Biochemistry: Diseases Flashcards
Fructose in urine and blood, otherwise asymptomatic
Essential fructosuria
What enzyme is deficient in essential fructosuria?
Fructokinase
Hypoglycemia, jaundice, cirrhosis, and vomiting following consumption of fruit, juice or honey with reducing sugar in the urine
Fructose intolerance
What enzyme is deficient in fructose intolerance?
Aldolase B
How do you treat fructose intolerance?
Decrease intake of fructose and sucrose (glucose+fructose)
What is the pathophysiology of fructose intolerance?
Fructose -1P builds up, decreasing available phosphate so glycogenolysis and gluconeogenesis cannot occur
Galactose in blood and urine, infantile cataracts
Galactokinase deficiency, very mild
Failure to thrive, jaundice, hepatomegaly, infantile cataracts, MR
Classic galactosemia
What enzyme is deficient in classic galactosemia?
Uridyltransferase
What is the role of aldose reductase?
Provides an alternate means of trapping glucose in the cell, converts it to sorbitol which can then be converted to fructose
What are the essential amino acids?
Phenylalanine, Valine, Tryptophan, Threonine, Isoleucine, Methionine, Histidine, Leucine, Lysine
Hyperammonemia, increased ornithine
N-acetylglutamate deficiency (necessary cofactor of CMP-1 in urea cycle)
Increased orotic acid in blood and urine, low BUN and symptoms of hyperammonemia in the first few days of life
Ornithine transcarbamylase deficiency (Urea cycle, most common)
How is ornithine transcarbamylase deficiency inherited?
XLR
MR, growth retardation, seizures, fair skin, eczema, musty body oder
Phenylketonuria
What enzyme is deficient in PKU?
Phenylalanine hydroxylase
How is PKU transmitted, how is it detected and how is it treated?
- AR
- Screening 2-3 days after birth
- Decrease phenylalanine, increased tyrosine and avoid artificial sweetner
Dark connective tissue, dark brown sclerae, urine turns black on prolonged exposure to air
Alkaptonuria, cannot degrade tyrosine
What enzyme is deficient in alkaptonuria?
Homogentisate oxidase
High levels of homocystine in the urine, MR, osteoporosis, tall stature, kyphosis, lens subluxation
Homocystinuria
What enzyme is deficient in homocystinuria?
- Cystathionine synthase, OR
- B6, OR
- Homocysteine methyltransferase
Renal stones at a young age
Cystinuria
What enzyme is deficient in cystinuria?
Renal PCT and intestinal amino acid transporter of Cystine, Ornithine, Lysine and Arginine
How do you treat cystinuria?
Alkalinize the urine
CNS defects, MR, urine that smells like burnt sugar, death
Maple Syrup Urine Disease
What enzyme is deficient in maple syrup urine disease?
Decreased amounts of alpha-ketoacid dehydrogenase (can’t break down branched amino acids, ILV)
