[Clinical studies of histidinemia (author's transl)]

This study was performed to investigate 1) technical modification of Guthrie method for mass screening to detect histidinemia, 2) patients with histidinemia in view of genetic and biochemical aspects, and 3) therapy of histidinemia in newborn infants. Guthrie method was the useful method for mass screening of histidinemia in newborn infants. It is possible to measure blood level of histidine using by Subutilis spore ATTCC 6633 instead of ATCC 6051. Mass screening of histidinemia was done in about 20,000 newborn infants in Hokkaido, and one case of histidinemia, which was first case in Japan found by this method, was observed. In a case of 5 year-old boy with clinical histidinemia, in whom serum histidine level was 12.1 mg/kl, histidase activity of stratum corneum was not detectable, FIGLU and urocanic acid in urine and urocanic acid in sweat were not detected, the half life of histidine at intravenous histidine loading test was too long to measure. But in other case of 13 year-old boy without clinical signs of histidinemia, elder brother of former case, serum histidine level was 4.7 mg/dl, histidase activity was 11% of normal control, excretion of FIGLU and urocanic acid in urine, and urocanic acid in sweat were observed, and the half life of histidine was 5 hours and 50 minutes (normal: 2 hours and 20 minutes). In both cases, Tryptophan absorption and metabolism were not influenced by high level of blood histidine. Therapy with low histidine milk was made in 3 cases of affected infants. When histidine was given orally in dose of 30-35 mg/kg/day, serum histidine level was down to 3-5 mg/dl in a week in all cases, but in one case low proteinemia an anemia were observed. When histidine was orally given in a dose of 40-50 mg/kg/day, serum histidine level was well controlled. In all cases with histidine limited diets, mental retardation and growth retardation were not found.