Blom et al. (1981) reported a newborn girl with hypotonic myopathy, severe brain damage, and poor growth. On a carbohydrate-rich diet, she had urinary excretion of hexanoic acid, including 2-ethyl-3-keto-hexanoic acid, 2-ethyl-3-hydroxy-hexanoic acid, and 2-ethyl-hexanedioic acid. Liver biopsy ... Blom et al. (1981) reported a newborn girl with hypotonic myopathy, severe brain damage, and poor growth. On a carbohydrate-rich diet, she had urinary excretion of hexanoic acid, including 2-ethyl-3-keto-hexanoic acid, 2-ethyl-3-hydroxy-hexanoic acid, and 2-ethyl-hexanedioic acid. Liver biopsy showed deficient activity of acetyl-CoA carboxylase (ACACA; 200350); fibroblasts showed about 10% of normal activity. Blom et al. (1981) concluded that the patient had an inborn error of de novo fatty acid synthesis.