Molecular genetic analysis of candidate genes for glutaric aciduria type II in a cohort of patients from Queensland, Australia.

Glutaric aciduria type II (GAII) is a heterogeneous genetic disorder affecting mitochondrial fatty acid, amino acid and choline oxidation. Clinical manifestations vary across the lifespan and onset may occur at any time from the early neonatal period to advanced adulthood. Historically, some patients, in particular those with late onset disease, have experienced significant benefit from riboflavin supplementation.

Feasibility of Targeted Next-Generation DNA Sequencing for Expanding Population Newborn Screening.

Background: Newborn screening (NBS) is an effective public health intervention that reduces death and disability from treatable genetic diseases, but many conditions are not screened due to a lack of a suitable assay. Whole genome and whole exome sequencing can potentially expand NBS but there remain many technical challenges preventing their use in population NBS. We investigated if targeted gene sequencing (TGS) is a feasible methodology for expanding NBS.

Comparison between free β subunit of human chorionic gonadotropin (hCG) and total hCG assays in adults with testicular cancer.

Objectives: We tested the hypothesis that the free-β subunit (βhCG) is diagnostically more sensitive with total hCG assays (hCGt) not detecting all tumours secreting βhCG. The effects of sex, age, and renal failure were investigated as secondary objectives.

Methods: We compared βhCG with hCGt in 204 testicular cancer patients (99 seminomas, 105 non-seminonatous germ cell tumours).

Technical feasibility of newborn screening for spinal muscular atrophy by next-generation DNA sequencing.

Newborn screening (NBS) assays for spinal muscular atrophy (SMA) typically use a polymerase chain reaction (PCR) based assay to identify individuals with homozygous deletion in exon 7 of the gene. Due to high DNA sequence homology between and , it has previously been difficult to accurately bioinformatically map short reads from next-generation DNA sequencing (NGS) to , resulting in low analytical performance and preventing NGS being used for SMA screening. Advances in bioinformatics have allowed NGS to be used in diagnostic settings, but to date these assays have not reached the scale required for high volume population newborn screening and have not been performed on the dried blood spot samples that NBS programs currently use.

The inequity of targeted cystic fibrosis reproductive carrier screening tests in Australia.

Objective: European and Australian guidelines for cystic fibrosis (CF) reproductive carrier screening recommend testing a small number of high frequency CF causing variants, rather than comprehensive CFTR sequencing. The study objective was to determine variant detection rates of commercially available targeted reproductive carrier screening tests in Australia.

Methods: Next-generation DNA sequencing of the CFTR gene was performed on 2552 individuals from a whole population sample to identify CF causing variants.

Evaluation of the Atellica TnIH cardiac troponin I assay and assessment of biological equivalence.

Objectives: We evaluated the analytical performance characteristics and the biological equivalence of the Atellica TnIH assay.

Methods: Precision, detection capability, linearity, and sex specific 99 percentiles were determined . Classification of patients relative to the 99 percentiles was used to assess biological equivalence.

How comparable are total human chorionic gonadotropin (hCGt) tumour markers assays?

Background Total human chorionic gonadotropin (hCGt) tumour marker testing is regarded as an "off label" application for most commercial methods. We compared four assays in patients with a hCGt tumour marker request. We hypothesised that regression slopes would be altered and that outliers would be more common with tumour marker than with pregnancy samples if the detection of malignancy associated hCG molecular forms differed amongst assays.

A critical evaluation of the Beckman Coulter Access hsTnI: Analytical performance, reference interval and concordance.

Introduction: We investigated the analytical performance, outlier rate, carryover and reference interval of the Beckman Coulter Access hsTnI in detail and compared it with historical and other commercial assays.

Materials And Methods: We compared the imprecision, detection capability, analytical sensitivity, outlier rate and carryover against two previous Access AccuTnI assay versions. We established the reference interval with stored samples from a previous study and compared the concordances and variances with the Access AccuTnI+3 as well as with two commercial assays.

Mind the gap: shortcomings of the osmotic gap and a possible solution.

Background Measured (MO) and calculated osmotic concentrations (CO) and the osmotic gap (OG) are commonly used in the investigation of electrolyte and volume disturbances as well as in cases of suspected volatile ingestion. Methods We compared 38 published formulae for CO with MO on a large data-set ( n = 9466) and adjusted the CO with the result of a Passing-Bablok regression procedure. Validation of this adjustment was performed with a separate data-set ( n = 2082).

Cardiac Troponin I carryover by very high patient samples still causes false-positive results on the Beckman Coulter AccuTnI + 3.

Background: False-positive cardiac troponin I results as a result of carryover have previously been reported on the Beckman Coulter AccuTnI assay. We sought to determine if the carryover problem had been resolved with the new AccuTnI + 3 assay.

Methods: Carryover experiments were performed in parallel on the Beckman Coulter Access2 analyser using the legacy AccuTnI and new AccuTnI + 3 assays.

ELF score ≥9.8 indicates advanced hepatic fibrosis and is influenced by age, steatosis and histological activity.

Background & Aims: There is increasing need to identify individuals with advanced liver fibrosis, who are at risk of complications such as hepatocellular carcinoma. The commercially available enhanced liver fibrosis (ELF) test provides a non-invasive assessment of fibrosis severity. This study was designed to determine the diagnostic accuracy of the manufacturer's cut-off value (≥9.

Hook effect in Abbott i-STAT β-human chorionic gonadotropin (β-hCG) point of care assay.

Unlabelled: Point-of-care testing for β-hCG has been widely advocated to allow rapid diagnosis/exclusion of pregnancy in the emergency department. A quantitative blood β-hCG assay has the additional benefit of being able to monitor the viability of pregnancy, using serial measurements, to determine the appropriate expected increase in β-hCG levels over time (e.g.

Combined light chain immunofixation to detect monoclonal gammopathy: a comparison to standard electrophoresis in serum and urine.

Background: The purpose of this study was to evaluate a combined κ and λ light chain immunofixation (CLIF) as a screening tool to detect monoclonal immunoglobulins in serum and urine. A secondary aim was to investigate the impact on workflow and reagent utilisation of a systematic implementation of CLIF in addition to routine protein electrophoresis (PE) on all samples.

Methods: Light chain antisera (κ and λ) were mixed in a 1:1 ratio and loaded in the same sequence as the PE to create a superimposable image.

Towards a consistent definition of a significant delta troponin with z-scores: a way out of chaos?

Aims: We assessed the diagnostic performance of z-scores to define a significant delta cardiac troponin (cTn) in a cohort of patients with well-defined clinical outcomes.

Methods: We calculated z-scores, which are dependent on the analytical precision and biological variation, to report changes in cTn. We compared the diagnostic performances of a relative delta (%Δ), actual delta (Δ), and z-scores in 762 emergency department patients with symptoms of suspected acute coronary syndrome.

Clinical utility of ADAMTS-13 testing in suspected thrombotic microangiopathy: an audit of ADAMTS-13 activity assay requests in routine practice from a tertiary hospital.

Aims: Differentiation between thrombotic thrombocytopenic purpura (TTP) and other microangiopathic haemolytic anaemia (MAHA) processes can be difficult. Since the documentation of ADAMTS-13 deficiency in TTP, several ADAMTS-13 activity assays have been developed for use in the diagnosis of TTP and/or other microangiopathic disorders. We reviewed the clinical utility of ADAMTS-13 activity testing in suspected TTP, as used in routine clinical practice in a tertiary referral hospital.

Investigation of cholesterol bias due to a matrix effect of external quality assurance samples: how true is your cholesterol method?

Background: Comparability of cholesterol measurement is clinically required and external quality assurance (EQA) programmes are important to verify the trueness of routine methods.

Methods: We developed a gas chromatography-isotope dilution mass spectrometry (GC-IDMS) total cholesterol assay to investigate the cause of a suspected matrix-related negative bias with the Beckman Coulter enzymatic method discovered in an EQA programme. The GC-IDMS method was calibrated with certified reference material and verified against a secondary reference method.

Serial cardiac troponin differences measured on four contemporary analyzers: relative differences, actual differences and reference change values compared.

Introduction: The diagnosis of myocardial infarction is in part predicated on a rise and/or fall in cardiac troponin (cTn). z-Values incorporate analytical and biological variation to standardize serial differences: z=Δ/√[2SD²(Analytical) + 2SD²(Biological)]. We investigated the theoretical distributions of actual differences (Δ), relative differences (%Δ) and z-values and compared the agreement in classification of differences measured on four contemporary platforms.

Evaluation of the N Latex FLC free light chain assay on the Siemens BN analyser: precision, agreement, linearity and variation between reagent lots.

Background: The clinical utility of serum κ and λ free light chains (FLC) for the diagnosis and prognosis of plasma cell proliferative disorders is well established. We assessed the analytical performance of the N Latex FLC assays and compared it with the Freelite™ assays.

Methods: Analytical precision was assessed according to the CLSI EP5-A2 protocol.

Probing indiscretions: contamination of cardiac troponin reagent by very high patient samples causes false-positive results.

Background: Cardiac troponin (cTn) has become the standard biomarker for the diagnosis of acute coronary syndromes. False-positive cTnI results have previously been reported on the Beckman Coulter analysers, which were shown to be random, not reproducible and occurred more commonly than expected. Our investigation ensued after a patient sample with an inordinately elevated cTnI was analysed, followed by a series of false-positive results being reported.