in the White group compared to the Hispanic and African-American groups. One full mutation male was identified (>200 CGG repeats).ConclusionsThe presented pilot study shows that newborn screening in fragile X is technically feasible and provides overall prevalence of the premutation and gray zone alleles in the USA, suggesting that the prevalence of the premutation, particularly in males, is higher than has been previously reported.

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Background Greater than 200 CGG repeats in the 5′UTR of the FMR1 gene leads to epigenetic silencing and lack of the FMR1 protein, causing Fragile X Syndrome. Individuals carriers of a premutation (PM) allele with 55–200 CGG repeats are typically unmethylated and can present with clinical features defined as FMR1 associated conditions. Methods Blood samples from 17 male PM carriers were assessed clinically and molecularly by Southern Blot, Western Blot, PCR and QRT-PCR. Blood and brain tissue from additional 18 PM males were also similarly examined. Continuous outcomes were modeled using linear regression and binary outcomes were modeled using logistic regression. Results Methylated alleles were detected in different fractions of blood cells in all PM cases (n= 17). CGG repeat numbers correlated with percent of methylation and mRNA levels and, especially in the upper PM range, with greater number of clinical involvements. Inter/intra- tissue somatic instability and differences in percent methylation were observed between blood and fibroblasts (n=4) and also observed between blood and different brain regions in three of the 18 premutation cases examined. CGG repeat lengths in lymphocytes remained unchanged over a period of time ranging from 2–6 years, three cases for whom multiple samples were available. Conclusion In addition to CGG size instability, individuals with a PM expanded alleles can exhibit methylation and display more clinical features likely due to RNA toxicity and/or FMR1 silencing. The observed association between CGG repeat length and percent of methylation with the severity of the clinical phenotypes underscores the potential value of methylation in affected PM to further understand penetrance, inform diagnosis and to expand treatment options.

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We systematically develop Bridgeland's [Bri1] and Bridgeland-Maciocia's [BriM] techniques for studying elliptic fibrations, and identify criteria that ensure 2-term complexes are mapped to torsion-free sheaves under a Fourier-Mukai transform. As an application, we construct an open immersion from a moduli of stable complexes to a moduli of Gieseker stable sheaves on elliptic threefolds. As another application, we give various 1-1 correspondences between fiberwise semistable torsion-free sheaves and codimension-1 sheaves on Weierstrass surfaces.

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