Page 102 - General Biochemistry

• Adenine phosphoribosyl transferase (APRT)

Adenine + PRPP AMP + PPi

• Hypoxanthine-Guanine phosphoribosyl transferase (HGPRT) (HPRT)

Hypoxanthine + PRPP IMP + PPi

Guanine + PRPP GMP + PPi

Lesch-Nyhan Syndrome

A disease caused by defect in production or activity of HPRT leading to

increased level of:

1) Hypoxanthine and Guanine ( in degradation to uric acid) i.e increase uric
acid production

1) PRPP thus stimulating the production of purine nucleotides (and thereby
increases their degradation)

Symptoms: neurological manifestations (cognitive and attention deficit
behavior) whose severity depends on the degree of the enzymatic deficiency

Purine Autism

• 20% of autistic population have increased de novo purine synthesis
• To diagnose them we must test urine over 24 hours
Urine specimen in infancy should be obtained, but it’s difficult to do, So we can

know from the Pink urine due to uric acid crystals that may be seen in
diapers

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