Lawrence Greed

Newborn screening (NBS) bloodspots are primarily used to test for a defined panel of conditions, yet screening expansion has necessitated the implementation of new tests. Integral to test implementation across all clinical laboratories is the need to evaluate the method with clinical samples, and a common secondary use of residual bloodspots, which are samples that remain following conventional screening, is validating new testing methods by establishing “normal” analyte concentrations and setting action decision limits for NBS protocols prior to implementation. Analysis of de-identified residual bloodspots may potentially reveal an infant with a treatable condition, and re-identification and clinical notification of the infant may then be prudent. However, consent to test residual samples for conditions under implementation may not have been obtained. This ethical dilemma risks the inclusion of residual bloodspots in test development being declined by over-arching NBS authorities. Consequently, the Human Genetics Society of Australasia (HGSA) NBS Committee issued a survey to the Australasian NBS laboratories regarding the current practices of the use of residual bloodspots for new test implementation. The questionnaire revealed a consistent requirement for residual NBS bloodspot analysis to determine reference ranges and screening cutoffs for biochemical variants. If using de-identified residual samples as a component of test validation, re-identification of infants with out-of-range results for clinical referral was considered ethically justified for potentially treatable conditions. The survey results will be used to develop a consensus approach in the region that is both ethically and scientifically valid.

A greater number of screened conditions is often considered to equate to better screening, whereas it may be due to conditions being counted differently. This manuscript describes a harmonised Australasian approach to listing target conditions found on bloodspot screening panels. Operational definitions for target disorders and incidental findings were developed and applied to disorder lists. A gap analysis was performed between five, state-based Australian newborn screening programme disorder lists and the single national New Zealand and state-level Californian versions. Screening panels were found to be broadly similar. Gap analysis with Californian data reflected differences in jurisdictional approval (for example, haemoglobinopathies and lysosomal disorders not being recommended in Australasia). Differences amongst Australasian panels reflected varied the timeframes recommended in order to implement newly approved disorders, as well as decisions to remove previously screened disorders. A harmonised approach to disorder counting is essential to performing valid comparisons of newborn bloodspot screening panels.