Urinary excretion of purines, purine nucleosides, and pseudouridine in adenosine deaminase deficiency

Abstract

Previous studies on the urine composition of an adenosine deaminase deficient child have been extended. New analytical procedures have been developed for determination of adenine, deoxyadenosine and adenosine in urine. Of these compounds, deoxyadenosine was the major urinary component. After initiation of a red cell transfusion regimen as treatment for the child, a statistically significant reduction was noted in the excretion of deoxyadenosine and adenosine. Catabolic products (hypoxanthine, xanthine, uric acid) of the major purine bases, as well as excretory products (7-methylguanine, pseudouridine) of some of the minor bases found in nucleic acids, have also been determined by ion exchange analysis. A decrease in the excretion level of 7-methylguanine following initiation of red cell infusions suggested an effect of adenosine deaminase deficiency on nucleic acid methylation. We have discussed the role of adenosine deaminase in adenosylmethionine metabolic pathways and have reviewed the evidence suggesting that increased levels of adenosine might play a major role by altering nucleic acid methylation reactions, particularly those involving methylation of the guanine cap of messenger RNA. We have also contrasted purine excretory patterns of our adenosine deaminase-deficient child with excretory patterns noted by others in a child with purine nucleoside phosphorylase deficiency. Despite similarities in the clinical syndrome, marked differences in purine excretory patterns have been noted.