95 Simple screening methods for disorders of purine metabolism using dried blood and/or urine spots on filter paper

Abstract

Hypoxanthine-guanine phosphoribosyltransferase(HGPRT) and adenine phosphoribosyltransferase(APRT) function in the metabolic salvage of pruines. Although these enzyme deficiencies are extremely rare, an early diagnosis is required to prevent renal damage. Therefore simple methods for the detection of HGPRT and/or APRT deficiencies using dried filter paper blood and/or urine spots were studied. Enzyme activity in the eluate from dried filter paper blood spots stored for 4 weeks at room temperature were shown to be quite stable. DE-81 paper allows immobilization of the nucleotides, while removing purine bases by washing. Autoradiography prepared from dried filter paper blood spots and DE-81 paper soaked with enzyme reaction mixtures containing 14C-hypoxanthine and/or 14C-adeninc showed sharp radioactive spots in normal subjects. No activity was seen in the case of the Lesch-Nyhan syndrome and/or APRT deficiency. The concentration of uric acid, creatinine and 2, 8-dihydroxyadenine (2, 8-DHA) in the eluates from dried filter paper urine spots were also shown to be measurable. The higli ratio of uric acid to creatinine and/or the demonstration of 2, 8-DHA in these eluates was also useful for the screening of HGPRT and/or APRT deficiencies. This method is very convenient for sample collection and simplifies the transfer of samples.