Newborn screening, genetic analysis, and long-term follow-up of 89 cases with short-chain acyl-CoA dehydrogenase deficiency (SCADD)

Objective: This study aimed to delineate the neonatal screening landscape, incidence, tandem mass spectrometry (MS/MS)-based metabolic signatures, ACADS gene variant spectrum, and long-term clinical outcomes of short-chain acyl-CoA dehydrogenase deficiency (SCADD) in newborns from Zhejiang Province, China. Methods: A retrospective cohort study was conducted on 4,667,883 newborns in Zhejiang screened between November 2013 and August 2025. Acylcarnitine profiles in dried blood spots were analyzed by MS/MS. Urinary organic acids and ACADS gene variants were detected via gas chromatography-mass spectrometry (GC-MS) and high-throughput sequencing, respectively. Confirmed SCADD patients underwent longitudinal follow-up to evaluate growth, neurodevelopment, and biochemical parameters. Results: Initial screening identified 500 infants with elevated butyrylcarnitine (C4) or C4/ propionylcarnitine (C3) ratios; 89 were confirmed as SCADD, corresponding to an incidence of 1 in 52,448 (1.9 per 100,000). All patients were asymptomatic during the neonatal period. Among the 26 patients who underwent urinary GC/MS, 25 (96.2%) presented with elevated ethylmalonic acid (EMA) levels. Fifty-one ACADS variants were identified, with missense variants (46/51, 90.2%) being the most prevalent; the top three variants were c.1031 A > G (28.1%), c.164C > T (13.5%), and c.1130C > T (11.2%). Conclusions: The incidence of SCADD in Zhejiang is 1 in 52,448, with c.1031 A > G and c.164C > T as the most frequent ACADS variants; and most screen-detected SCADD cases remain asymptomatic.