1. Deficiency of Glucose-6-phosphate dehydrogenase
G-6-PD catalyzes the first step of pentose phosphate pathway which produces NADPH. Due to the defect, all the functions performed by the NADPH are altered. Genetics defects of G-6-PD is common in people of Mediterranean and Afro-Caribbean origin. The gene is mainly on X-chromosome, so males are mostly affected by this disorder. The defect is manifested as hemolytic anemia.
Causes:- Infections, certain drugs like anti-malarial drugs, food items like feva beans, henna, high dose of intravenous Vitamin C
Treatment:- Aspirin (high doses), Nonsteroidal anti-inflammatory drugs (NSAIDs), Sulfa drugs., Antibiotics such as quinolones
2. Glycogen storage disease or Glycogenosis
This is a group of genetic disease that results from the defect in the in an enzyme which is essential for both glycogen synthesis as well as degradation; and characterized by deposition of normal or abnormal deposition of glycogen in specific tissues.
Causes:- Enzyme deficiency which stops both glycogen synthesis and degradation, hereditary, acquired
Treatment:- Surgical care, consultations to the doctor, diet, long term monitoring etc.
3. Diabetes Mellitus
It is a syndrome of disorder of carbohydrate, protein, and fat metabolism. It is caused either due to lack of insulin secretion, or decreased sensitivity of the tissues to the insulin. Diabetes mellitus is broadly divided in two groups:-
- Type-1 diabetes mellitus or insulin dependent diabetes mellitus(IDDM):- It is also known as juvenile onset diabetes. Its symptoms include frequent urination, excessive thirst, excessive hunger ketoacidosis etc.
Causes:- It is caused due to lack of insulin secretion because of destruction of pancreatic beta-cells they cause destruction of the beta cells due to: viral infection, autoimmune disorder or hereditary of beta-cell degeneration.
Treatment:- Carbohydrate, protein fat count, frequent blood sugar monitoring, taking insulin.
- Type-2 diabetes mellitus or non-insulin dependent diabetes mellitus(NIDDM). Its symptoms include obesity, excessive hunger, excessive thirst but not ketoacidosis.
Causes:- Caused by decreased sensitivity of target tissues to insulin. This happens due to inadequate insulin receptors on the cell surface of the target tissues.
Treatment:- It can be treated
- At early stage by diet control, exercise, weight reduction and no exogenous insulin administration is required.
- Drugs that increases insulin sensitivity or drugs that causes more release of insulin by pancreas.
- In last stages, insulin administration is required.
4. Pompe’s Disease
It is a kind of glycogen storage diseases. In this disease, glycogen accumulates on the lysosomes in almost all the tissues especially heart, enlarged liver. The defective enzyme in this disease is lysosomal alpha-1, 4 glucosidase (acid maltase). This disease can also cause death at an early age due to heart failure.
Causes:- This is a genetic disorder. The defective gene is located on an autosome. It is caused due to deficiency of alpha glucosidase which breaks the complex sugars.
Treatment:- These are treated according to their symptoms. Physical and occupational therapy is helpful. It can be diagnosed by chest X ray, electrocardiogram and echocardiography.
5. Wernicke-Korsakoff syndrome
It is a HMP-shunt disorder. It is a genetic disorder in which alteration in the activity of transketolase enzyme occurs. This alteration reduces its affinity with thiamine pyro-phosphate. The symptoms include:
- Mental disorder
- Memory loss
- Partial paralysis
Causes:- Caused due to thiamine (Vitamin B1 deficiency), chronic alcoholics, liver and stomach damage etc.
Treatment:- Immediate administration of thiamine. Dose 500mg of thiamine is prescribed to the patients. Other than this, banana bag, a bag of intravenous fluids containing vitamins is also helpful.
6. Cancer and Glycolysis
The cancer cells shows increased uptake of glucose. As the tumors grow, the blood vessels are unable to supply adequate oxygen and thus causes hypoxia. Due to this anerobic glycolysis occurs mostly and supply oxygen. Hypoxia-inducible transcription factor (HIF) increases the synthesis of glycolytic enzymes and glycolytic transporters.
Causes:- It is caused due to acid- producing breakdown of glucose during glycolysis.
Treatment:- Since cancer cells cannot survive and grow without vascularization. So for the treatment drugs that inhibit the vascularization will be helpful.
Multiple choice questions (MCQs)
1. Deficiency of glucose-6-phosphate dehydrogenase is the disorder of which pathway?
A. HMP shunt
D. Glycogen metabolism
2. What is the product of glucose-6-phosphate dehydrogenase?
3. glycogenosis is the disorder of which pathway?
B. Glycogen metabolism
4. What type disease is glycogenosis?
B. Physically acquired
C. Chemically acquired
D. All of the above
5. Match the following treatment and its disorder-
A. Deficiency of G-6-PD 1. Nonsteroidal anti-inflammatory drugs
b. Glycogenosis 2. Long term monitoring
c. Diabetes mellitus 3. Insulin injection
6. What causes deficiency of G-6-PD?
A. Anti-malarial drugs
B. Feva beans
C. Glucagon deficiency
D. Both A and B
7. What are the causes of diabetes mellitus?
A. Lack of insulin receptor in tissue cells
B. Lack of glucagon receptor in tissue cells
8. Diabetes is the disorder of which metabolism?
A. Carbohydrate metabolism
B. Phospholipid metabolism
C. Fructose metabolism
D. Cholesterol metabolism
9. Diabetes mellitus is caused due to the deficiency of which hormone?
D. None of the above
10. How many types of diabetes mellitus?
11. Which of the following statement is NOT true?
A. Deficiency of G-6-PD mainly occur in afro-caribbean people
B. Deficiency of G-6-PD can cause hemolytic anemia
C. Deficiency of G-6-PD is common in females
D. Deficiency of G-6-PD is caused due to high IV of vitamin C
12. What is the cause of glycogenosis?
A. Enzyme deficiency which stop the processes
B. Due to lack of co-enzymes
13. What is the treatment of diabetes mellitus?
B. Long term monitoring
C. Insulin injection
D. All of the above
14. Type 2 diabetes mellitus is also known as?
15. Type 1 diabetes mellitus is also known as?
3. Glycogen metabolism
5. a – 1 b – 2 c – 3
6. Both A and B
7. Lack of insulin receptor in tissue cells
8. Carbohydrate metabolism
9. None of the above
11. Deficiency of G-6-PD is common in females
12. Enzyme deficiency which stop the processes
13. All of the above
REFERENCE:- 1. Pankaja Naik- Biochemistry; 4th edition; page no:- 187, 190, 197 and 198
2. U Satyanarayana, U Chakrapani- Biochemistry; 4th edition; page no- 249, 250, 269, 275.