Newborn Screening for Presymptomatic Diagnosis of Complement and Phagocyte Deficiencies

Abstract

The clinical outcomes of primary immunodeficiencies (PIDs) are greatly improved by accurate diagnosis early in life. However, it is not common to consider PIDs before the manifestation of severe clinical symptoms. Including PIDs in the nation-wide newborn screening programs will potentially improve survival and provide better disease management and preventive care in PID patients. This calls for the detection of disease biomarkers in blood and the use of dried blood spot samples, which is a part of routine newborn screening programs worldwide. Here, we developed a newborn screening method based on multiplex protein profiling for parallel diagnosis of 22 innate immunodeficiencies affecting the complement system and respiratory burst function in phagocytosis. The proposed method uses a small fraction of eluted blood from dried blood spots and is applicable for population-scale performance. The diagnosis method is validated through a retrospective screening of immunodeficient patient samples. This diagnostic approach can pave the way for an earlier, more comprehensive and accurate diagnosis of complement and phagocytic disorders, which ultimately lead to a healthy and active life for the PID patients.

Keywords: complement deficiencies; dried blood spot; newborn screening; phagocytic disorders; presymptomatic diagnosis; primary immunodeficiency; protein profiling.

Figure 1

Schematic view of the screening procedure. Drops of blood (~70 μL) are dried on filter paper. Proteins are eluted and labeled from a punched disc, equal to a 4.5% fraction of one blood drop. After further dilution (1:500 dilution of blood), proteins are captured on the designed antibody-coupled bead array, and signals are analyzed with fluorescent-based readout. Stars illustrated fluorescent label. Two laser beams are applied for detection of beads (capture antibodies) and associated fluorescent signal (from labeled target proteins).

Figure 2

Data from retrospective PID screening. Protein profiling is done in parallel in a multiplexed measurement and obtained values are shown in separate boxplots for different disorders from 37 healthy control samples including 21 newborn dried blood spots. The deficiency level (IQR ≥ 1.5) is shown as a red baseline. Deficient samples (n = 41) are shown in colored asterisks, including five newborn dried blood spots of original Guthrie cards from newborn screening program in Sweden. SCN stands for severe congenital neutropenia.