Metabolism Flashcards
What does galactokinase do and what results from a deficiency of it?
Converts glucose and galactose to galactose 1-phosphate + UDP glucose; deficiency is galactokinase deficiency where only symptom is cataracts
Galactosemia cause and symptoms
Deficiency of galactose-1-phosphate uridyl transferase (GALT)
Autosomal recessive
Poor feeding, vomiting, jaundice, helatomegaly, liver failure, lethargy, cataracts, E. coli sepsis
Cause of cataracts in galactosemia
Excess galactitol in lens, regress with good control of dietary lactose
Long term consequences of galactosemia
Older children with learning disabilities despite therapy; increased risk of premature ovarian failure even if treated appropriately
Laboratory findings in galactosemia
- Low glucose
- elevated liver function tests, elevated indirect bilirubin
- Decreased coagulation factors
- increased galactose in urine (represented by reducing substances, a positive urine Clinitest but negative clinistix urine test)
- Elevated galactose-1 phosphate
- Hyperchloremic metabolic acidosis due to rental tubular dysfunction
Enzyme in glycogen storage disease type I
Glucose-6-phosphatase (von Gierke’s disease)
Symptoms of glycogen storage disease type I
Lactic acidosis
Low glucose
Neutropenia (and increased risk of infection)
Hepatomegaly
FTT
Bleeding disorder (due to liver dysfunction)
Enzyme affected in type II glycogen storage disease
Lysosomal alpha-1,4-glucosidase (acid maltase)
Symptoms of Pompe’s disease
(Type II glycogen storage disease)
Symmetric severe muscle weakness
Cardiomegaly, CHF
Enzyme in type III glycogen storage disease
Debranching enzyme (alpha-1,6-glucosidase)
Cori disease vs Forbes disease
Symptoms of type III glycogen storage disease
Low glucose, ketonuria, hepatomegaly, muscle fatigue, normal lactate!
Enzyme in type IV glycogen storage disease
Branching enzyme
Symptoms of type IV glycogen storage disease
Cirrhosis beginning at several months of age, hypotonia, muscle weakness; no signs in neonatal period; very poor prognosis-death from liver failure <4 years of age unless liver transplant
Enzyme in type V glycogen storage disease
Muscle phosphorylase (McArdle)
Symptoms of type V glycogen storage disease
Muscle fatigue in adolescence, myoglobinuria with strenuous exercise, arrhythmia from electrolyte abnormalities, no increase in lactate after exercise
Enzyme in type VI glycogen storage disease, affected organ and symtpoms
Liver phosphorylase, liver affected
Mild hypoglycemia, ketonuria
Hepatomegaly
Enzyme in type VII glycogen storage disease, affected organ, and symptoms
Muscle phosphorfructokinase, muscle, muscle fatigue in adolescence
Enzyme in type VIII glycogen storage disease, affected organ, and symptoms
Phosphorylase kinase, liver
Similar to type III but no myopathy
Low glucose, ketonuria, hepatomegaly
What do you have to remove from diet in fructosemia?
Fructose, sucrose (fructose+glucose), and sorbitol (alcohol form of glucose but to use is converted to fructose)
Enzyme deficiency in fructosemia
Fructose 1-phosphate aldolase (aldolase B)
Expressed in liver, intestine, kidney
Symptoms of fructosemia
Vomiting, lethargy, seizures, failure to thrive, liver disease, proximal renal tubular dysfunction
Lab findings in fructosemia
Low glucose, abnormal LFTs, reducing substances in urine
Genetics and pathway affected in OTC deficiency
X-linked recessive
OTC converts carbamyl phosphate to citrulline in the mitochondria
Symptoms and labs in otc deficiency
Extremely elevated urine orotic acid, hyperammonemia, increased glutamine and alanine, decreased citrulline, decreased arginine