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Urate production in heterozygotes for glucose-6-phosphatase deficiency
Insights
Heterozygous parents of children with glucose-6-phosphatase deficiency do not exhibit abnormalities in urate or lipoprotein metabolism. Their urate production and excretion, along with key metabolic markers, remain within normal ranges.
Area of Science:
- Biochemistry
- Metabolic Disorders
- Genetics
Background:
- Glucose-6-phosphatase deficiency is a genetic disorder affecting glucose metabolism.
- Homozygous deficiency is associated with abnormalities in urate and lipoprotein metabolism.
- The role of partial deficiency and its metabolic consequences require further investigation.
Purpose of the Study:
- To investigate urate production and excretion in heterozygous parents of a child with glucose-6-phosphatase deficiency.
- To determine if partial glucose-6-phosphatase deficiency is associated with metabolic abnormalities.
- To assess erythrocyte phosphoribosyl-pyrophosphate concentration in heterozygotes and homozygotes.
Main Methods:
- Studied urate metabolism (pool, turnover, synthesis, renal clearance, excretion) in heterozygous parents.
- Measured serum cholesterol and triglyceride concentrations.
- Assessed erythrocyte phosphoribosyl-pyrophosphate concentration in a homozygote and a heterozygote.
Main Results:
- Heterozygotes showed normal urate pool, turnover, synthesis, renal clearance, and excretion.
- Serum cholesterol and triglyceride levels were normal in heterozygotes.
- Erythrocyte phosphoribosyl-pyrophosphate concentrations were normal in both homozygote and heterozygote.
Conclusions:
- Partial glucose-6-phosphatase deficiency is not linked to the urate and lipoprotein metabolism abnormalities seen in homozygous deficiency.
- Increased de novo purine biosynthesis in glucose-6-phosphatase deficiency is not explained by elevated erythrocyte phosphoribosyl-pyrophosphate concentration.
Abstract:
Urate production and excretion were studied in heterozygous parents of a child with glucose-6-phosphatase deficiency. Both parents demonstrated glucose-6-phosphatase concentrations in platelets intermediate between those in the homozygote and the normal. The miscible urate pool and turnover rate, the rate of incorporation of [14C]glycine into urate, the renal clearance of urate and the percentage excretion of labelled urate by the renal route were within the normal range in both heterozygotes, as were the serum cholesterol and triglyceride concentrations. Thus, a partial deficiency of glucose-6-phosphatase was not associated with the abnormalities of urate or lipoprotein metabolism which are features of homozygous glucose-6-phosphatase deficiency. Erythrocyte phosphoribosyl-pyrophosphate concentration, an increased concentration of which has been postulated as the mechanism responsible for the increased de novo purine biosynthesis in glucose-6-phosphatase deficiency, was found to be within the normal range in erythrocytes from both a homozygote and a heterozygote for this condition.