A successful trial of enzyme replacement therapy in a case of argininemia.

A 5-year-old boy with severe mental retardation and spastic quadriplegia accompanied by tonic seizures and hyperammonemia was diagnosed as having argininemia due to an arginase deficiency in his erythrocytes. His motor and mental abilities began to deteriorate at the age of 3 years. Thereafter, he lost his ability to stand alone, to sit and even to crawl by himself. After he was diagnosed as argininemia , a protein restricted diet was given as therapy, which was accompanied with a supplement of essential amino acids. However, his clinical condition had not improved very much. The erythrocytes in a normal person was found to have the ability to decrease the patient's elevated plasma arginine level to normal when they are mixed in vitro. First we tried replacing his red cells by a blood transfusion. Then we replaced them with the aid of an IBM 2997 blood cell separator. Following this his clinical and biochemical condition improved, and as a result so did his sitting and crawling abilities. It appears that the replacement of red blood cells improves not only the clinical and biochemical conditions, but the general condition of the patient as well.