[Unexpected death of a two-year-old child: How electron microscopy helped to identify the potential cause]

A two-year-old child was found lifeless in bed after experiencing brief gastrointestinal symptoms.Histological examination revealed no abnormalities, but electron microscopy showed clear atypia of the mitochondria with linear paracrystalline inclusions.Genetic testing revealed variants of unclear significance in the TYMP and AIFM1 genes and a heterozygous pathogenic mutation in the GCDH gene.To date, no clear causality between the mutations found and the mitochondrial morphology can be established, but in vitro experiments show certain analogies to the structural changes in the mitochondria detected here.