Recent advances in the treatment of spinal muscular atrophy (SMA) have dramatically altered prognosis. Rather than a rapidly lethal disease, SMA type 1, the most severe form with the earliest onset of SMA, has become a disease in which long-term event-free survival with the acquisition of important motor milestones is likely. Prognosis for patients with SMA type 2 has shifted from slow and progressive deterioration to long-term stability. Nevertheless, there is a large heterogeneity in terms of clinical response to currently available treatments, ranging from absence of response to impressive improvement. The only factor identified that is predictive of treatment success is the age of the patient at the initiation of treatment, which is closely related to disease duration. The aim of this paper is to review available evidence that support early intervention using currently available treatment approaches.

Background: In spinal muscular atrophy, clinical trial results indicated that disease-modifying treatments are highly effective when given prior to symptom onset, which has prompted newborn screening programs in growing number of countries. However, prognosis of those patients cannot be inferred from clinical trials conducted in presymptomatic individuals, as in some cases disease presents very early. Methods: we conducted a systematic review of articles published up to January 2023. Results: Among 35 patients with three SMN2 copies treated before 42 days of age and followed-up for at least 18 months, all but one achieved autonomous ambulation. Of 41 patients with two SMN2 copies, who were non-symptomatic at treatment initiation, all achieved a sitting position independently and 31 were able to walk. Of 16 patients with two SMN2 copies followed-up for at least 18 months who presented with symptoms at treatment onset, 3 achieved the walking milestone and all but one were able to sit without support. Conclusions: evaluation of data from 18 publications indicates that the results of early treatment depend on the number of SMN2 copies and the initial neurological status of the patient.

Purpose: Genomic newborn screening programs are emerging worldwide. With the support of the local pediatric team of Liege, Belgium, we developed a panel of 405 genes that are associated with 165 early-onset, treatable diseases with the goal of creating a newborn screening test using targeted next-generation sequencing for all early-onset, treatable, and serious conditions. Methods: A process was developed that informed the future parents about the project and collected their consent during a face-to-face discussion with a trained investigator. The first baby was screened on 1 September 2022. The main objective of the study was to test the feasibility and the acceptability of targeted sequencing at birth as a first-tier newborn screening approach to detect treatable genetic conditions or genetic conditions for which a pre-symptomatic or early symptomatic clinical trial is available. Results: As of 20 June 2024, the parents of 4425 children had been offered the test; 4005 accepted (90.5%) and 420 refused (9.5%). The main reasons for refusal were the research nature of the project and the misunderstanding of what constitutes genetic conditions. Conclusions: These data demonstrate the high acceptability of genomic newborn screening in a properly informed population.