Volume 45, Issue 6 - Special Issue: Pediatric Laboratory Medicine; Issue Editor: Klaus P. Kohse

Most Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections in children are mild or asymptomatic. Severe Coronavirus Disease 2019 (COVID-19) in children is infrequent. An estimated 0.3–1.3% of children with SARS-CoV-2 infection were admitted to hospital, and of these 13–23% needed critical care. SARS-CoV-2 related deaths were very rare in children, estimated at 2 per million. The vast majority of admitted children had one of shortness of breath, fever, and cough, but atypical symptoms are more common in children. Cases of Multisystem Inflammatory Syndrome in Children (MIS-C) have been linked to SARS-CoV-2 infection. Cardinal symptoms include prolonged fever, clinical signs of inflammation, gastro-intestinal symptoms, and cardiac dysfunction. Twenty two to 80% of patients with MIS-C needed critical care; mortality of MIS-C is around 2%. Six to 24% of children with MIS-C had coronary artery dilatation or cardiac aneurysms. Equipoise still exists between first-line treatment with immunoglobulins and steroids. Outcomes for children with MIS-C are generally very good in those recognised early and started on appropriate treatment. Vaccination schemes for children are rapidly expanding, with the benefits of preventing severe COVID-19 disease and MIS-C and reducing community transmission outweighing the risks of adverse events of, amongst others, myocarditis temporally related to COVID-19 vaccination in children and young adults. The imposed social distancing measures reduced the overall number of children with acute illness or injury presenting to urgent and emergency care facilities worldwide. No clear signal was seen that large numbers of children had a delayed presentation to emergency care departments with a serious illness. The social distancing measures negatively impacted the mental health of children.

Objectives Most rare diseases are genetic diseases. Due to the diversity of rare diseases and the high likelihood of patients with rare diseases to be undiagnosed or misdiagnosed, it is not unusual that these patients undergo a long diagnostic odyssey before they receive a definitive diagnosis. This situation presents a clear need to set up a dedicated clinical service to end the diagnostic odyssey of patients with rare diseases. Methods Therefore, in 2014, we started an Undiagnosed Diseases Program in Hong Kong with the aim of ending the diagnostic odyssey of patients and families with rare diseases by clinical whole-exome sequencing (CWES), who have not received a definitive diagnosis after extensive investigation. Results In this program, we have shown that genetic diseases diagnosed by CWES were different from that using traditional approaches indicating that CWES is an essential tool to diagnose rare diseases and ending diagnostic odysseys. In addition, we identified several novel genes responsible for monogenic diseases. These include the TOP2B gene for autism spectrum disorder, the DTYMK gene for severe cerebral atrophy, the KIF13A gene for a new mosaic ectodermal syndrome associated with hypomelanosis of Ito, and the CDC25B gene for a new syndrome of cardiomyopathy and endocrinopathy. Conclusions With the incorporation of CWES in an Undiagnosed Diseases Program, we have ended diagnostic odysseys of patients with rare diseases in Hong Kong in the past 7 years. In this program, we have shown that CWES is an essential tool to end diagnostic odysseys. With the declining cost of next-generation sequencers and reagents, CWES set-ups are now affordable for clinical laboratories. Indeed, owing to the increasing availability of CWES and treatment modalities for rare diseases, precedence can be given to both common and rare medical conditions.

Objectives Next generation sequencing (NGS) technology has allowed cost-effective massive parallel DNA sequencing. To evaluate the utility of NGS for newborn screening (NBS) of inborn errors of metabolism (IEM), a custom panel was designed to target 87 disease-related genes. The pilot study was primarily proposed for second-tier testing under the NBSIEM program in Hong Kong. Methods The validation of the panel was performed with two reference genomes and an external quality assurance (EQA) sample. Sequencing libraries were synthesized with amplicon-based approach. The libraries were pooled, spiked-in with 2% PhiX DNA as technical control, for 16-plex sequencing runs. Sequenced reads were analyzed using a commercially available pipeline. Results The average target region coverage was 208× and the fraction of region with target depth ≥20× was 95.7%, with a sensitivity of 91.2%. There were 85 out of 87 genes with acceptable coverage, and EQA result was satisfactory. The turnaround time from DNA extraction to completion of variant calling and quality control (QC) procedures was 2.5 days. Conclusions The NGS approach with the amplicon-based panel has been validated for analytical performance and is suitable for second-tier NBSIEM test.

The neonatal microbiome offers a valuable model for studying the origins of human health and disease. As the field of metagenomics expands, we also increase our understanding of early life influences on its development. In this review we will describe common techniques used to define and measure the microbiome. We will review in utero influences, normal perinatal development, and known risk factors for abnormal neonatal microbiome development. Finally, we will summarize current evidence that links early life microbial impacts on the development of chronic inflammatory diseases, obesity, and atopy.

Objectives To review current literature on the role of endothelial dysfunction in coronavirus disease-2019 (COVID-19) infection in terms of pathophysiology, laboratory features and markers, clinical phenotype in adults and children, as well as long COVID-19. Content We conducted a thorough assessment of the literature and critically analyzed current data, mostly utilizing the PubMed and Medline search engines to find original studies published in the previous decade. Summary and Outlook Accumulating evidence suggests that endothelial dysfunction may be a common denominator of severe COVID-19 in adults and children, as well as long COVID-19, implicating mutual pathophysiological pathways. This narrative review summarizes the up-to-date knowledge of endothelial dysfunction caused by COVID-19, including novel aspects of long COVID-19 and pediatric disease. This knowledge is important in order not only to understand the multisystemic attack of COVID-19, but also to improve patient management and prognosis.

Objectives We established reference intervals for serum concentrations of hormones from healthy pediatric subjects and investigated their associations with gender, body mass index (BMI), puberty and oral contraceptives (oC). Methods We calculated reference intervals for the thyroid parameters thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), and calcitonin (Ct); the bone markers osteocalcin, procolagen type 1 N-propeptide, and carboxy-terminal cross-linking telopeptide of type 1 collagen; the calciotropic hormones 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone and the steroids cortisol, progesterone, 17-hydroxyprogesterone, androstenedione, testosterone, estradiol, dehydroepiandrosterone sulfate and aldosterone. Up to 10,002 blood serum samples from 3,229 healthy children and adolescents (age interval: 3 months to 20 years) were measured. To investigate the associations between the hormone levels with age, sex, weight status and the role of puberty-based changes, the measurement and BMI values were transformed into standard deviation scores. Results Most of the hormones depended on age- and gender. Puberty was linked to a, in part, temporary decrease in TSH, FT3 (for females), FT4, Ct, cortisol (for girls) and aldosterone (for boys) and peak in the bone marker and calciotropic hormones (excluding 25(OH)D) and nearly all remaining steroids. BMI had effects on the thyroid, bone, and calciotropic parameters, whereas oC led to increased cortisol, suppressed progesterone and estradiol values. Conclusions Age- and gender-specific reference intervals are essential for the interpretation of pediatric patients’ hormone measurements. Influencing factors as puberty, BMI, or oC should be taken into consideration for diagnosis and treatment monitoring.

Laboratory tests are essential to assess the health status and to guide patient care in individuals of all ages. The interpretation of quantitative test results requires availability of appropriate reference intervals, and reference intervals in children have to account for the extensive physiological dynamics with age in many biomarkers. Creation of reference intervals using conventional approaches requires the sampling of healthy individuals, which is opposed by ethical and practical considerations in children, due to the need for a large number of blood samples from healthy children of all ages, including neonates and young infants. This limits the availability and quality of pediatric reference intervals, and ultimately negatively impacts pediatric clinical decision-making. Data mining approaches use laboratory test results and clinical information from hospital information systems to create reference intervals. The extensive number of available test results from laboratory information systems and advanced statistical methods enable the creation of pediatric reference intervals with an unprecedented age-related accuracy for children of all ages. Ongoing developments regarding the availability and standardization of electronic medical records and of indirect statistical methods will further improve the benefit of data mining for pediatric reference intervals.

Electronic tools in clinical laboratory diagnostics can assist laboratory professionals, clinicians, and patients in medical diagnostic management and laboratory test interpretation. With increasing implementation of electronic health records (EHRs) and laboratory information systems worldwide, there is increasing demand for well-designed and evidence-based electronic resources. Both complex data-driven and simple interpretative electronic healthcare tools are currently available to improve the integration of clinical and laboratory information towards a more patient-centered approach to medicine. Several studies have reported positive clinical impact of electronic healthcare tool implementation in clinical laboratory diagnostics, including in the management of neonatal bilirubinemia, cardiac disease, and nutritional status. As patients have increasing access to their medical laboratory data, it is essential that accessible electronic healthcare tools are evidence-based and user-friendly for individuals of varying digital and medical literacy. Indeed, studies suggest electronic healthcare tool development processes significantly lack the involvement of relevant healthcare professionals and often present misinformation, including erroneous calculation algorithms or inappropriate interpretative recommendations. The current review provides an overview of the utility of available electronic healthcare tools in clinical laboratory diagnostics and critically reviews potential limitations and benefits of their clinical implementation. The Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) online database is also detailed as an example of a pediatric diagnostic tool with widespread global impact.