HADHA and hyperinsulinemic hypoglycemia, familial, 4: Genetic mutations in enzymes involved in fatty acid oxidation pathways, such as trifunctional enzyme subunit α (HADHA), trifunctional enzyme subunit β (HADHB), or long-chain 3-hydroxyacyl-CoA dehydrogenase, cause trifunctional protein deficiency, and mitochondrial deficiency, leading to pigmentary retinopathies and vision loss (63, 64).