FBXL4 and mitochondrial disease: Twenty-five of the 85 patients received a confirmed genetic diagnosis via the clinical exome panel, with the following affected genes: FBXL4 (n = 4), AARS2 (n = 2), ELAC2 (n = 2), LRPPRC (n = 2), C12orf65, CA5A, CACNA1A, EARS2, EXOSC3, FOXRED1, GRIN2A, IBA57, LAMA2, MMAB, NDUFB11, PDHA1, RMND1, SDHA, and VPS13B (all n = 1; underlined genes are not considered mitochondrial disease genes and were identified via additional panel analysis) (table 1).