Metabolism of Some Amino Acids

Question 1

PKU

Answer 1

causes a buildup of toxic metabolites and starvation for tyrosine

Mental retardation is the primary problem

key feature: MOUSY ODOR

Question 2

treatment for PKU

Answer 2

Resistant to dietary reduction of dietary phenylalanine

L-DOPA, Folate and Tetrahydrobiopterine should be prescribed

Question 3

PKU diagnosis

Answer 3

Guthrie test

elevates phenylalanine levels

Question 4

MATERNAL PKU

Answer 4

Pregnant PKU patient has elevated phenylalanine

Placenta encourages higher phe in fetus

Question 5

HOMOCYSTINURIA

Answer 5

defect in cystathionine synthase, methionine synthanse, B12

accumulation of homocysteine

Manifestation:
Hypopigmentation 
Arachnodactylia 
Ectopia lentis 
Myopia
Faulty bone development
mental retardation

Question 6

amino acids causing maple syrup urine disease

Answer 6

accumulation of:
valine
leucine
isoleucine

Question 7

maple syrup urine disease

Answer 7

Deficiency of enzyme Alpha ketoacid decarboxylase / dehydrogenase (requires B1, B2, B3, B5, lipoic acid)

Manifestation:
Acidosis
mental retardation
convulsions
coma
Urine smells of burnt sugar (maple syrup)

Question 8

Alkaptonuria

Answer 8

deficiency in Homogentisate 1,2 - deoxygenase

Manifestation:
dark pigment in urine
late-developing arthritis

Question 9

Defect of what enzymes increases the catabolism of phenylalanine

Answer 9

Phenylalanine hydroxylase

Carbinoalamine dehydratase

DHB reductase

Question 10

METHYLMALONIC ACIDEMIA

Answer 10

Deficiency of enzyme methyl malonyl Co-A mutase

Dependent on B12

Accumulation of methylmalonic acid (Neurotoxin)

Manifestation:
vomiting
convulsions
mental retardation
early death