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Biochemistry

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Enzymes

Question
20 out of 79
 

Mousy odour urine is seen in



A Phenylketonuria

B Maple syrup urine disease

C Isovaleric aciduria

D None of the above

Ans. A Phenylketonuria

[A] Metabolic Disorder of phenylalanine catabolism

The major metabolic disorders associated with impaired ability to convert phenylalanine to tyrosine falls into three broad groups: -

a. Classic phenyl ketonuria or Type I - phenylalanemia : Defect in phenylalanine hydroxylase

b. Phenylalanemia Type II and III defect in dihydrobiopterin reductase

c. Type IV and V defect in dihydrobiopterin biosynthesis.

Catabolites phenyl acetate and others are excreted in urine and responsible for “Mousy odour”

C/F -

a. Mental Retardation (major problem)

b. Seizures, psychoses, Eczema, “ Mousy odor”

Diagnosis by

a. Guthrie’s test (Microbiological test in blood: phenylalanine is necessary for growth of bacillus subtilis)

b. 10% ferric chloride test — screening test — on fresh urine —i Emerald green colour.

c. Fluorometric assay

d. Dinitrophenylhydrazine yellow precipitate. with fresh or old urine.

- Prenatal diagnosis by Molecular probe. lit -

a. Diet restriction of phenylalanine but not completely

b. It is necessary for normal growth. And may be terminate by age 6 yrs.

c. Mental retardation can be prevented if diet restriction is initiated within few weeks after birth.

[B] Maple syrup urine disease (Branched chain Ketonuria)due to absence of &keto acid

decarboxylase, leads to defect in metabolism of Branch chain amino acid- leucine, isoleucine and valine (their level ‘ted in blood and plasma)

C/f

a. Maple syrup or Burnt sugar odour of urine

b. In this FeCl2 test — Gives Blue color. (Navy Blue colour)

[C] Isovaleric Acidemia - Also known as sweety foot syndrome due to deficiency of Isovaleryl Co-A dehydrogenase. C/F“Cheesy odor” of breath and body fluids.

Enzymes Flashcard List

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