Galactosemia / 한양의대학술지

Galactosemia, a term that denotes the presence of galactose in the blood, is the name of rare inborn error of galactose metabolism due to a deficiency of the enzyme galactokinase (GALK), galactose-1-phosphate uridyltransferase (GALT) and uridine diphosphate-galactose 4-epimerase (GALE). GALT deficiency is the most common and shows the most severe clinical manifestation, including hepatomegaly, cataracts, and mental retardation. The main symptom of GALT deficiency is juvenile cataracts. GALE deficiency has two different forms; benign and severe forms. The benign form has no clinical significance, however, the severe form shows the same clinical manifestations as those of GALT deficiency.

Galactosemia Detected by Neonatal Screening Test

PURPOSE: The genetic disturbance of galactosemia is expressed as a cellular deficiency of either galactose-1-phosphate uridyltransferase(GALT) or galactokinase(GALK) or UDP galactose 4-epimerase(GALE). To find-out the pattern of galactosemia in Korea, we retrospectively analyzed cases of galactosemia detected by neonatal screening program. METHODS: We analyzed medical records of patients who visited Soonchunhyang University Hospital at age of 1 month after showing abnormalities in neonatal screening of galactosemia. For accurate diagnosis, galactose was measured by enzyme immunoassay(EIA) and fluorophotometer, also galactose-1-phosphate by fluorophotometer. Enzyme activities of GALK, GALT and GALE in RBC and galactose-1-phosphate were measured by radioisotope assay(RIA). Beutler test were done. Patients went on a lactose-free diet and follow-up tests for galactose, galactose-1-phosphate level and enzyme activity were performed. RESULTS: 10 patients(male : 6, female : 4) were diagnosed as galactosemia. Two patients had GALK deficiency and two had GALT deficiency. Six were GALE deficient showing the largest number. In two patients with GALK deficiency, GALT and GALE activities were normal but GALK activities showed respectively reduced activity. For GALT deficiency, two patients had low GALT activity in RBC and showed genotype of Duarte 2/G(galactosemia) in DNA analysis. In one patient, GALT activity was normal. Three patients seemed to be heterozygote state of GALE deficiency according to GALE activity levels. Four patients showed GALK hyperactivity. CONCLUSION: GALE deficiency provided the highest number. After lactose-free diet, galactose and galactose-1-phosphate were normaly maintained. Neonatal screening on galactosemia is essential for preventing life-threatening symptoms and an accurate diagnosis is needed for finding out the type of galactosemia which is important for prognosis.

A presença da Galactoquinase em Tecidos Animais

The author relates experimental work which lead him to conclude for the presence of galactokinase in animal tissues, explaining in this way that the first step of the galactose intermediary metabolism is its esterification, in the presence of ATP and the enzyme in question, activated by magnesium to galactose-1-phosphate.

O autor relata trabalhos experimentais que o levaram a concluir pela existência da galactoquinase em tecidos animais, explicando desta maneira, que a primeira fase do metabolismo intermediário da galactose nos mesmos é a sua esterificação, em presença do ATP e da enzima em questão, ativada pelo magnésio, para galactose-1-fosfato.