L.9 Pentose Phosphate/Sugar Metabolism Diseases

Question 1

Glucose-6-Phosphate Dehydrogenase Deficiency

Answer 1

• Acute Hemolytic Anemia
• RBCs exposed to more O2, Glutathione is main defense, only get NADPH from pentose phosphate pathway
• Low NADPH = Low active glutathione = Low ROS protection = cell damage by oxidation of membrane proteins and intracellular proteins = cell death
• Shorter RBC lifespan
• High bilirubin
• High reticulocyte
• Jaundice
• Fatigue, pallor, SOB

Question 2

Galactokinase Deficiency

Answer 2

• Galactose -> Galactose-1-P
• Galactosemia and galactosuria
• Galactictol accumulation = cataracts

Question 3

Classic Galactosemia

Answer 3

-Galactose- 1-P Uridyltransferase
-Galactose- 1-P -> UDP-glucose
-Galactose1P can’t leave cells
-Galactosemia, galactosuria, vomiting, diarrhea, jaundice
-Liver damage, MR, cataracts
Tx: remove dietary galactose

Question 4

Aldose Reductase

Answer 4

• Galactose + NADPH -> galactitol
• Enzyme is present in liver, kidney, retina, lens, nerve tissue, seminal vesicles, ovaries
• Unimportant enzyme except with high galactose levels
• Galactitol accumulation (can cause cataracts)

Question 5

Essential Fructosuria

Answer 5

-Fructokinase
-Fructose → Fructose 1P
-Fructose accumulation in urine
Benign condition

Question 6

Hereditary Fructose Intolerance (Fructose Poisoning)

Answer 6

-Aldolase B
-Fructose 1P –> glyceraldehyde/dihydroxyacetone-phosphate
-Fructose 1P is trapped in cells, also results in low ATP
-Severe hypoglycemia (no ATP for gluconeogenesis), vomiting, jaundice(bilirubin accumulation, from liver damage), hemorrhage (no clotting proteins from liver), hepatomegaly, lactic acidemia (no gluconeogenesis, so no lactic acid used from circulation) , hyperuricemia, hepatic failure, death
Tx: removal of fructose/sucrose from diet