An inborn error of ketone body catabolism resulting in
intermittent episodes of ketoacidosis.
SCOT Deficiency; Succinyl-CoA:3-Oxoacid-CoA Transferase
Deficiency; Succinyl-CoA: Ketoacid-CoA Transferase
Deficiency; Succinyl-CoA:Acetoacetate Transferase Deficiency.
Less than 25 cases have been reported in the literature.
Autosomal recessive. Gene map location is
chromosome 5p12-p13. Prenatal diagnosis can be made because cultured
amniocytes have measurable succinyl-CoA:3-ketoacid CoA transferase (SCOT)
SCOT, the key enzyme of ketone body utilization, is an extrahepatic mitochondrial matrix
enzyme necessary for synthesis of acetoacetyl-CoA by transfer of a CoA
moiety from succinyl-CoA to acetoacetate. Ketoacidosis is caused by SCOT
deficiency resulting in reduced ketone body utilization.
Laboratory findings include succinyl-CoA:3-ketoacid-CoA
transferase deficiency, together with ketonuria. Normal levels of plasma
amino acids, lactic acid, ammonia, glucose, and organic acids other than
beta-hydroxybutyrate and acetoacetate.
Severe intermittent ketoacidosis in ketogenic
situations (fasting, febrile illness, any cause of stress) with no symptoms
between episodes. There is persistent ketonuria, even in
postprandial times. Age of onset is variable; however, a neonatal onset is
common. The main clinical symptoms are vomiting and tachypnea.
Need to exclude diabetes mellitus
and type I glycogen storage disease. Ensure adequate fluid resuscitation and
treatment. Treatment consists of limiting protein intake, providing adequate
calorie intake, and preventing aggravation of ketosis by providing alkaline therapy
at the onset of any intercurrent infection. Check blood glucose,
electrolyte levels, and blood gases with acid-base status.
Risk of pulmonary aspiration during
induction of anesthesia is increased. Maintain adequate hydration. Close
monitoring of blood gases in the perioperative period is required.
No known specific pharmacological
implications with this condition.
Infections may exacerbate ketoacidosis further.
The threshold to use antibiotics should therefore be low.
Other constitutional causes of
ketosis in children (differential diagnosis is made by enzyme assay), namely
Ketotic Hypoglycemia: Unclear disorder associating ketosis and
hypoglycemia; there is a carbohydrate deprivation with dependence on adipose
tissue as sources of energy.
Mitochondrial Acetoacetyl-CoA Thiolase (ACAT) Deficiency: Autosomal
recessive disorder of isoleucine and ketone body metabolism characterized by
recurrent episodes of metabolic acidosis, hypoglycemia, lethargy, and
coma as a consequence of the defective mitochondrial enzyme acetoacetyl-CoA
thiolase that allows conversion of fat to energy (especially in fasted
Snyderman SE, Sansaricq C, Middleton B: Succinyl CoA:3-ketoacid CoA
transferase deficiency. Pediatrics