Sudden death of a four-day-old newborn due to mitochondrial trifunctional protein/long-chain 3-hydroxyacyl-coa dehydrogenase deficiencies and a systematic literature review of early deaths of neonates with fatty acid oxidation disordersDrole Torkar, Ana (Avtor) Klinc, Ana (Avtor) Remec, Žiga Iztok (Avtor) Ranković, Branislava (Avtor) Bartolj, Klara (Avtor) Bertok, Sara (Avtor) Colja, Sara (Avtor) Čuk, Vanja (Avtor) Debeljak, Maruša (Avtor) Kozjek, Eva (Avtor) Repič-Lampret, Barbka (Avtor) Mlinarič, Matej (Avtor) Mohar Hajnšek, Tinka (Avtor) Perko, Daša (Avtor) Štajer, Katarina (Avtor) Tesovnik, Tine (Avtor) Trampuž, Domen (Avtor) Ulaga, Blanka (Avtor) Kovač, Jernej (Avtor) Battelino, Tadej (Avtor) Žerjav-Tanšek, Mojca (Avtor) Grošelj, Urh (Avtor) FAODLCHAD deficiencyLCHADDMTP deficiencyMTPDNBSfatty acid oxidation disordernewbornnewborn screeningsudden infant deathMitochondrial trifunctional protein (MTP) and long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiencies have been a part of the Slovenian newborn screening (NBS) program since 2018. We describe a case of early lethal presentation of MTPD/LCHADD in a term newborn. The girl was born after an uneventful pregnancy and delivery, and she was discharged home at the age of 3 days, appearing well. At the age of 4 days, she was found without signs of life. Resuscitation was not successful. The NBS test performed using tandem mass spectrometry (MS/MS) showed a positive screen for MTPD/LCHADD. Genetic analysis performed on a dried blood spot (DBS) sample identified two heterozygous variants in the HADHA gene: a nucleotide duplication introducing a premature termination codon (p.Arg205Ter) and a nucleotide substitution (p.Glu510Gln). Post-mortem studies showed massive macro-vesicular fat accumulation in the liver and, to a smaller extent, in the heart, consistent with MTPD/LCHADD. A neonatal acute cardiac presentation resulting in demise was suspected. We conducted a systematic literature review of early neonatal deaths within 14 days postpartum attributed to confirmed fatty acid oxidation disorders (FAODs), which are estimated to account for 5% of sudden infant deaths. We discuss the pitfalls of the NBS for MTPD/LCHADD.20252025-12-11 08:46:01Neznano24664sl