Implementation of newborn screening for mucopolysaccharidosis type IVA and long-term monitoring in Taiwan

Purpose: Mucopolysaccharidosis IVA (MPS IVA) is a rare lysosomal storage disorder arising from a deficiency in N-acetylgalactosamine-6-sulfatase. Methods: From September 2019 to October 2023, a total of 264,843 Taiwanese newborns underwent screening for MPS IVA using dried blood spots and tandem mass spectrometry. Results: Among the 95 referred infants, 9 (9%) were confirmed to have MPS IVA (group 1), 18 (19%) were highly suspected to have MPS IVA (group 2), 61 (64%) were identified as heterozygotes of MPS IVA (group 3), and 7 (7%) were determined not to have MPS IVA (group 4). A total of 34 different GALNS (HGNC:4122) gene variants were identified through our MPS IVA newborn screening program. The most prevalent variant was c.857C>T p.(Thr286Met), found in 33 cases (29%), followed by c.953T>G p.(Met318Arg) in 22 cases (19%). Intravenous enzyme replacement therapy was initiated in 5 patients at ages ranging from 0.3 to 1.7 years. The estimated incidence of MPS IVA in this screening program was 3.4 per 100,000 live births. Conclusion: Because of the progressive nature of MPS IVA, an early diagnosis facilitated by newborn screening and prompt initiation of enzyme replacement therapy before irreversible organ damage occurs may result in improved clinical outcomes.