0521779407-17 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:19
1254 Purine and Pyrimidine DisordersConfirmatory Tests
■increased urine hypoxanthine (HPRT def., PRPS superactivity)
■increased urine adenine 2,8-dihydroxy-adenosine (APRT def.)
■increased urine, plasma, CSF succinyl-aminoimidazole carboxam-
ide riboside (ASL def.)
■increased blood and urine hypoxanthine, xanthine (XDH def.)
■increased erythrocyte dATP (ADA def.)
■increased urine 2’-deoxyadeosine (ADA def.)
■increased plasma inosine, guanosine, deoxyinosine, deoxyguano-
sine (PNP def.)
■increased urine uracil, thymine (DHPD, DHPA defs.)
■increased urine dihydrothymine, dihydrouracil (DHPA def.)
■increased urine beta-ureidoisobutyrate (Ureidopropionase def.)
Other Tests
■erythrocyte enzymology (HPRT, APRT, ADA, PNP, UMPS, UMPH1
defs., PRPS superactivity)
■liver biopsy enzymology (XDH def.)
■DNA analysis may be available in some centers
■prenatal diagnosis using enzymology or DNA analysis may be avail-
able in some centers
Imaging
■abdominal ultrasound: not diagnostic, may detect lithiasis (HPRT,
APRT, XDH defs., PRPS superactivity), obstructive uropathy (UMPS
def.), or splenomegaly (UMPH1 def.)
differential diagnosis
■gout
■other causes of renal failure/lithiasis
■other causes of immunodeficiency (AIDS, inherited disorders of T-/
B-cell dysfunction)
■increased orotic acid is also seen in urea cycle defects (esp. ornithine
transcarbamylase def.)
■self-injurious behavior may be seen in familial dysautonomia,
Smith-Magenis syndrome, de Lange syndrome
■XDH deficiency may be part of molybdenum cofactor deficiency
(combined XDH/sulfite oxidase deficiencies)
management
What to Do First
■assess severity of immunologic, neurologic, renal and joint disease
■treat anemia