Int. J. Neonatal Screen., Volume 5, Issue 2 (June 2019) – 8 articles

The increasing availability of treatments and the importance of early intervention have stimulated interest in newborn screening for lysosomal storage diseases. Since 2015, 112,446 newborns in North Eastern Italy have been screened for four lysosomal disorders—mucopolysaccharidosis type I and Pompe, Fabry and Gaucher diseases—using a multiplexed tandem mass spectrometry (MS/MS) assay system. We recalled 138 neonates (0.12%) for collection of a second dried blood spot. Low activity was confirmed in 62 (0.06%), who underwent confirmatory testing. Twenty-five neonates (0.02%) were true positive: eight with Pompe disease; seven with Gaucher disease; eight with Fabry disease; and two with Mucopolysaccharidosis type I. The combined incidence of the four disorders was 1 in 4497 births. Except for Pompe disease, a second-tier test was implemented. We conclude that newborn screening for multiple lysosomal storage diseases combined with a second-tier test can largely eliminate false-positives and achieve rapid diagnosis. Full article

Genetic results of uncertain clinical significance are being returned to parents following newborn screening, representing a paradigm change in how society considers health and illness. ‘Cystic Fibrosis screen positive, inconclusive diagnosis’ (CFSPID) is a designation given to newborns with a positive screening result for, but not a definitive diagnosis of, cystic fibrosis. We explored the psychological impact of receiving a CFSPID result on parents. Five semi-structured interviews were conducted with eight parents whose children have CFSPID. Interpretative phenomenological analysis identified these themes: “The way we were told”: ‘diagnosis as a traumatic event’ focused on how parents were distressed and dissatisfied by the initial screening result communication, ‘Facing and challenging traditional ideas about health and illness’ explored the emerging problem of how CFSPID does not fit the commonly accepted medical model, and ‘Making certainty out of uncertainty’ explored the varying strategies parents developed to adapt to the uncertainty regarding their child’s prognosis. Findings suggest that CFSPID results caused parents’ distress, initiated with the first communication of the result and persisting thereafter. Our data suggests approaches to the delivery of CFSPID results that may reduce the impact. Work is needed to close the gap between healthcare advances and societies commonly held medical model. Full article

Newborn screening is a process-based public health service. Newborn screening staff and families alike are essential to maintaining the timeliness of the screening process. Newborn screening education must be accurate and accessible. Past newborn screening conferences have highlighted gaps in best practice and evidence-based guidance on newborn screening education. Sharing successful strategies across programs mitigates the scarcity of resources by cutting costs and reducing the burden of work. These factors illustrate the need for an education framework to guide newborn screening education efforts. The Newborn Screening Education Best Practices Framework responds to these issues by outlining guidance for newborn screening education approaches. Experts in the fields of newborn screening, genetics, and bioethics as well as previous research on best practice guidelines have contributed to the development of this framework. The framework outlines a process for users to evaluate newborn screening education approaches as best practices. This framework reviews best practices using a two-step approach, looking at guiding questions, implementation of the newborn screening issue, and evaluation. The framework helps the user define the characteristics of the newborn screening issue, intended audience, and practical steps to implementation, and then decide whether or not it can be used as a best practice. Full article

Spinal muscular atrophy (SMA) is one of the leading genetic causes of infant mortality with an incidence of 1:10,000. The recently-introduced antisense oligonucleotide treatment improves the outcome of this disease, in particular when applied at an early stage of progression. The genetic cause of SMA is, in >95% of cases, a homozygous deletion of the survival motor neuron 1 (SMN1) gene, which makes the low-cost detection of SMA cases as part of newborn screening programs feasible. We developed and validated a new SALSA MC002 melting curve assay that detects the absence of the SMN1 exon 7 DNA sequence without detecting asymptomatic carriers and reliably discriminates SMN1 from its genetic homolog SMN2 using crude extracts from newborn screening cards. Melting curve analysis shows peaks specific for both the SMN1 gene and the disease modifying SMN2 homolog. The detection of the SMN2 homolog, of which the only clinically relevant difference from the SMN1 gene is a single nucleotide in exon 7, was only used to confirm a correct reaction in samples that lacked the SMN1 gene, and not for SMN2 quantification. We retrieved 47 DBS samples from children with genetically-confirmed SMA, after informed consent from parents, and 375 controls from the national archive of the Dutch National Institute for Public Health and the Environment (RIVM). The assay correctly identified all anonymized and randomized SMA and control samples (i.e., sensitivity and specificity of 100%), without the detection of carriers, on the three most commonly-used PCR platforms with melting curve analysis. This test’s concordance with the second-tier ‘golden standard’ P021 SMA MLPA test was 100%. Using the new P021–B1 version, crude extracts from DBS cards could also be used to determine the SMN2 copy number of SMA patients with a high level of accuracy. The MC002 test showed the feasibility and accuracy of SMA screening in a neonatal screening program. Full article

Sickle cell disease (SCD) is a monogenetic disorder due to a single base-pair point mutation in the β-globin gene resulting in the substitution of the amino acid valine for glutamic acid in the β-globin chain. Phenotypic variation in the clinical presentation and disease outcome is a characteristic feature of the disorder. Understanding the pathogenesis and pathophysiology of the disorder is central to the choice of therapeutic development and intervention. In this special edition for newborn screening for haemoglobin disorders, it is pertinent to describe the genetic, pathologic and clinical presentation of sickle cell disease as a prelude to the justification for screening. Through a systematic review of the literature using search terms relating to SCD up till 2019, we identified relevant descriptive publications for inclusion. The scope of this review is mainly an overview of the clinical features of pain, the cardinal symptom in SCD, which present following the drop in foetal haemoglobin as young as five to six months after birth. The relative impact of haemolysis and small-vessel occlusive pathology remains controversial, a combination of features probably contribute to the different pathologies. We also provide an overview of emerging therapies in SCD. Full article

Galactosaemia has been included in various newborn screening programs since 1963. Several methods are used for screening; however, the predominant methods used today are based on the determination of either galactose-1-phosphate uridyltransferase (GALT) activity or the concentration of total galactose. These methods cannot be multiplexed and therefore require one full punch per sample. Since the introduction of mass spectrometry in newborn screening, many diseases have been included in newborn screening programs. Here, we present a method for including classical galactosaemia in an expanded newborn screening panel based on the specific determination of galactose-1-phosphate by tandem mass spectrometry. The existing workflow only needs minor adjustments, and it can be run on the tandem mass spectrometers in routine use. Furthermore, compared to the currently used methods, this novel method has a superior screening performance, producing significantly fewer false positive results. We present data from 5500 routine newborn screening samples from the Danish Neonatal Screening Biobank. The cohort was enriched by including 14 confirmed galactosaemia positive samples and 10 samples positive for other metabolic disorders diagnosed through the Danish newborn screening program. All galactosaemia positive samples were identified by the method with no false positives. Furthermore, the screening performance for other metabolic disorders was unaffected. Full article

The prevalence of metabolic disorders in Nepal is yet unknown, although many case reports occur in literature. Heel-prick blood samples from newborns were collected on Dried Blood Spot (DBS) collection cards and tested through Tandem Mass Spectroscopy and fluorescence assays for disorders included in the Swiss neonatal screening program; two cases of hypothyroidism and one case of cystic fibrosis were identified. Thyroid stimulating hormone (TSH), immuoreactive trypsinogen (IRT), hydroxyprogesterone (OHP), tyrosine (Tyr), and octanoylcarnitine (C8) showed significant differences with gestation age. Most of the parameters were positively correlated with each other except galactose, galactose 1 phosphate uridyl transferase (GALT), and biotinidase. First and ninety-ninth percentiles in the Nepalese newborns were found to be different when compared with the Swiss newborns. Congenital hypothyroidism and cystic fibrosis are candidates to be considered for a newborn screening program in Nepal. Differences between the Nepalese and Swiss newborns in parametric values that change with gestation age can be attributed to a higher survival rate of pre-term babies in Switzerland. Others could be explained in part by early and exclusive breastfeeding in Nepalese newborns. Full article

For newborn screening (NBS) of lysosomal storage diseases, programs measure enzymatic activities in dried blood spots (DBS) and, in most cases, act on samples where the measurement is below a specific cutoff value. The rate of false positives and negatives in any NBS program is of critical importance. The measured values across a population of newborns are governed by many factors, and in this article we focus on assay imprecision. Assay parameters including the Analytical Range and the Z-Factor have been discussed as a way to compare assay performance for NBS of lysosomal storage diseases. Here we show that these parameters are not rigorously connected to the rate of false positives and negatives. Rather, it is the assay imprecision near the screen cutoff that is the most important parameter that determines the rate of false positives and negatives. We develop the theoretical treatment of assay imprecision and how it is linked to screen performance. What emerges is a useful type of parametric plot that allows for rigorous assessment of the effect of assay imprecision on the rate of false positives and false negatives that is independent of the choice of screen cutoff value. Such plots are useful in choosing cutoff values. They also show that a high assay imprecision cannot be overcome by changing the cutoff value or by use of postanalysis, statistical tools. Given the importance of assay imprecision near the cutoff, we propose that quality control DBS are most useful if they span a range of analyte values near the cutoff. Our treatment is also appropriate for comparing the performance of multiple assay platforms that each measure the same quantity (i.e., the enzymatic activity in DBS). The analysis shows that it is always best to use the assay platform that gives the lowest imprecision near the cutoff. Full article