glycogen storage diseases

2. GLYCOGEN STORAGE
DISORDERS
These are a group of inherited disorders
associated with glycogen metabolism,
familial in incidence and characterized by
deposition of normal or abnormal type and
quantity of glycogen in the tissues

3. There are 6 classical types of glycogen
storage diseases
 Type1)Von gierke’s disease
Type2)Pompe’s disease
Type3)Limit dextrinosis(Forbe’s disease)
Type4)Amylopectinosis(anderson’s disease)
Type5)McArdle’s disease
Type6)Her’s disease

4. TYPE 1:Von gierke’s disease
ENZYME DEFICIENCY :glucose-6-
phosphatase
INHERITANCE : Autosomal recessive
Liver cells and intestinal mucosal cells
are fully loaded with glycogen and
metabolically unavailable

5. CLINICAL AND BIOCHEMICAL FEATURES OF VON
GIERKE’S DISEASE
 Only little amount of glucose is available is derived
from liver
 So the children with this disease may tend to develop
hypogycemia
 Fat is used as a energy source so it may lead to
LIPAEMIA,ACEDEMIA and KETOSIS
 Excess of Acetyl coA is diverted for chosterol synthesis
this may lead to elevated level of cholestrol and
results in XANTHOMAS

6. Cont….
 Increased fatty acid synthesis can produce fatty
infiltration of liver
 PERSISTENT HYPOGLYCAEMIA has 2 effects
Hypoglycemia inhibits insulin which in turn inhibits
protein synthesis which results in DWARFISM
Hypoglycemia stimulates the secretion of
CATECHOLAMINES which cause muscle glycogen to
break down producing lactic acid and LACTIC ACIDOSIS
 Increased blood lactic acid competes with urate
excretion by kidneys leading to increased blood uric acid
levels
 Children with increased uric acid synthesis may develop
the symptoms of GOUT

7. PROGNOSIS
Children with this disease
may die young and some
of them survive till
adolescence

8. TYPE 2: POMPE’S DISEASE
 ENZYME DEFICIENCY : ACID MALTASE enzyme
which is present in lysosome and catalyses the
breakdown of oligosaccharides
 INHERITANCE : AUTOSOMAL RECESSIVE
 Here the glycogen structure is normal and the
organs which are involved is
HEART,LIVER,SMOOTH MUSCLE,AND STRAITED
MUSCLE
 All the tissue contain excess of glycogen

9. CLINICAL FEATURES
 Enlargement of heart (cardiomegaly)
 Muscle weakness

10. PROGNOSIS
 Infants usually die due to cardiac failure and broncho
pnuemonia
 Death usually occurs before 9 months

11. TYPE 3 : LIMIT DEXTRINOSIS(FORBE’S
DISEASE)
 ENZYME DEFICIENCY : DEBRANCHING ENZYME
 INHERITANCE : AUTOSOMAL RECESSIVE
 GLYCOGEN STRUCTURE : LIMIT DEXTRIN TYPE
 Organs involved are heart liver and muscle

12. CLINICAL AND BIOCHEMICAL FEATURES
• HEPATOMEGALY
• MODERATE HYPOGLYCEMIA
• ACIDOSIS
• PROGRESSIVE MYOPATHY
• Enzyme deficiency can be
demonstrated in leucocytes

13. PROGNOSIS
 Survives well to adultlife

14. TYPE 4 : AMYLOPECTINOSIS(ANDERSON’S
DISEASE)
 ENZYME DEFICIENCY : BRANCHING ENZYME
 INHERITANCE : NOT DEFINETELY KNOWN
 Glycogen deposited is abnormal type, few
branch points and very long inner and outer
unbranched chains
 LIVER is the mainly affected organ and other
organs are HEART, KIDNEY, and MUSCLES
 Deposition is seen in RE SYSTEM

15. CLINICAL AND BIOCHEMICAL FEATURES
 HEPATOMEGALY
 SPLENOMEGALY
 MODERATE HYPOGLYCEMIA
 NODULAR CIRRHOSIS OF LIVER
 HEPATIC FAILURE
 Enzyme deficiency can be demonsrated in
leucocytes and liver

16. PROGNOSIS
 Usually fatal
 Longest survival is reported as 4 years

17. TYPE 5 : McArdle’s disease
 ENZYME DEFICIENCY : MUSCLE PHOSPHORYLASE
 INHERITANCE : AUTOSOMAL RECESSIVE
 Glycogen deposited in normalstructure and the organs
involved are skeletal muscles

18. CLINICAL FEATURES
Muscle cramps on exercise
Pain
Stiffness and weakness of muscles

19. EPINEPHRINE TEST
 After administration of epinephrine rise in
blood glucose occurs which shows that
hepatic phosphorylase activity is normal

20. TYPE 6 : Her’s disease
ENZYME DEFICIENCY : LIVER
PHOSPHORYLASE
Glycogen deposited is normal in
structure
Organs affected are mainly LIVER
and LEUCOCYTES

21. CLINICAL AND BIOCHEMICAL FEATURES
 HEPATOMEGALY
 MODERATE HYPOGLYCEMIA
 MILD ACIDOSIS