(A) Graphical overview of all variants in this study in relation to COQ8A protein structure and domains, including the mitochondrial targeting sequence (MTS), the transmembrane domain (TM), subdomains of the protein kinase-like (PKL) superfamily (PKL I-IX) as well as the UbiB family-specific N-terminal extension (NTE), N lobe insert (NLI), and C lobe insert (CLI). Numbers indicate variant IDs specified in Table 1, missense variants of unknown significance are marked in grey. (B) Missense variants in relation to specific sequence motifs. Bold titles and letters indicate functional motifs and conserved amino acids of the COQ8A active site, respectively. Variants cluster predominantly near structural or functional motifs, except for one cluster affecting a yet undefined region.