Clinical Utility of the Addition of Molecular Genetic Testing to Newborn Screening for Sickle Cell Anemia

Abstract

Sickle cell disease (SCD) is a group of related yet genetically complex hemoglobinopathies. Universal newborn screening (NBS) for SCD is performed in the United States and many other nations. Classical, protein-based laboratory methods are often adequate for the diagnosis of SCD but have specific limitations in the context of NBS. A particular challenge is the differentiation of sickle cell anemia (SCA) from the benign condition, compound heterozygosity for HbS and gene-deletion hereditary persistence of fetal hemoglobin (HbS/HPFH). We describe a sequential cohort of 44 newborns identified over 4.5 years who had molecular genetic testing incorporated into NBS for presumed SCA (an “FS” pattern). The final diagnosis was something other than SCA in six newborns (12%). Three (7%) had HbS/HPFH. All had a final, correct diagnosis at the time of their first scheduled clinic visit in our center (median 8 weeks of age). None received initial counseling for an incorrect diagnosis. In summary, genetic testing as a component of NBS for SCD is necessary to provide correct genetic counseling and education for all newborns' families at their first visit to a sickle cell center. Genetic testing also permits the use of early, pre-symptomatic hydroxyurea therapy by preventing infants with HbS/HPFH from receiving unnecessary therapy. We argue that genetic testing should be incorporated into contemporary NBS for SCD.

Scalable noninvasive amplicon-based precision sequencing (SNAPseq) for genetic diagnosis and screening of β-thalassemia and sickle cell disease using a next-generation sequencing platform

“…Most antenatal screening and newborn screening (NBS) programs utilize protein-based hemoglobin separation techniques such as isoelectric focusing (IEF), HPLC, and gel- or liquid-based electrophoresis ( Ryan et al, 2010 ; Therrell et al, 2015 ). Although protein-based techniques form the basis of hemoglobin diagnostics, they may not be able to identify BT mutations or distinguish between HbSS and compound heterozygosity for HbS ( Belhoul et al, 2013 ; Shook et al, 2021 ). They are also time consuming and additional confirmatory tests are necessary to confirm diagnosis which delays point-of care.…”

“…Thus, multiple diagnostic steps may lead to misdiagnosis, delayed treatment, and overlooking of mutation carriers requiring counseling. There are multiple literature reporting pitfalls of currently used for hemoglobinopathies screening programs in prevention and therapy of hemoglobinopathies ( Belhoul et al, 2013 ; Shook et al, 2021 ). In addition, the diagnostic differentiation is now time-sensitive and crucial due to the rising use of early, pre-symptomatic disease-modifying medication (e.g., initiation of hydroxyurea therapy at 6 months of age) ( Ware et al, 2019 ).…”

Scalable noninvasive amplicon-based precision sequencing (SNAPseq) for genetic diagnosis and screening of β-thalassemia and sickle cell disease using a next-generation sequencing platform

“…The majority of newborn screening (NBS) programs utilize protein-based hemoglobin separation methods such as isoelectric focusing (IEF), HPLC, and gel or liquid-based electrophoresis 25 . Though protein-based techniques are the basis of hemoglobin diagnostics, they may not be able to identify BT mutations or to distinguish between HbSS and compound heterozygosity for HbS and hereditary persistence of fetal hemoglobin (HbS/HPFH) 26 . Hence, additional confirmation of mutation is required by DNA sequencing.…”

Determination of birth prevalence of sickle cell disease using point of care test HemoTypeSC TM at Rundu hospital, Namibia

“…High performance liquid chromatography (HPLC and isoelectric focusing( IEF) are the two main laboratory techniques for haemoglobinopathy screening currently suitable for routine use and have been used in developed countries and several studies in Africa (18). Molecular genetic tests are considered the gold standard tests as they target the affected genes and are able to distinguish the different mutations (19). These include Restriction Fragment Polymorphism (RFLP) partial restriction of deoxyribonucleic acid (DNA), Real-time polymerase chain reaction (PCR) (20) and DNA sequencing which is the most expensive molecular method compared to RFLP and PCR because of reagents, instrumentation, personnel and review time required for analysis, but it provides the most comprehensive data for beta-globin gene (20).…”