Glycogen storage disease type 2 (GSD2)


Description

Glycogen storage disease type 2 (GSD2, MIM #232300) is an autosomal recessive inborn error of glycogen metabolism caused by deficiency of acid alpha-glucosidase (GAA), which is required for the degradation of lysosomal glycogen. GSD2 is characterised by lysosomal accumulation of glycogen in many body tissues as opposed to the exclusive cytoplasmic accumulation of glycogen that occurs in most other glycogen storage disorders. Clinical presentation varies from a rapidly fatal infantile disease to a slowly progressive late-onset myopathy frequently associated with respiratory insufficiency. Generally there is a correlation between the severity of the disorder and the amount of residual GAA activity. Incidence varies by ethnicity; in the Caucasian population the frequency of infantile disease is between 1:100,000 and 1:200,000 and late-onset disease possibly as high as 1:60,000. The GAA gene consists of 20 exons (exon 1 non-coding) and family specific mutations are found throughout the gene. Ethnic specific mutations are recognised and information regarding ethnic origin is a useful indicator. A mild splicing mutation in intron 1 (c.-32-13T>G) in combination with a more severe mutation is commonly associated with the late-onset phenotype in Caucasians.

Also known as

Pompe disease, acid maltase deficiency, GAA deficiency, acid alpha-glucosidase deficiency


Request a test

When requesting this test please use the referral form provided. Please also refer to any additional information provided for this test.


Additional information

Clinically affected patients should have their diagnosis confirmed by enzyme analysis; this should be arranged either locally or with the Enzyme Unit, Chemical Pathology, Great Ormond Street Hospital. Biochemically confirmed patients can be referred for mutation analysis. If the necessary patient samples are unavailable genetic testing can be undertaken in the parents of the affected child. Information regarding ethnic origin is useful.


Sending address

Great Ormond Street Hospital NE Thames Regional Genetics Service Laboratories
Great Ormond Street Hospital for Children
Barclay House
37 Queen Square
London
WC1N 3BH

Laboratory service

Genetics


Sample requirements

1ml EDTA neonates, 5ml EDTA adults


Reference range

Not applicable


Turnaround time

40 days


Disease / group

GAA


Cost

Upon request


Call in advance?

Prenatals must be arranged in advance, through a Clinical Genetics department if possible.


Genetics

The Genetics Laboratories provide an extensive range of Cytogenetics and Molecular Genetics diagnostic testing services.

© 2011 Great Ormond Street Hospital for Children NHS Trust