Hypoxanthine-guanine phosphoribosyl transferase deficiency

Area of Science:

• Biochemistry
• Genetics
• Metabolic Disorders

Background:

• Congenital deficiency of hypoxanthine-guanine phosphoribosyl transferase (HG-PRT) is linked to the Lesch-Nyhan syndrome.
• HG-PRT deficiency exhibits significant molecular heterogeneity, with varying enzyme activity levels from zero to a few percent of normal.

Purpose of the Study:

• To explore the relationship between HG-PRT deficiency severity and clinical manifestations, including neurological dysfunction.
• To investigate the molecular basis and clinical spectrum of HG-PRT deficiency.

Main Methods:

• Analysis of enzyme activity in patients with HG-PRT deficiency.
• Clinical assessment of patients, including neurological evaluation.
• Molecular characterization of HG-PRT gene mutations.

Main Results:

• No consistent correlation observed between HG-PRT deficiency severity and clinical picture or neurological dysfunction.
• Individuals with undetectable HG-PRT activity but without Lesch-Nyhan syndrome have been identified.
• Partial HG-PRT deficiency presents with distinct clinical findings, sometimes including mild neurological abnormalities.
• Severe gouty arthritis and renal dysfunction are common due to uric acid overproduction in both complete and partial deficiency.
• Mutant HG-PRT enzymes show diverse kinetic and electrophoretic properties, indicating mutations in the structural gene.

Conclusions:

• HG-PRT deficiency profoundly disrupts purine interconversions.
• HG-PRT plays a crucial role in purine salvage, including the uptake of hypoxanthine and guanine.
• The uptake of inosine, guanosine, and adenosine also appears dependent on HG-PRT function.