PDC and pyruvate dehydrogenase E3 deficiency: Functional analyses, including RNA sequencing, immunofluorescence microscopy, and PDC activity, were hence performed due to high clinical suspicion for DLDD, revealing a monoallelic transcription of the DLD gene, reduced protein expression of DLD, and reduced PDC activity in the patient's fibroblasts, thus confirming the diagnosis of DLDD (see Figure S1).