Identification and quantitation of adenine deoxynucleotides in erythrocytes of a patient with adenosine deaminase deficiency and severe combined immunodeficiency.

Deoxyadenosine 5’-triphosphate and deoxyadenosine 5’diphosphate are the most abundant nucleotides in erythrocytes of an untreated child with adenosine deaminase deficiency and severe combined immunodeficiency disease. Since ATP and ADP are the predominant nucleotides in normal erythrocytes and the deoxynucleotides are virtually absent, the high levels of dATP and dADP represent a major perturbation of the normal nucleotide pool. Levels of adenine nucleotides present in erythrocytes from the affected child, as quantitated by high pressure liquid chromatography, are: ATP, 91; dATP, 157; ADP, 22; and dADP, 27 nmol/109 cells. Deoxyadenosine 5’4riphosphate and deoxyadenosine 5’-diphosphate were unequivocally identified by enzymatic shift experiments, substrate replacement in a DNA polymerase assay and gas chromatography-mass spectrometry. The ratios of ATP to dATP and of ADP to dADP were 0.52 and 0.82, respectively. Total adenine nucleotide content of erythrocytes deficient in adenosine deaminase was about twice the level found in normal erythrocytes. Parents of the affected child had abnormally low levels of adenosine deaminase activity but had normal concentrations of adenine nucleotides in their erythrocytes. The adenosine deaminase activity in the affected child had a normal apparent K,,l for adenosine and normal electrophoretie mobility, but abnormal heat lability. This observation of abnormal deoxynucleotide metabolism suggests interference with DNA synthesis as a new explanation of the