Simple heterozygous mutations in ETFA may be significant, since such mutations in ACAD cause adult onset disease.24 The patient's ETFA mutation encodes a T171I substitution, which decreases thermal stability of the protein, and is over‐represented in patients with the hyperammonemia‐associated disease of very‐long‐chain acyl‐CoA dehydrogenase deficiency.25 This evidence concerns the gene ETFA and Hyperammonemia.