Nitrogen Metabolism

Question 1

In hereditary hyperammonemia, what is the COMMON enzyme deficient?

Answer 1

Ornithine transcarbomylase

Question 2

In hereditary hyperammonemia, what is the most SEVERE deficiency?

Answer 2

CPS-1 deficiency

Question 3

Treatment for hereditary hyperammonemia?

Answer 3

Phenylbutyrate

Question 4

2 reasons for phenylketonuria?

Answer 4

1) decreased phenylalanine hydroxylase; 2) decreases tetrahydrobiopterin

Question 5

Clinical presentation of phenylketonuria?

Answer 5

accumulation of phenylketones, severe mental retardation, fair skin and eczema, musty body odor

Question 6

What is deficient in alkaptonuria?

Answer 6

homogentisate oxidase

Question 7

What are the clinical presentation of alkaptonuria?

Answer 7

alkapton bodies ( turn to black urine), ochronosis, debilitating arthralgia, oslers sign

Question 8

What is deficient in albinism?

Answer 8

copper, requiring tyrosinase due to lack of tyrosinase transporters

Question 9

what disease has defect in methionine degradation?

Answer 9

homocystinuria

Question 10

What is an important clinical presentation of homocystinuria?

Answer 10

Stroke in the children and young adults

Question 11

Homocysteine needs which 2 B vitamins?

Answer 11

B6 (cysteine) and B12 (methionine)

Question 12

This is an inherent defect of renal tubular amino acid transporter for cysteine, ornithine, lysine and arginine in the PCT of the kidneys

Answer 12

Cystinuria

Question 13

What is the clinical presentation of cystinuria?

Answer 13

staghorn calculi

Question 14

what are the 4 amino acids involved in methylmalonyl coa mutase deficiency?

Answer 14

isoleucine, valine, threonine, methionine

Question 15

Maple Syrup Urine Disease is deficiency in what enzyme?

Answer 15

alpha ketoacid dehydrogenase complex

Question 16

What are the 3 branched amino acids involved in MSUD?

Answer 16

isoleucine, leucine, valine

Question 17

Where is heme synthesis done?

Answer 17

mitochondria and cytoplasm

Question 18

What is the rate limiting step of heme synthesis?

Answer 18

Glycine+Succinyl CoA -> Aminolevulinic acid ( ALA synthase)

Question 19

What step in heme synthesis is inhibited by heavy metal ions that replace zinc?

Answer 19

Formation of porphobilinogen

Question 20

What is the enzyme used in enhancing formation of heme?

Answer 20

Ferrochelatase

Question 21

What enzyme is needed for the conjugation of bilirubin to two molecules of glucoronic acid?

Answer 21

Bilirubin glucoronyltransferase

Question 22

What 2 enzymes are inactivated by lead in lead poisoning?

Answer 22

ALA dehydratase and ferrochelatase

Question 23

what is the description of RBC in lead poisoning?

Answer 23

microcytic, hypochromic anemia with basophilic stippling of RBC

Question 24

Most common porphyria disorder?

Answer 24

porphyria cutanea tarda

Question 25

Clinical Presentation of Porphyria Cutanea Tarda

Answer 25

Photosensitivity, Neuropsychitric sypmtoms, abdominal pain