Next-Generation Sequencing in Newborn Screening: A Review of Current State

Abstract

Newborn screening was first introduced at the beginning of the 1960s with the successful implementation of the first phenylketonuria screening programs. Early expansion of the included disorders was slow because each additional disorder screened required a separate test. Subsequently, the technological advancements of biochemical methodology enabled the scaling-up of newborn screening, most notably with the implementation of tandem mass spectrometry. In recent years, we have witnessed a remarkable progression of high-throughput sequencing technologies, which has resulted in a continuous decrease of both cost and time required for genetic analysis. This has enabled more widespread use of the massive multiparallel sequencing. Genomic sequencing is now frequently used in clinical applications, and its implementation in newborn screening has been intensively advocated. The expansion of newborn screening has raised many clinical, ethical, legal, psychological, sociological, and technological concerns over time. This review provides an overview of the current state of next-generation sequencing regarding newborn screening including current recommendations and potential challenges for the use of such technologies in newborn screening.

Use of Molecular Genetic Analyses in Danish Routine Newborn Screening

“…However, for such strategy we need to have an in-depth knowledge about how the molecular pathology is related to clinical manifestations or the lack of these [4]. Such knowledge is not always available [7], and we need to collect more molecular genetic data into generally available variant databases together with clinical data. Second-tier molecular genetic testing may also provide the clinician with important prognostic information, where examples may be similar to those described for the mild variants in ACADM and IVD above.…”

“…Similar to Denmark, NGS is used in Norway as part of CF NBS and as second-tier testing for metabolic diseases [5,34]. The UK has started analysing the use of NGS in NBS [10], but otherwise experience is still limited [6,7]. There are a number of disease candidates for NGSbased diagnostics, such as MCADD, VLCADD, IVA and CF mentioned above.…”

“…At present, seven genes are known to cause characteristic MADD acylcarnitines and potential riboflavin-responsive and treatable diseases, which could be tested for with NGS as a second-tier test [35]. However, more recently, genetic deficiencies of respiratory chain complexes have also been associated with MADD-like acylcarnitines [36,37]; this challenges and possibly leads to the extension of the genetic evaluation, increasing the risk of identifying variants with unknown clinical relevance or associated with late-onset and untreatable diseases, which are not a focus for NBS [7].…”

“…Another goal for the first-tier use of molecular genetic methods would be to increase the adaptability of NBS making it possible to diagnose treatable diseases without a reliable biochemical biomarker [13]; thus, as shown here for intermittent MSUD, non-classical variants may not be diagnosed by routine biochemical screening [39][40][41]. Additionally, there is a general wish in many countries to increase the number of diseases on NBS panels, and molecular genetic analyses would be able to fulfil this need because the methods are generally applicable for most inherited diseases [7,11]. New therapies are being developed quickly for a number of inherited diseases with many therapies being dependent on early therapeutic initiation shortly after birth; one example is the quickly advancing therapeutic advances in spinal muscular atrophy which have been answered by a quick introduction of a molecularly based newborn screening for SMA in some countries, e.g., in Belgium [42] and very soon in Denmark.…”

“…For confirmation of the screening positive samples, further biochemical methods are commonly used together with molecular genetic studies using new samples from the child. In recent years, molecular genetic studies have been introduced as second-tier testing before contacting the family for confirmative evaluation [1,[4][5][6][7]; even the use of molecular genetic studies as first-tier analyses has been introduced when screening for spinal muscular atrophy (SMA) and severe combined immunodeficiency (SCID) [4], and further use of molecular genetics as a first-tier procedure in NBS is being discussed. In Denmark, we have recently introduced molecular genetic analyses for SCID (though, strictly speaking, not a variant analysis) as first-tier screening, and SMA has also been accepted for addition to the routine screening panel with the use of first-tier molecular genetic analyses.…”