Figure 1.
The flowchart illustrating the stages of newborn screening from April 2020 to March 2025. The process begins with 1,380,634 newborns undergoing TREC/KREC screening. It splits into two paths: laboratories performing repeat sampling (1,348,062) and laboratories without repeat sampling (32,572). In the repeat sampling path, 3,425 newborns have abnormal screening results, followed by repeat sampling, resulting in 687 abnormal results. In the non-repeat sampling path, 182 newborns have abnormal screening results. The total referrals amount to 869, categorized into low TREC only (488), low KREC only (319), and low TREC and KREC (62). The final diagnoses include SCID (15), XLA and other agammaglobulinemias (16), and sTCL (9).
Flow diagram of NBS for IEIs in Japan (April 2020–March 2025). The diagram shows the total number of newborns screened, those requiring repeat sampling, referrals to IEI centers, and the final confirmed diagnoses. 30 laboratories performed repeat sampling. Two laboratories directly referred infants with low initial TREC/KREC values.