Newborn Screening for Severe Combined Immunodeficiency: Do Preterm Infants Require Special Consideration?

The Wisconsin Newborn Screening (NBS) Program began screening for severe combined immunodeficiency (SCID) in 2008, using real-time PCR to quantitate T-cell receptor excision circles (TRECs) in DNA isolated from dried blood NBS specimens. Prompted by the observation that there were disproportionately more screening-positive cases in premature infants, we performed a study to assess whether there is a difference in TRECs between full-term and preterm newborns. Based on de-identified SCID data from 1 January to 30 June 2008, we evaluated the TRECs from 2510 preterm newborns (gestational age, 23-36 weeks) whose specimens were collected ≤72 h after birth. The TRECs from 5020 full-term newborns were included as controls. The relationship between TRECs and gestational age in weeks was estimated using linear regression analysis. The estimated increase in TRECs for every additional week of gestation is 9.60%. The 95% confidence interval is 8.95% to 10.25% (p ≤ 0.0001). Our data suggest that TRECs increase at a steady rate as gestational age increases. These results provide rationale for Wisconsin's existing premature infant screening procedure of recommending repeat NBS following an SCID screening positive in a premature infant instead of the flow cytometry confirmatory testing for SCID screening positives in full-term infants.

The Value of Cognitive Pretesting: Improving Validity and Revealing Blind Spots through the Development of a Newborn Screening Parent Experiences Survey.

Surveys are used to gather a range of data on newborn screening (NBS) processes. We describe the development of a survey about parents' NBS experiences, in the United States, informed by cognitive pretest interviews among parents with varying NBS test results (true-positive, false-positive, normal). Cognitive pretest interviews were conducted following a semi-structured script and notes were taken to identify problematic survey items. The study team met weekly to discuss pretest feedback, draft changes, and generate revised items. Pretests indicated that parent experiences with NBS are varied and NBS screening procedures are not well understood. Substantial modifications were made to survey questions concerning NBS testing and result communication. Pretesters often associated NBS with other tests/exams/scales-APGAR scores, Ages and Stages questionnaires, and genetic testing during pregnancy. Some pretesters recalled receiving NBS blood spot results during their hospital admission, an uncommon practice, and few recalled knowing results would be provided to them or their pediatrician in the first few weeks of life. Thorough explanations regarding NBS procedures and expectations were embedded within the survey to enhance and improve interpretation of survey questions. Future NBS experience surveys should utilize cognitive pretesting to capture divergent experiences and improve response validity.

Systems Integration: The Next Frontier in Newborn-Screening Timeliness.

CONTEXT: In 2015, the United States Federal Advisory Committee on Heritable Disorders in Newborns and Children issued recommendations for state-based newborn screening programs to benchmark improvements in newborn-screening timeliness. Newborn screening (NBS) timeliness encompasses the efficient collection, transportation, testing, and reporting of results. Nearly all state programs fail to achieve recommended timeliness benchmarks. OBJECTIVES: Our study explored the processes and procedures that accelerate or hamper progress toward improving NBS timeliness from a public health laboratory program perspective. DESIGN: We conducted semistructured interviews to elicit public health laboratory perspectives on NBS specimen delivery, laboratory testing and processing, communication of results to birthing providers, program staffing, and quality measures and data sharing. A content analysis explored practices, processes, and procedures related to NBS timeliness. A secondary analysis examined interorganizational strategies to enhance timeliness outcomes among NBS stakeholders. PARTICIPANTS: Ten laboratories participated in the study (n = 21 personnel). Participants included public health laboratory directors, NBS program managers, and NBS follow-up program staff. RESULTS: Efforts to improve NBS timeliness included engaging birthing providers, expanding courier services, extending operating hours, modifying staffing schedules, and implementing cross-training schedules to facilitate prompt collection, transport, and processing of NBS specimens. Sustained improvements will require implementing robust data systems, integrating laboratory and follow-up processes, and improving communication among all NBS stakeholders. Programs expressed a desire to refine timeliness metric definitions to ensure useful comparisons across states. CONCLUSIONS: Efforts to improve timeliness have accelerated in recent years; sustained progress will require increased coordination and integration among stakeholders in the NBS delivery system.

Misclassification of VLCAD carriers due to variable confirmatory testing after a positive NBS result.

The Iowa Newborn Screening (NBS) Program began screening for very long-chain acyl-CoA dehydrogenase deficiency (VLCAD) in 2003. Untreated VLCAD can lead to liver failure, heart failure, and death. Current confirmatory testing recommendations by the American College of Medical Genetics (ACMG) for VLCAD list molecular and functional analysis (i.e., fibroblast fatty acid oxidation probe) as optional. This can lead to misclassification of VLCAD carriers as false positives. Iowa implemented a comprehensive VLCAD confirmatory testing algorithm at the beginning of 2016 that included both molecular and fibroblast analysis. Here, we compare the historic multi-algorithmic confirmatory testing protocol (2005-2016) to this comprehensive protocol (2016-2017). A metabolic specialist reviewed all medical records and NBS data for each out-of-range VLCAD that fell in each testing period. During the comprehensive testing period, 48,651 specimens were screened. Thirteen individuals with out-of-range C14:1 results were classified as follows after review: ten carriers, zero true positives, zero false positives, zero lost to follow-up, and four unable to assess carrier status. During the variable testing period, a total of 486,566 specimens were screened. Eighty-five individuals with out-of-range C14:1 were classified as follows: 45 carriers, two true positives, four false positives, four lost to follow-up, and 30 unable to assess carrier status. Our findings suggest that many out-of-range VLCAD cases that do not receive molecular confirmatory testing could be carriers mistakenly classified as false positives. We recommend comprehensive molecular and functional testing for all children with out-of-range VLCAD NBS results.

Nuclear receptors and AMPK: can exercise mimetics cure diabetes?

Endurance exercise can lead to systemic improvements in insulin sensitivity and metabolic homeostasis, and is an effective approach to combat metabolic diseases. Pharmacological compounds that recapitulate the beneficial effects of exercise, also known as 'exercise mimetics', have the potential to improve disease symptoms of metabolic syndrome. These drugs, which can increase energy expenditure, suppress hepatic gluconeogenesis, and induce insulin sensitization, have accordingly been highly scrutinized for their utility in treating metabolic diseases including diabetes. Nevertheless, the identity of an efficacious exercise mimetic still remains elusive. In this review, we highlight several nuclear receptors and cofactors that are putative molecular targets for exercise mimetics, and review recent studies that provide advancements in our mechanistic understanding of how exercise mimetics exert their beneficial effects. We also discuss evidence from clinical trials using these compounds in human subjects to evaluate their efficacy in treating diabetes.

Improving newborn screening for cystic fibrosis using next-generation sequencing technology: a technical feasibility study.

PURPOSE: Many regions have implemented newborn screening (NBS) for cystic fibrosis (CF) using a limited panel of cystic fibrosis transmembrane regulator (CFTR) mutations after immunoreactive trypsinogen (IRT) analysis. We sought to assess the feasibility of further improving the screening using next-generation sequencing (NGS) technology. METHODS: An NGS assay was used to detect 162 CFTR mutations/variants characterized by the CFTR2 project. We used 67 dried blood spots (DBSs) containing 48 distinct CFTR mutations to validate the assay. NGS assay was retrospectively performed on 165 CF screen-positive samples with one CFTR mutation. RESULTS: The NGS assay was successfully performed using DNA isolated from DBSs, and it correctly detected all CFTR mutations in the validation. Among 165 screen-positive infants with one CFTR mutation, no additional disease-causing mutation was identified in 151 samples consistent with normal sweat tests. Five infants had a CF-causing mutation that was not included in this panel, and nine with two CF-causing mutations were identified. CONCLUSION: The NGS assay was 100% concordant with traditional methods. Retrospective analysis results indicate an IRT/NGS screening algorithm would enable high sensitivity, better specificity and positive predictive value (PPV). This study lays the foundation for prospective studies and for introducing NGS in NBS laboratories.

FMR1 CGG expansions: prevalence and sex ratios.

We have estimated the prevalence of FMR1 premutation and gray zone CGG repeat expansions in a population-based sample of 19,996 male and female adults in Wisconsin and compared the observed sex ratios of the prevalence of FMR1 CGG premutation and gray zone expansions to theoretical sex ratios. The female premutation prevalence was 1 in 148 and comparable to past research, but the male premutation prevalence of 1 in 290 is somewhat higher than most previous estimates. The female:male premutation prevalence ratio is in line with the theoretically predicted sex ratio. The prevalence of CGG repeats in the gray zone (45-54 repeats) was 1 in 33 females and 1 in 62 males. The prevalence of the "expanded" gray zone (defined here as 41-54 CGG repeats) was 1 in 14 females and 1 in 22 males, leading to a female:male ratio of 1.62 (95% confidence interval 1.39-1.90). This female:male ratio was significantly lower than the expected ratio of 2.0. We examined results from three previously published FMR1 prevalence studies and found similar female:male ratios for CGG repeats in this "expanded" gray zone range (pooled female:male ratio across all four studies 1.66, 95% confidence interval 1.51-1.82). Further research is needed to understand the apparent excess prevalence of males with CGG repeats in this range.

Characterization of a deep-coverage carrot (Daucus carota L.) BAC library and initial analysis of BAC-end sequences.

Carrot is the most economically important member of the Apiaceae family and a major source of provitamin A carotenoids in the human diet. However, carrot molecular resources are relatively underdeveloped, hampering a number of genetic studies. Here, we report on the synthesis and characterization of a bacterial artificial chromosome (BAC) library of carrot. The library is 17.3-fold redundant and consists of 92,160 clones with an average insert size of 121 kb. To provide an overview of the composition and organization of the carrot nuclear genome we generated and analyzed 2,696 BAC-end sequences (BES) from nearly 2,000 BACs, totaling 1.74 Mb of BES. This analysis revealed that 14% of the BES consists of known repetitive elements, with transposable elements representing more than 80% of this fraction. Eleven novel carrot repetitive elements were identified, covering 8.5% of the BES. Analysis of microsatellites showed a comparably low frequency for these elements in the carrot BES. Comparisons of the translated BES with protein databases indicated that approximately 10% of the carrot genome represents coding sequences. Moreover, among eight dicot species used for comparison purposes, carrot BES had highest homology to protein-coding sequences from tomato. This deep-coverage library will aid carrot breeding and genetics.