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In an optimalised radiochemical procedure for simultaneous measurement of hypoxanthine‐guanine phosphoribosyl transferase (HG‐PRT) and adenine phosphoribosyl transferase (A‐PRT) from individual human hair roots, the HG‐PRTIA‐PRT activity ratio was used as an index for heterozygote detection in the Lesch‐Nyhan syndrome. Hair roots of female carriers of HG‐PRT deficiency could be distinguished from those of normal and mutant individuals. Evidence is presented that temperature at which hair roots are frozen prior to the enzyme assays affects the HG‐PRTIA‐PRT activity ratio The ratio tends to be higher after lower freezing temperatures.

In man congential lack of enzyme of the purine salvage system, hypoxanthineguanine phosphoribosyl transferase (HG-PRT E.C. 2.4.2.8), is mostly accompanied by a picture known as the Lesch-Nyhan snydrome. The degree of deficiency may vary from zero to a few percent of normal activity but a correlation between the severity of HG-PRT deficiency and the clinical picture has not been observed, no more than a correlation HG-PRT deficiency and neurological dysfunction. But individuals with undetectable HG-PRT activity but without the Lesch-Nyhan syndrome have been described. Patients with partial HG-PRT defiency have clinically distinctive findings. Sometimes mild neurological abnormalities are observed. Because of marked overproduction of ric acid severe gouty arthritis and renal dysfunction are often encountered in both complete and partial deficiency. There is considerable molecular heterogeneity in HG-PRT deficiency in man. Mutant ebnzymes may exhibit different kinetic and electrophoretic properties, indicating that hterwe might be a mutation on the structural gene coding for HG-PRT. Lack of HG-PRT disturbs purine interconversions profoundly. In addition to an important function of HG-PRT in the uptake of the purine hypoxantine and guanine into the cell, the effective uptake of inosine, guanosine and adenosine also seems to be dependent on HG-PRT...

Kinetic properties of human hair root glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were studied in order to optimize the assay of these enzymes in lysates from single hair roots. In contrast to previously reported methods, an excess of purified 6-phosphogluconate dehydrogenase was added to the glucose-6-phosphate dehydrogenase reaction mixtures, thus allowing a more exact quantification of glucose-6-phosphate dehydrogenase activity. Although enzyme histochemical techniques suggest a similar distribution of hair root glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, enzyme assays on hair root segments after microdissection nevertheless indicate differences in the distribution of these enzymes. Upon storage a gradual drop in the activity of both hair root enzymes was found, but the rate of decrease in enzyme activity was about equal: the enzyme activity ratio was, therefore, not affected. This opens interesting possibilities for mailing hair roots for screening purposes without any special precautions.Glucose-6-phosphatdehydrogenase-Mangel: Biochemische und histologische Untersuchungen an Haarwurzeln zum Überträger-Nachweis

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