Genetic Disorders Of Metabolic Pathways

Question 1

What amino acid metabolism is defective in phenylketonuria?

Answer 1

Tyrosine which interferes with melanin

Question 2

What enzyme is defective in Phenylketonuria?

Answer 2

Phenylalanine hydroxylase (phenylalanine to tyrosine)

Question 3

What coenzyme is needed for the production from phenylalanine to tyrosine?

Answer 3

Tetrahydrobiopterin (BH4) - secondary

Question 4

What is the enzyme needed for the recycling of BH4?

Answer 4

Dihydropteridine reductase

Question 5

What alternate metabolite of phenylketonuria producing the musty smell of urine?

Answer 5

Phenylacetate

Question 6

What alternate metabolite of phenylketonuria interferes with transfer of pyruvate into mitochondria?

Answer 6

Phenyl pyruvate

Question 7

What can be used as treatment for secondary PKU?

Answer 7

Sepiapterin

Question 8

What are the Lab tests used to test for Phenylalanine levels in the blood?

Answer 8

Guthrie test and MS/MS

Question 9

Alkaptonuria is a defect in the metabolism of what?

Answer 9

Tyrosine

Question 10

Alkaptonuria is a deficiency in what enzyme in the tyrosine metabolic pathway?

Answer 10

Homogentisate oxidase

Question 11

What does Alkaptonuria typically present with?

Answer 11

Ochronosis (discoloration of sclera)

Dark colored urine

Question 12

Albinism is a defect in what enzyme?

Answer 12

Tyrosinase (unable to synthesize melanin)

Question 13

Tyrosinemia Type 1 is a defect in what enzyme?

Answer 13

Fumarylacetoacetate hydrolase

Question 14

What is the toxic alternate metabolite that builds up in Tyrosinemia type I?

Answer 14

Succinylacetone

Question 15

What enzyme is deficient in classic homocytinuria?

Answer 15

Cystathionine Beta-synthase

Question 16

What builds up in the alternate pathway when someone has homocystinuria?

Answer 16

Homocysteine thiolacetone

Question 17

Clinical manifestation of homocystinuria?

Answer 17

• Marfan-like habitus
• intellecual disability
• joint contractures

Question 18

Maple syrup urine disease is a defect in the metabolism of what?

Answer 18

BCAAs

Question 19

What is a hallmark of galactosemia?

Answer 19

Cataracts

Question 20

Maple syrup urine disease is a defect in what enzyme?

Answer 20

Alpha ketoacid decarboxylase

Question 21

What is the hallmark of phenylketonuria?

Answer 21

Severe intellectual disability: IQ