GLYCOGEN STORAGE

DISEASE TYPE 1A

HERMAN NDJAMENGROUP 205

OBJECTIVES• GENERAL INTRODUCTION• HISTORY• CAUSES OF DISEASE• SIGNS AND SYMPTOMS• LABORATORY DIAGNOSIS• TREATMENT• END.

Glycogen Storage Disorders

Glycogen storage disorders are classified according to which enzyme is lacking or not working normally and also which part of the body is affected by the disease.

Glycogen storage disorders mostly tend to affect liver and muscles. However, some glycogen storage disorders can affect other parts of the body such as the kidney, heart, blood vessels, nervous system and bowel .The different types of glycogen storage disorder include:

Glycogen Storage Disorders Type Ia (von Gierke's disease), type Ib, type Ic, type Id. Type II (Pompe's disease). Type III (Forbes-Cori disease). Type IV (Andersen's disease). Type V (McArdle's disease). Type VI (Hers' disease). Type VII (Tarui's disease). Type IX (liver phosphorylase kinase deficiency). Type XI (Fanconi-Bickel syndrome). Type 0 (Lewis' disease). Type I glycogen storage disorder is the most

common. About one quarter of people who have glycogen storage disorder have type I. Type VIII and type X are now classified with type VI.

Glycogen-storage disease type I

Background In 1929, von Gierke provided the initial

description of glycogen-storage disease type I (GSD I) from autopsy reports of 2 children whose large livers contained excessive glycogen. He also reported similar findings in the kidneys.

Both children had frequent nosebleeds before their deaths, consistent with histories documented in current patients.

Glycogen-storage disease type I

In 1952, Cori and Cori reported 6 similar patients. Two of the patients had almost total deficiency of hepatic glucose-6-phosphatase, whereas the remaining 4 had normal enzyme activity.

These authors recognized that defects in the enzymology of hepatic glycogen-storage disease may cause a heterogeneous group of disorders.

Glycogen-storage disease type I

However, the mystery of patients with these clinical symptoms (despite normal phosphatase activity) remained unsolved until 1978, when Narisawa et al identified a defect in intracellular transport of the enzyme substrate.

Causes Glycogen-storage disease Ia is caused by deficient activity of the enzyme glucose-6-phosphatase, representing at least 14 distinct allelic variants.

ROLE OF GLUCOSE-6-PHOSPHATASE IN METABOLISM

•

• Glucose-6-phosphatase in the liver and kidney catalyzes the hydrolysis of glucose6phosphate to glucose during glycogenolysis.

SIGNS AND SYMPTOMS• Glycogen accumulation in liver and renal tubule

cells(hepatomegaly & renomegaly)• hypoglycemia; • lactic acidemia; • ketosis; • hyperlipemia

LABORATORY DIAGNOSIS• Some of the tests include: Blood glucose, blood

pH (to measure acidity), kidney function tests, complete blood count (to find anaemia, low neutrophil counts etc.), serum electrolytes, urine albumin, liver function tests (liver enzymes are usually normal), blood coagulation profile, cholesterol levels, and bone density measurement.

IMAGING• Ultrasound imaging of the abdomen to investigate

the enlarged liver (hepatomegaly), and assess the kidney for complications. In females, ultrasound may reveal polycystic ovaries

• Definitive diagnosis of Von Gierke Disease is by liver biopsy (examination of liver tissue), and assay of enzyme (glucose-6-phosphatase) activity.

TREATMENT• Patient’s diet should be followed-up by a

nutritionist to provide adequate calories, carbohydrate and proteins for growth. This is because the main aim is to avoid low blood glucose level.

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