a) Glycogen storage diseases are inherited metabolic disorders. Metabolism is a mechanism to supply energy to the body and various enzymes are associated with it. Types of GSD are classified based on the deficiency of any of the enzymes associated with it.

GSD type 0 also called glycogen synthetase deficiency attacks only liver and the major difference between this type and the rest is that it doesn’t store abnormal glycogen but only stores decreased glycogen in liver. This is due to mutation in gene at locus 12p12. Diagnostics include measuring serum glucose levels and serum lipids and imaging tests like skeletal radiography. (Lerardi-curto L, 2010)

GSD type 1a caused due to mutation at loci 17q21 leading to the deficiency of true enzyme glucose 6 phosphatase (G6Pase) and GSD type 1b caused due to mutation at loci 11q23 that leads to the deficiency of glucose 6-phosphate transporter (G6PT). Diagnosis is usually based on analysis of various genetic mutations and Initial test is to measure blood for glucose levels with electrolytes, CBC count, Ultrasonography of Liver and kidneys. (Roth K S, 2009)

Molecular Genetic Testing is usually done for the genes, G6PC and SLC37A4 that result in the disease. (Bali D S and Chen Y T, 2008).

GSD type II is due to the deficiency of activity of acid alpha-glucosidase that is caused by the mutation at 17q23. Muscle biopsy and activity of alpha-glucosidase is measured for diagnosis and imaging studies include echocardiography (Ibrahim J and McGovern M M, 2010).

Sequence analysis and deletion/duplication analysis are molecular testing methods that help in analysis of genetic mutations. (Tinkle B T and Leslie N, 2010).

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GSD type III is due to mutation at AGL gene (Amylo-1, 6-glucosidase) and this result in dysfunction of liver and muscle. Four forms of GSD III have been observed till date. Liver function is accessed for prothrombin and transaminases levels and DNA is isolated from blood and analysis of AGL gene is performed clinically. Various imaging methods include ultrasonography of abdomen and electromyography. (Tegay D H and Jose R, 2009).

GSD type IV or Andersen disease is due to mutation at 3p12 and activity of GBE1 (glycogen-branching enzyme) is reduced. This results in failure and cirrhosis of liver. ...

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