Newborn screening (NBS) has widely been utilized in developed countries as a cost-effective public health strategy that reduces morbidity and mortality. Developing countries, however, are new to the NBS scene and have their own unique challenges, both in instituting the program as well as effectively acting on the results. NBS offers numerous ethical issues on a global scale, however, here we argue that there are unique ethical issues surrounding the development and expansion of newborn screening in Latin America given its highly heterogenous population. Once a NBS program is effectively instated, ethical considerations continue when pursuing expansion of screening to include further conditions. While Latin America grapples with the ethics of expanded newborn screening (ENBS), some developed countries discuss utility of genomic sequencing technologies in the newborn population. When the ability to detect further pathology is expanded, one must know what to do with this information. As rare diseases are identified either on ENBS or via genome sequencing, access to treatments for these rare diseases can be a real challenge. If we consider newborn screening as a global initiative, then we need more than a deontology approach to analyze these challenges; we need an approach that considers the unique characteristics of each territory and tremendous heterogeneity that exists prior to the implementation of these programs. As genomic technology advances further in the developed world, while some developing countries still lack even basic newborn screening, there is a further widening of the gap in global health disparities. The question is posed as to who has responsibility for these newborns’ lives on an international level. Without an approach towards newborn screening that accounts for the diverse global population, we believe optimal outcomes for newborns and families across the world will not be achieved.

There are concerns about muscle and bone health in patients with Phenylketonuria (PKU). Our aim was to compare muscle mass, function, and bone health among young adults with PKU who maintained or suspended dietary treatment. Methods: Three groups were considered—PKU-1: 10 patients who used a protein substitute (PS) without phenylalanine (Phe); PKU-2: 14 patients who used the PS without Phe until eighteen years old and then practiced mostly a vegan diet; and 24 matched healthy controls. A 24 h recall survey, blood parameters, body composition and bone mineral density through DEXA, rectus femoris thickness by ultrasound, hand grip strength, submaximal exercise test, and walking speed were assessed. Results: PKU-1 patients had lower hand grip strength than their matched controls, but no other differences. Compared to controls, the PKU-2 group had lower fat-free mass (p = 0.01), less spine and femoral bone mineral density (p = 0.04 and p < 0.01, respectively), and peak workload on the incremental test (p = 0.03). When comparing PKU groups, blood Phe levels were significantly lower in the PKU-1 group (p = 0.02). Conclusions: Among PKU patients, abandoning the dietary treatment and maintaining high blood Phe concentrations could be deleterious for muscles and bones. However, we cannot discard other causes of bone and muscle damage in these patients.

Part of the vision of the ISNS is ‘to enhance the quality of neonatal screening and medical services through dissemination of information, guidelines and best practices.’ Although newborn screening encompasses testing in the newborn period for critical congenital heart disease, hearing impairment, birth defects, and congenital biochemical disorders (usually on bloodspots), this guideline is specifically about bloodspot screening. The ISNS has provided neonatal screening guidelines for many years and here presents the renewed 2025 General Guidelines for Neonatal Bloodspot Screening. They are intended to provide a framework for screening programs to develop specific policies around all aspects of the newborn screening system, offering the basic set of items for consideration. These guidelines provide trusted anchors to build, expand, or maintain robustly organized neonatal or newborn screening (NBS) programs and a checklist to evaluate and improve the essential elements of those programs. For starting or developing programs, it is a set of elements for which provisions need to be in place and a checklist of items that the screening program should at a minimum have provisions for. The publication of these guidelines is meant as a starting point for interactive discussion, to further improve this document and expand where necessary.

Hepatocellular carcinoma (HCC) is a major complication of tyrosinemia type 1 (HT-1), an inborn error of metabolism affecting tyrosine catabolism. The risk of HCC is higher in late diagnoses despite treatment. Alpha-fetoprotein (AFP) is widely used to detect liver cancer but has limitations in early-stage HCC detection. This study aimed to implement a machine-learning (ML) approach to identify the most relevant laboratory variables to predict AFP alteration using constrained multidimensional data from Chilean and Italian HT-1 cohorts. A longitudinal retrospective study analyzed 219 records from 35 HT-1 patients, including 8 with HCC and 5 diagnosed through newborn screening. The dataset contained biochemical and demographic variables that were analyzed using the eXtreme Gradient Boosting algorithm, which was trained to predict abnormal AFP levels (>5 ng/mL). Four key variables emerged as significant predictors: alanine transaminase (ALT), alkaline phosphatase, age at diagnosis, and current age. ALT emerged as the most promising indicator of AFP alteration, potentially preceding AFP level changes and improving HCC detection specificity at a cut-off value of 29 UI/L (AUROC = 0.73). Despite limited data from this rare disease, the ML approach successfully analyzed follow-up biomarkers, identifying ALT as an early predictor of AFP elevation and a potential biomarker for HCC progression.