Potential for a large-scale newborn screening strategy for sickle cell disease in Mali: A comparative diagnostic performance study of two rapid diagnostic tests (SickleScan® and HemotypeSC®) on cord blood

Sickle cell disease (SCD) is a life-threatening disease requiring reliable early diagnosis. We assessed the acceptability and diagnostic performances of two rapid diagnostic tests (RDTs) to identify SCD (HbSS, HbSC, HbS/β-thalassaemia) or SCD carrier (HbS/HbC) in a pilot SCD newborn screening (NBS) strategy in Mali. All consenting delivering women were offered SCD NBS using cord blood sampling on two RDTs (SickleScan® and HemotypeSC®) compared to the high-performance liquid chromatography (HPLC) gold standard to detect SCD states. From April 2021 to August 2021, 4333 delivering women were eligible of whom 96.1% were offered NBS: 1.6% refused, 13.8% delivered before consenting and 84.6% consented; 3648 newborns were diagnosed by HPLC; 1.64% had SCD (0.63% HbSS, 0.85% HbSC, 0.16 HbS/β-plus-thalassaemia); 21.79% were SCD carrier. To detect accurately SCD, SickleScan® had a sensitivity of 81.67% (95% confidence interval [CI]: 71.88-91.46) and a negative predictive value (NPV) of 99.69% (95% CI: 99.51-99.87); HemotypeSC® had a sensitivity of 78.33% (95% CI: 67.91-88.76) and a NPV of 99.64% (95% CI: 99.44-99.83). To detect SCD carrier: SickleScan® sensitivity was 96.10% (95% CI: 94.75-97.45) and NPV, 98.90% (95% CI: 98.51-99.29); HemotypeSC® sensitivity was 95.22% (95% CI: 93.74-96.70) and NPV, 98.66% (95% CI: 98.24-99.03). Routine SCD NBS was acceptable. Compared with HPLC, both RDTs had reliable diagnostic performances to exclude SCD-free newborns and to identify SCD carriers to be further confirmed. This strategy could be implemented in large-scale NBS programmes.

Recent advances in screening and diagnosis of hemoglobinopathy

Introduction: Hemoglobinopathies are important causes of inherited disorders with substantial mortality and morbidity across the world. Therefore, proper utilization of available screening and diagnostic techniques are important for its diagnosis and management.Areas covered: In this review, the authors attempt to summarize clinical presentations, give a brief account of existing techniques, and discuss evolving and advanced techniques for detection and screening of the condition. As prevention of the disease condition is an important community measure to control the disease, techniques involving newborn screening, antenatal diagnosis, and point of care tests have been described in addition to more advanced molecular and protein diagnostics. The literature search in this area is covered between 1980 and 2018 with PubMed as the main source along with authors' own research in this area.Expert opinion: Screening and detection of hemoglobinopathy is best accomplished by a hierarchical approach with the optimum blend of old and newer techniques. Starting with point of care techniques through the commonly used HPLC and high voltage capillary electrophoresis, or modern and high throughput molecular biology and mass spectroscopic techniques can be used depending on specific situations. Every country needs to optimize its techniques depending on the frequency of the problem and available resources.

Newborn Screening for Sickle Cell Disease in Europe

The history of newborn screening (NBS) for sickle cell disease (SCD) in Europe goes back almost 40 years. However, most European countries have not established it to date. The European screening map is surprisingly heterogenous. The first countries to introduce sickle cell screening on a national scale were France and England. The French West Indies started to screen their newborns for SCD as early as 1983/84. To this day, all countries of the United Kingdom of Great Britain and Northern Ireland have added SCD as a target disease to their NBS programs. The Netherlands, Spain and Malta also have national programs. Belgium screens regionally in the Brussels and Liège regions, Ireland has been running a pilot for many years that has become quasi-official. However, the Belgian and Irish programs are not publicly funded. Italy and Germany have completed several pilot studies but are still in the preparatory phase of national NBS programs for SCD, although both countries have well-established concepts for metabolic and endocrine disorders. This article will give a brief overview of the situation in Europe and put a focus on the programs of the two pioneers of the continent, England and France.

Neonatal Screening for Sickle Cell Disease in Belgium for More than 20 Years: An Experience for Comprehensive Care Improvement

Our previous results reported that compared to sickle cell patients who were not screened at birth, those who benefited from it had a lower incidence of a first bacteremia and a reduced number and days of hospitalizations. In this context, this article reviews the Belgian experience on neonatal screening for sickle cell disease (SCD). It gives an update on the two regional neonatal screening programs for SCD in Belgium and their impact on initiatives to improve clinical care for sickle cell patients. Neonatal screening in Brussels and Liège Regions began in 1994 and 2002, respectively. Compiled results for the 2009 to 2017 period demonstrated a birth prevalence of sickle cell disorder above 1:2000. In parallel, to improve clinical care, (1) a committee of health care providers dedicated to non-malignant hematological diseases has been created within the Belgian Haematology Society; (2) a clinical registry was implemented in 2008 and has been updated in 2018; (3) a plan of action has been proposed to the Belgian national health authority. To date, neonatal screening is not integrated into the respective Belgian regional neonatal screening programs, the ongoing initiatives in Brussels and Liège Regions are not any further funded and better management of the disease through the implementation of specific actions is not yet perceived as a public health priority in Belgium.

New approach to accurate interpretation of sickle cell disease newborn screening by applying multiple of median cutoffs and ratios

BACKGROUND

The main goal of newborn screening (NBS) for sickle cell disease (SCD) is to detect affected neonates so that specific preventive care can be implemented. High-performance liquid chromatography (HPLC) used for NBS has high sensitivity and specificity, but we lack guidelines for quantitative hemoglobin (Hb) fraction interpretation. The purpose of this study was to determine cutoff values to standardize quantitative interpretation in SCD NBS for different clinical situation such as, red blood cell transfusion or beta-thalassemia, which can be real screening pitfalls.

METHODS

Retrospective study of 75,026 samples from the neonatal screening program analyzed in our laboratory. Precise HbA and HbS percentages at birth were recorded and median values established for each gestational age, allowing percentage results to be expressed in normal gestation-specific multiples of the median (MoM). Three threshold values of clinical interest were determined.

RESULTS

High levels of HbA (>2.5 MoM) allowed identification of newborns who received transfusions. Low levels of HbS (≤0.7 MoM) allowed detection of the association between HbS and other mutations of the beta-globin gene (i.e., HbHope, β0-thalassemia, etc.). An HbA/HbS ratio <0.5 to distinguish healthy carriers from SCD with S/β+-thalassemia. The screening accuracy for each threshold was established. The screening accuracy of low-level HbA, which is determinant in identifying the subgroup of patients at risk of β-thalassemia, will be determined prospectively.

CONCLUSIONS

This new approach introduces tools for a quantitative interpretation in SCD NBS by HPLC methods and could allow standardization of interpretation between centers.

Automated capillary electrophoresis in the screening for hemoglobinopathies

Hemoglobinopathies are genetic disorders of globin chains characterized by the decreased expression of α- or β-globin chains (thalassemias) or by the synthesis of an abnormal protein (hemoglobin variants in, e.g., sickle cell disease). The screening of most hemoglobinopathies relies, together with hematological results and clinical elements, on the separation and quantification of normal and abnormal hemoglobin fractions. Gel electrophoresis, isoelectric focusing, and HPLC have been the methods of choice for many years. For about 20 years, capillary electrophoresis has appeared as a strong alternative method. Since the early 2000s, automated instruments are commercially available for the analysis of Hb fractions in adult patients but also for neonatal screening.