Background: Carnitine palmitoyltransferase I (CPT I ) is the enzyme taking part in transfer of long chain fatty acids whose deficit is manifested by recurrent, life threatening episodes of consciousness impairment and coma accompanied by hypoglycemia, hyperamonemia and increased activity of liver enzymes.Case Report: The authors discuss clinical picture and diagnostic difficulties connected with carnitine palmitoyltransferase I deficiency in a 7-year-old girl of no significant family history. Being the child of healthy, unrelated parents and having 23-year-old healthy sister, the girl was born with CIV (CI and CII spontaneous miscarriages) after regular course of pregnancy. Labour at term by caesarian section, birth weight -3100g, Apgar score-7. In the neonatal period hypoglycemia with cardio-respiratory distress of unknown etiology was observed while psychomotor development was normal in both neonatal and early childhood periods. At the 5th year of age after tonsillectomy the girl was affected by symptoms of abrupt metabolic crisis with hypoglycemia and liver failure. At the age of 7 the upper respiratory tract infections resulted in dramatic deterioration of the patient’s clinical status. Deeply unconscious and in coma she was diagnosed with CPT I deficiency in peripheral blood leukocytes and treated at the Intensive Care Unit.Conclusions:CPT I deficit is a rare disorder of childhood. It should however be considered in differential diagnosis of rapidly developing metabolic crises as early diagnosis allows for successful therapy, as well as for prophylaxis to minimize the risk of subsequent crisis.

Keywords: carnitine palmitoyltransferase, fatty acid beta-oxidation, Child