PATH - Glycogen storage diseases

Question 1

Von Gierke disease (type I)

Answer 1

Deficient:
*Glucose-6-phosphatase

Severe fasting hypoglycemia,
INC INC Glycogen in liver, INC blood lactate, INC triglycerides, INC uric acid (Gout), and hepatomegaly.

Impaired gluconeogenesis and
glycogenolysis

all resulting in abnormal glycogen metabolism and an accumulation of *glycogen
within cells.

Periodic acid–Schiff stain
identifies glycogen and is useful in identifying these diseases.

TX: frequent oral
glucose/cornstarch; avoidance
of fructose and galactose

Question 2

Pompe disease (type II)

Answer 2

Deficient:
Lysosomal α-1,4-glucosidase
with α-1,6-glucosidase activity
(acid maltase)

Cardiomegaly, hypertrophic
cardiomyopathy, exercise
intolerance, and systemic
finds leading to early death

all resulting in abnormal glycogen metabolism and an accumulation of *glycogen
within cells.

Periodic acid–Schiff stain
identifies glycogen and is useful in identifying these diseases.

Pompe trashes the Pump
(heart, liver, and muscle)

Question 3

Cori disease (type III)

Answer 3

Deficient:
Debranching enzyme
(α-1,6-glucosidase)

Milder form of von Gierke
(type I) with normal blood
lactate levels. Accumulation
of limit dextrin–like
structures in cytosol.

Gluconeogenesis is intact

all resulting in abnormal glycogen metabolism and an accumulation of *glycogen
within cells.

Periodic acid–Schiff stain
identifies glycogen and is useful in identifying these diseases.

Question 4

McArdle disease (type V)

Answer 4

Deficient:
Skeletal muscle glycogen
phosphorylase
(Myophosphorylase)

INC glycogen in muscle, but
muscle cannot break it down-->painful Muscle cramps,
Myoglobinuria (red urine)
with strenuous exercise, and
arrhythmia from electrolyte
abnormalities. 
-Second-wind phenomenon noted during
exercise due to  muscular
blood flow.

McArdle = Muscle

all resulting in abnormal glycogen metabolism and an accumulation of *glycogen
within cells.

Periodic acid–Schiff stain
identifies glycogen and is useful in identifying these diseases.