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Purpose: The purpose of this study was to compare performance metrics of postanalytical interpretive tools of the Region 4 Stork collaborative project to the actual outcome based on cutoff values for amino acids and acylcarnitines selected by the California newborn screening program., Methods: This study was a retrospective review of the outcome of 176,186 subjects born in California between 1 January and 30 June 2012. Raw data were uploaded to the Region 4 Stork Web portal as .csv files to calculate tool scores for 48 conditions simultaneously using a previously unpublished functionality, the tool runner. Scores for individual target conditions were deemed informative when equal or greater to the value representing the first percentile rank of known true-positive cases (17,099 cases in total)., Results: In the study period, the actual false-positive rate and positive predictive value were 0.26 and 10%, respectively. Utilization of the Region 4 Stork tools, simple interpretation rules, and second-tier tests could have achieved a false-positive rate as low as 0.02% and a positive predictive value >50% by replacing the cutoff system with Region 4 Stork tools as the primary method for postanalytical interpretation., Conclusion: Region 4 Stork interpretive tools, second-tier tests, and other evidence-based interpretation rules could have reduced false-positive cases by up to 90% in California.

Purpose: To improve quality of newborn screening by tandem mass spectrometry with a novel approach made possible by the collaboration of 154 laboratories in 49 countries., Methods: A database of 767,464 results from 12,721 cases affected with 60 conditions was used to build multivariate pattern recognition software that generates tools integrating multiple clinically significant results into a single score. This score is determined by the overlap between normal and disease ranges, penetration within the disease range, differences between conditions, and weighted correction factors., Results: Ninety tools target either a single condition or the differential diagnosis between multiple conditions. Scores are expressed as the percentile rank among all cases with the same condition and are compared to interpretation guidelines. Retrospective evaluation of past cases suggests that these tools could have avoided at least half of 279 false-positive outcomes caused by carrier status for fatty-acid oxidation disorders and could have prevented 88% of known false-negative events., Conclusion: Application of this computational approach to raw data is independent from single analyte cutoff values. In Minnesota, the tools have been a major contributing factor to the sustained achievement of a false-positive rate below 0.1% and a positive predictive value above 60%.

In this study we examine some of the phenotypic and functional characteristics that accompany the differentiation of monocyte-macrophages from nonadherent precursors present in cord blood. Class II major histocompatibility complex (MHC) molecules identified by monoclonal antibody (mAb) L243 were the earliest monocyte-macrophage-associated antigens to be expressed. CD14 molecules, identified by mAb MO.2, and the transferrin receptor, identified by mAb OKT9, increased linearly over the 21-day culture period. In contrast, Fc gamma R were not expressed on these cells until 14 days of culture. Fc gamma RI was present on approximately 80% of the cells, whereas Fc gamma RII and Fc gamma RIII were present on 30% and 20% of the cells, respectively. Functional activity of the nonadherent cell-derived monocyte-macrophages paralleled the phenotypic maturation of these cells. The capacity to stimulate a mixed leukocyte reaction paralleled the expression of class II MHC molecules. Similarly, the capacity to phagocytose Escherichia coli and Staphylococcus aureus paralleled the appearance of CR3. Indeed, phagocytosis of these organisms was partially blocked by mAb OKM-1. These studies demonstrate that monocyte-macrophages derived from cord blood nonadherent mononuclear cells are a useful population with which to characterize human macrophage differentiation and functional and phenotypic heterogeneity.