Lysine Intolerance With Periodic Ammonia Intoxication

SUFFERING from lysine intolerance, the girl was first observed at the age of 3 months. She showed vomiting; episodes of coma, starting shortly after birth; seizures; and a variable muscular tonicity.¹ During these comatose states the concentration of blood ammonia would rise up to 500μg/100 ml and 560μg/100 ml. The rise of ammonia as well as that of urea nitrogen was directly proportional to the protein ingested. On a low protein intake of 1.5 gm/kg/day the child remained well. The concentration of plasma amino acids was then within the normal range. When the protein intake was increased to 3 gm/kg/day or transitory to 6 gm/kg/day, a rise in blood ammonia was observed (Fig 1). The child became restless, started to vomit, developed a considerable rigidity of the muscles, became apathetic, and comatose. During these periods of high protein intake the concentration of lysine in the plasma rose from 2.7