Expanded Newborn Screening for Inborn Errors of Metabolism at a Single Center in Louisiana (2005–2024): Outcomes

This study evaluates the incidence of metabolic disorders detected from January 2005 to December 2024 and their clinical outcomes. Data were retrospectively collected from the Louisiana Newborn Screening database. Clinical outcomes were obtained through review of corresponding medical records. In addition, an electronic questionnaire assessing educational attainment and neurodevelopmental disorders was sent to the patients' families. Of 1,230,356 infants screened, 478 were diagnosed with metabolic disorders, corresponding to an incidence of 1 in 2574 live births. The three most commonly identified conditions were biotinidase deficiency, phenylketonuria (PKU), and medium-chain acyl-CoA dehydrogenase deficiency (MCADD). During the study period, at least 11 patients died. The program demonstrated a false-positive rate of 0.93%. Twelve patients (7%) were symptomatic before or at the time of NBS result notification. Recurrent metabolic decompensations occurred in 3 of 4 maple syrup urine disease (MSUD) cases, 7 of 7 methylmalonic acidemia (MMA) cases, 1 of 4 propionic acidemia (PA) cases and 1 of 7 urea cycle defect cases. Regarding long-term outcomes, 45.7% of survey respondents reported adverse neurodevelopmental outcomes of varying severity. Early detection and timely intervention have contributed to normal or near-normal outcomes in many cases. However, the morbidity and mortality observed in some patients despite early diagnosis highlights the severity and complexity of certain metabolic conditions. Additionally, the relatively high false positive rate underscores the need for ongoing efforts to improve the specificity of screening protocols to reduce unnecessary follow-ups and mitigate potential stress for families.