{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:12:57Z","timestamp":1760058777216,"version":"build-2065373602"},"reference-count":34,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2025,4,30]],"date-time":"2025-04-30T00:00:00Z","timestamp":1745971200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Italian Ministry of Health","award":["RC 13\/24","RC 10\/24"],"award-info":[{"award-number":["RC 13\/24","RC 10\/24"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Genes"],"abstract":"<jats:p>Background: Very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD) is caused by biallelic pathogenic variants in ACADVL (acyl-CoA dehydrogenase very-long-chain), leading to impaired fatty acid oxidation and the accumulation of long-chain acylcarnitine. We report a single case of a two-year-old girl, whose neonatal metabolic screening revealed an acylcarnitine profile suggestive of VLCADD, with residual enzymatic activity of 19.8%. Methods: We performed ACADVL whole-gene sequencing. We then carried out an in silico analysis of the potential effects of the variants with dedicated tools, assessing splicing, RNA structure, RNA binding factors, and protein structure. We also conducted gene expression analysis. Results: Genetic testing identified her as compound heterozygous for the pathogenic ACADVL variant (NM_000018.3):c.848T&gt;C, inherited from her mother, and for the two paternal variants, c.-64T&gt;C in the basal promoter and c.957G&gt;A, a synonymous substitution in exon 10. Gene expression analysis revealed reduced ACADVL mRNA levels in the proband\u2019s blood cells but without abnormal isoform production. A decreased expression of the paternal allele carrying the 957A was also observed. Despite this significant reduction in mRNA levels, the underlying mechanism remains unclear. Conclusions: Although currently healthy, due to the VLCAD residual activity within the range associated with the mild form of the disease, the child might be at potential risk for metabolic decompensation or late-onset VLCADD. Our results indicated an allelic imbalance in mRNA expression and c.957G&gt;A is identified as a hypomorphic allele. This suggests that deep ACADVL sequencing is a valuable tool for correlating genetic variants with enzymatic activity levels.<\/jats:p>","DOI":"10.3390\/genes16050538","type":"journal-article","created":{"date-parts":[[2025,5,1]],"date-time":"2025-05-01T03:50:43Z","timestamp":1746071443000},"page":"538","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["ACADVL Deep Sequencing in a Case Study: Beyond the Common c.848T&gt;C Pathogenic Variant"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7523-3154","authenticated-orcid":false,"given":"Francesco","family":"Baldo","sequence":"first","affiliation":[{"name":"Institute for Maternal and Child Health IRCCS Burlo Garofolo, 34137 Trieste, Italy"},{"name":"Department of Medicine, Surgery and Health Sciences, University of Trieste, 34100 Trieste, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5886-9129","authenticated-orcid":false,"given":"Luisa","family":"Zupin","sequence":"additional","affiliation":[{"name":"Institute for Maternal and Child Health IRCCS Burlo Garofolo, 34137 Trieste, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5099-6526","authenticated-orcid":false,"given":"Andrea","family":"Magnolato","sequence":"additional","affiliation":[{"name":"Institute for Maternal and Child Health IRCCS Burlo Garofolo, 34137 Trieste, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0110-5942","authenticated-orcid":false,"given":"Valeria","family":"Capaci","sequence":"additional","affiliation":[{"name":"Institute for Maternal and Child Health IRCCS Burlo Garofolo, 34137 Trieste, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8024-0482","authenticated-orcid":false,"given":"Maria Teresa","family":"Bonati","sequence":"additional","affiliation":[{"name":"Institute for Maternal and Child Health IRCCS Burlo Garofolo, 34137 Trieste, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,4,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"556","DOI":"10.1038\/s41431-018-0330-0","article-title":"Value of Genetic Analysis for Confirming Inborn Errors of Metabolism Detected through the Spanish Neonatal Screening Program","volume":"27","author":"Navarrete","year":"2019","journal-title":"Eur. 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