Disorders of Purine and Pyrimidine metabolism

Immune dysfunction

________ appear to result from accumulation of dGTP and dATP, which allosterically inhibit ribonucleotide reductase, depleting cells from DNA precursors, especially dCTP.

Adenosine Deaminase function

________ irreversibly deaminates adenosine converting it to inosine.

Hypouricosuria

________: presence of an unusually low amount of uric acid in the urine.

uric acid concentration

Hypouricemia: serum ________ of less than 2.0 mg /dL.

Hypouricemia

serum uric acid concentration of less than 2.0 mg/dL

Hypouricosuria

presence of an unusually low amount of uric acid in the urine

Adenosine Deaminase (ADA) deficiency

affects T and B lymphocytes

Purine nucleoside phosphorylase (PNP) deficiency

Associated with an immunodeficiency involving T-cell function only, sparing B-cells.

dGTP and dATP

allosterically inhibit ribonucleotide reductase

Hypouricemia

rare condition due to severe deficiency of xanthine oxidase enzyme

xanthinuria

accumulation of hypoxanthine and xanthine

Hereditary orotic aciduria

results from a defect in de novo synthesis of pyrimidine nucleotides

defect in one or both of the activities of:

* $orotate phosphoribosyltransferase$
* $orotidine decarboxylase$

SCID

severe combined immunodeficiency disease

Hereditary orotic aciduria characterized by

* severe anemia


* growth retardation
* high levels of orotic acid excretion

Earliest symptoms of ADA deficiency:

* pneumonia
* chronic diarrhea
* widespread skin rashes
* development delay

ADA

Adenosine Deaminase

PNP

Purine nucleoside phosphorylase

PNP deficiency can cause

* Hypouricemia
* Hypouricosuria