Liquid Chromatography-Tandem Mass Spectrometry Assay of Leukocyte Acid α-Glucosidase for Post-Newborn Screening Evaluation of Pompe Disease.

BACKGROUND: Pompe disease (PD) is the first lysosomal storage disorder to be added to the Recommended Uniform Screening Panel for newborn screening. This condition has a broad phenotypic spectrum, ranging from an infantile form (IOPD), with severe morbidity and mortality in infancy, to a late-onset form (LOPD) with variable onset and progressive weakness and respiratory failure. Because the prognosis and treatment options are different for IOPD and LOPD, it is important to accurately determine an individual's phenotype. To date, no enzyme assay of acid α-glucosidase (GAA) has been described that can differentiate IOPD vs LOPD using blood samples. METHODS: We incubated 10 µL leukocyte lysate and 25 µL GAA substrate and internal standard (IS) assay cocktail for 1 h. The reaction was purified by a liquid-liquid extraction. The extracts were evaporated and reconstituted in 200 µL methanol and analyzed by LC-MS/MS for GAA activity. RESULTS: A 700-fold higher analytical range was observed with the LC-MS/MS assay compared to the fluorometric method. When GAA-null and GAA-containing fibroblast lysates were mixed, GAA activity could be measured accurately even in the range of 0%-1% of normal. The leukocyte GAA activity in IOPD (n = 4) and LOPD (n = 19) was 0.44-1.75 nmol · h-1 · mg-1 and 2.0-6.5 nmol · h-1 · mg-1, respectively, with no overlap. The GAA activity of pseudodeficiency patients ranged from 3.0-28.1 nmol · h-1 · mg-1, showing substantial but incomplete separation from the LOPD group. CONCLUSIONS: This assay allows determination of low residual GAA activity in leukocytes. IOPD, LOPD, and pseudodeficiency patients can be partially differentiated by measuring GAA using blood samples.

Clinical Sensitivity of Cystic Fibrosis Mutation Panels in a Diverse Population.

Infants are screened for cystic fibrosis (CF) in New York State (NYS) using an IRT-DNA algorithm. The purpose of this study was to validate and assess clinical validity of the US FDA-cleared Illumina MiSeqDx CF 139-Variant Assay (139-VA) in the diverse NYS CF population. The study included 439 infants with CF identified via newborn screening (NBS) from 2002 to 2012. All had been screened using the Abbott Molecular CF Genotyping Assay or the Hologic InPlex CF Molecular Test. All with CF and zero or one mutation were tested using the 139-VA. DNA extracted from dried blood spots was reliably and accurately genotyped using the 139-VA. Sixty-three additional mutations were identified. Clinical sensitivity of three panels ranged from 76.2% (23 mutations recommended for screening by ACMG/ACOG) to 79.7% (current NYS 39-mutation InPlex panel), up to 86.0% for the 139-VA. For all, sensitivity was highest in Whites and lowest in the Black population. Although the sample size was small, there was a nearly 20% increase in sensitivity for the Black CF population using the 139-VA (68.2%) over the ACMG/ACOG and InPlex panels (both 50.0%). Overall, the 139-VA is more sensitive than other commercially available panels, and could be considered for NBS, clinical, or research laboratories conducting CF screening.

Validation of a Custom Next-Generation Sequencing Assay for Cystic Fibrosis Newborn Screening.

Newborn screening (NBS) for Cystic Fibrosis (CF) is associated with improved outcomes. All US states screen for CF; however, CF NBS algorithms have high false positive (FP) rates. In New York State (NYS), the positive predictive value of CF NBS improved from 3.7% to 25.2% following the implementation of a three-tier IRT-DNA-SEQ approach using commercially available tests. Here we describe a modification of the NYS CF NBS algorithm via transition to a new custom next-generation sequencing (NGS) platform for more comprehensive cystic fibrosis transmembrane conductance regulator (CFTR) gene analysis. After full gene sequencing, a tiered strategy is used to first analyze only a specific panel of 338 clinically relevant CFTR variants (second-tier), followed by unblinding of all sequence variants and bioinformatic assessment of deletions/duplications in a subset of samples requiring third-tier analysis. We demonstrate the analytical and clinical validity of the assay and the feasibility of use in the NBS setting. The custom assay has streamlined our molecular workflow, increased throughput, and allows for bioinformatic customization of second-tier variant panel content. NBS aims to identify those infants with the highest disease risk. Technological molecular improvements can be applied to NBS algorithms to reduce the burden of FP referrals without loss of sensitivity.

Children computer mouse use and anthropometry.

Studies have shown that increased computer use among adults in occupational settings is associated with the development of cumulative trauma disorders; however, the need to address how adult-sized mice and keyboards are affecting children is becoming increasingly important as both access to and use of computers is increasing among today's youth. To address the potential mismatch that exists between child stature and computer input device size and activation force, we have applied existing, age-specific, anthropometric data to elements of device design, including mouse size (length, width, height, switch location), and mouse-button activation forces. Trends supported the development of smaller computer input devices with lower activation forces for smaller statured individuals including children. Distinct and consistent trends in size delineations were seen across gender and age groups-trends that correlate well with grades and schooling in the United States education system . Three to four mouse sizes would be recommended: a mouse sized for adult and high school males; one for adult and high school females and junior high males; one for elementary school children, aged 6 to 10 years; and possibly a mouse for the smallest users who are less than six years old.

Construct validity of the relationship profile test: impact of gender, gender role, and gender role stereotype.

Research supports the construct validity of the Relationship Profile Test (RPT; Bornstein & Languirand, 2003), a 30-item, self-report measure of destructive overdependence (DO), dysfunctional detachment (DD), and healthy dependency. In this investigation, we assessed the relationships of gender, gender role, and gender role stereotype ratings to RPT subscale scores. In Study 1, we replicated earlier patterns of gender differences in RPT scores, assessed cross-sample consistency in gender difference effect sizes, and provided preliminary nonclinical norms for the RPT subscales. Study 2 showed that--as expected--DO items are perceived as stereotypically feminine, whereas DD items are perceived as stereotypically masculine. In Study 3, we examined the relationships of RPT subscale scores to masculinity, femininity, and androgyny scores. We discuss the theoretical, empirical, and clinical implications of these findings.