Primary immunodeficiency diseases (PIDs) are a group of disorders caused by abnormalities in a single gene that result in immune dysfunction, with over 500 distinct subtypes. For severe combined immunodeficiency (SCID) caused by T cell deficiency and agammaglobulinemia caused by B cell deficiency (BCD)—the most severe forms of PID—we have developed a newborn screening (NBS) method using T cell receptor excision circles (TREC) and immunoglobulin kappa-deleting recombination excision circles (KREC) quantitative PCR (qPCR) and have been working to implement it nationwide.
In particular, through a Japan Agency for Medical Research and Development (AMED) research group established in fiscal year 2019, we developed a domestically produced qPCR assay kit that also includes the SMN1 gene, whose abnormality causes spinal muscular atrophy (SMA). Although currently offered as an optional test, the release of kits by other companies has made PID-NBS testing available nationwide. Furthermore, under the Children and Families Agency’s fiscal year (FY)2023 supplementary budget, SCID and SMA were selected as target diseases for a demonstration project. In the first year, 13 prefectures were selected; in FY2024, 27 prefectures; and in FY2025, 38 prefectures. As a result, approximately 700,000 newborns per year can now undergo PID-NBS at public expense. This demonstration project requires us to “demonstrate” the utility of PID screening, particularly for SCID, and surveys and analyses are being conducted primarily by the Technical Committee of the Japanese Society for Mass Screening and the Newborn Screening Working Group of the Japanese Society for Immunodeficiency and Autoinflammatory Diseases (JSIAD). Through this demonstration project, the full public funding of SCID-NBS means that a future is just around the corner where infants with SCID in Japan can be safely and completely cured through hematopoietic cell transplantation without suffering infections.
In this talk, I will provide an overview of the current status and future prospects of the Children and Families Agency Newborn Screening Demonstration Project for primary immunodeficiencies.
