Simona Lucchi

X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder, caused by mutations in the ABCD1 gene. Early diagnosis is critical to manage adrenal insufficiency and cerebral forms of the disease. Since 2021, a pilot newborn screening (NBS) program for X-ALD has been launched in Lombardy, Italy. From September 2021 to June 2025, 138,116 newborns (≥37 weeks’ gestational age) were screened for elevated C26:0-lysophosphatidylcholine (C26:0-LPC) levels using a two-tier algorithm. Genetic testing was performed in non-negative cases. Males found to be ABCD1 variant carriers were enrolled in multidisciplinary follow-up, including neurological, endocrinological, and nutritional assessments. Eleven individuals (six males, five females) carried pathogenic or likely pathogenic ABCD1 variants. Three males were diagnosed with adrenal insufficiency and started hydrocortisone therapy between 1 and 2 years of age. Growth parameters were within normal range overall, but two children showed signs of stunting associated with poor dietary compliance. Additionally, three patients were diagnosed with Zellweger spectrum disorders (ZSDs). No patients affected with Aicardi-Goutières Syndrome were identified. Newborn screening for X-ALD in Italy is feasible and enables early detection and intervention. Biochemical markers and genetic analysis are reliable tools for identifying affected males and female carriers. Multidisciplinary management is essential to address medical and psychosocial challenges during follow-up.

Acetoacetyl-CoA thiolase deficiency, also known as Beta-ketothiolase deficiency (BKTD), is an autosomal recessive organic aciduria included in the Italian newborn screening (NBS) panel. It is caused by mutations in the ACAT1 gene, which encodes the mitochondrial acetyl-CoA acetyltransferase. Its deficiency impairs the degradation of isoleucine and acetoacetyl-CoA, leading to the accumulation of toxic metabolites. We describe three cases of BKTD. The first newborn showed increase in C5:1, C4DC/C5OH, C3DC/C4OH in the NBS. Urinary organic acids (uOAs) revealed marked excretion of 2-methyl-3-hydroxybutyrate. Tiglylglycine was absent. Genetic testing identified the compound heterozygosity for two pathogenic ACAT1 variants. The second patient showed increased levels of C5:1, C4DC/C5OH, C3DC/C4OH in the NBS. uOAs revealed 2-methyl-3-hydroxybutyrate and tiglylglycine. A homozygous VUS in ACAT1 was identified. The third case showed elevation of C4DC/C5OH, C3DC/C4OH in the NBS, with a slight increase in C5:1. uOAs showed 2-methyl-3-hydroxybutyrate and tiglylglycine. A homozygous missense VUS was identified in the ACAT1 gene. BKTD exhibited variable NBS biochemical phenotypes across the three cases. While C5OH and C5:1, the primary markers, were not consistently elevated in all our cases, C4OH strongly increased in all three. Our findings support the use of C4OH in a combined marker strategy to improve BKTD NBS.

Background: Newborn screening (NBS) is a preventive healthcare program aiming at identifying the inborn errors of metabolism (IEMs) in asymptomatic infants to reduce the risk of severe complications. The aim of this study was to report the first years (2016–2020) of the expanded NBS program in the Lombardy region, Italy. Methods: Dried blood spots were collected from newborns’ heels at 48–72 h after birth. FIA-MS/MS was performed to evaluate specific biochemical markers. Genetic confirmation was achieved via Sanger or NGS on newborns and reported to a clinical reference center (CRC). Results: A total of 343,507 newborns were tested; 1414/343,507 resulted as positive to NBS and were reported to the CRC. A total of 209 newborns were diagnosed with IEMs: 206 infants received a diagnosis of IEM through NBS, confirmed by genetic analysis; three neonates were not positive to NBS but were subsequentially diagnosed with IEMs. A total of 1208/343,507 were false positive cases. Twenty-seven types of IEMs were diagnosed in 209 patients: 111 newborns were affected by aminoacidemias, 11 by urea cycle disorders, 27 by organic acidemias, 34 by fatty acid oxidation disorders, and 26 by secondary conditions. Conclusions: We report here for the first time the IEM incidence and distribution in the Lombardy region in the first five years of NBS.