Glycogen storage diseases Flashcards
Enzyme affected: glucose-6-phosphatase
What is it called, how is glycogen levels, which tissues affected, symptom and treatment.
GSD Type 1: Von Gierke disease
Can’t produce glucose for export leading to hypoglycemia.
Glycogen levels are somewhat elevated, structure is normal
Affects the liver and kidneys
Will have
- hyperlipidemia (fatty acid oxidation)
- Hyperuricemia (free phosphate is sequestered to glucose-6-phosphate. ATP can’t be regenerated and instead ADP becomes AMP > uric acid generated and you are vulnerable to gout
- lactic acidosis > since uric acid and lactate trade off, increased lactate lowers uric acid excretion
Treatment: feed carbs
Enzyme affected: a-1,4 glucosidase
What is it called, how is glycogen, which tissues affected, symptom and treatment.
Pompe’s trashes the pump
Type II Pompe’s
Enzyme alpha 1,4 glucosidase is responsible for glycogen breakdown in LYSOSOMES.
Glycogen accumulates in lysosomes, structure is normal
The tissue affected is the heart
- leads to cardiomegaly and left ventricular hypertrophy
- usually fatal by age 2
Treatment: enzyme replacement therapy
Enzyme affected: alpha-1,6- glucosidase
What is it called, how is glycogen levels, which tissues affected, symptom and treatment.
Girl name Cori stuck in a tree, she can’t get DEBRANCHED
The glycogen has way more branches which or shorter in length of glycogenolysis is hindered in general. More glycogen too.
Hypoglycemic because glycogen can’t be broken down and hepatomegaly as glycogen is trapped in the liver.
Treatment: frequent feedings and high protein diet. Similar to Type 1.
Enzyme affected: alpha 4,6 glucosidase
What is it called, how is glycogen, which tissues affected, symptom and treatment.
Anderson’s Type 4
Bad 4 Mr Anderson, wants to branch out with his clones but can’t.
4,6 glucosidase is the BRANCHING enzyme,
The glycogen has no branches, there are long insoluble chains. Glycogen levels are NORMAL how?…
*its either abnormal structure or abnormal amount.
Insoluble chains build up in the liver causing cirrhosis or hepatomegaly. Patients will die.
Enzyme affected: Glycogen phosphorylase (muscle)
What is it called, how is glycogen, which tissues affected, symptom and treatment.
McArdles Type 5
McArdles = muscle phosphorylase
Glycogen: structure is normal but accumulates
Can’t break down glycogen in muscle so it accumulates, leading to cramps and weakness, can lead to myoglobinuria due to excessive muscle breakdown.
Treatment: Oral glucose as glycolysis still functions.
Enzyme affected: glycogen phosphorylase in liver
What is it called, how is glycogen, which tissues affected, symptom and treatment.
Hers = hepatocytes
Hers’ Type 6
Glycogen: structure is normal and accumulates, increased amount
Tissue affected is liver. Leads to hepatomegaly and fasting hypoglycemia.
Gluconeogenesis is still intact so it will be less hypoglycemic than von gierkes with the g6phophatase deficiency.
Enzyme deficiency: muscle phosphofructokinase
What is it called, how is glycogen, which tissues affected, symptom and treatment.
Tarui’s Type 7
Taro is sugary, start with glucose not glycogen.
PFK converts fructose 6 phosphate to fructose 1,6 bisphosphate so that G3P can be formed and glycolysis can proceed.
Without it, glycolysis is impeded in muscle.
Glycogen is normal structure, increased amount
Similar presentation to McArdles
- reduced exercise tolerance
- myoglobinuria
- hemolytic anemia
How to tell apart?
Tarui won’t respond to oral glucose and also will have hemolytic anemia.
