[The glucose-6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase ratio in the identification of glucose-6-phosphate dehydrogenase heterozygosity]. / Il rapporto G-6PD/6-PGD nella identificazione dell' eterozigosi per la G-6PD.

ABSTRACT

Deficiency in human G-6PD is a widespread X-linked disorder, which is mainly characterized by susceptibility to hemolytic anaemia after the ingestion of certain drugs or toxic substances (e.g. pyrimidine derivates contained in fava beans). G-6PD deficiency in hemizygous males in easily detectable since enzymatic activity is almost absent. In heterozygous subjects the determination of enzymatic activity on red cell lysate cannot detect a partial G-6PD deficiency. Cytochemical methods as methemoglobin reduction test or tetrazolium reduction test are more sensitive than spectrophotometric quantitative test, but are not suitable for screening purposes. We measured both G-6PD activity and 6-PGD activity in G-6PD heterozygous females and we evaluated the G-6PD/6PGD ratio. We tested this ratio also in thalassemic traits and in G-6PD heterozygotes with thalassemic trait in order to detect the interference of thalassemic pathology with the phenotypic expression of the gene for G-6PD. We found that the mean G-6PD values were statistically reduced in G-6PD heterozygous females; on the contrary the measurement of true G-6PD activity alone is not a good tool for discriminating heterozygous subjects with and without thalassemic trait. Actually 100% and 79% of values observed were in the normal range +/- 2 DS respectively. The mean G-6PD/6-PGD ratio in heterozygotes for G-6PD deficiency with and without thalassemic trait was lower than normal and the individual values of G-6PD/6-PGD ratio were in the normal range +/- 2 DS only in a few subjects (8.3% and 10.7% respectively).(ABSTRACT TRUNCATED AT 250 WORDS)