Urea/Nitrogen Metabolism

Question 1

Type 1 Hyperammonemia

Answer 1

No CPS
Lethargy, vomiting, hypothermia, fatal
Tx w/ Arginine

Question 2

Type 2 Hyperammonemia

Answer 2

NO OTC (most common)
Ammonia toxicity
Tx w/ low protein diet, ammonia detox (sodium benzoate, phenylacetate)

Question 3

N-Acetylglutamate Syn. Deficiency

Answer 3

No N-Ac. Synthase
Ammonia toxicity, COMA, ataxia, high ornithine
Tx w/ Carbamoyl Glutamate

Question 4

Citrullinemia

Answer 4

No Arginosuccinate synthase
Vomit, lethargy, ataxia, SZ
–Na Benzoate, Phenylacetate

Question 5

Arginosuccinic aciduria

Answer 5

No arginosuccinate lyase
vomit, lethargy, ataxia, sz AND Arginiosuccinase in CSF, Plasma
–Na benzoate, Na phenylacetate

Question 6

HGPRT

Answer 6

Adds ribose + phosphate to Purine

No HGPRT= Hyperuricemia, gout

Question 7

Xanthine Oxidase

Answer 7

Converts Hypoxanthine –> Xanthine
& Xanthine –> Uric Acid
Critical in formation, targeted by Allopurinol in Gout tx

Question 8

Lesch-Nyhan Syndrome

Answer 8

X linked, NO HGPRT
self-mutilation, mental retardation
Fatal due to kidney failure

Question 9

Adenylate kinase (myokinase)

Answer 9

2 ADP –> ATP + AMP

Needed in Purine salvage pathway since 4 ATP required and used up fast

Question 10

Gout

Answer 10

Uric acid crystals in joints esp. big toe
causes- too much PRPP, purines,
not enough HGPRT, no negative feedback

Question 11

Allopurinol

Answer 11

Gout tx; suicide inhibitor of Xanthine oxidase

Question 12

Congenital Nephrotic Syndrome

Answer 12

Massive proteinuria, albuminemia due to deficient nephrin (primary protein for slit diaphragms)
tx w/ ACE Inh/dialysis until transplant acquired
COL4A3 gene

Question 13

Pierson Syndrome

Answer 13

Defective laminin of BM, nephrotic syndrome + ocular and hearing abnormalities
LAMB2 gene