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ID:253 Glutamic acid Decarboxylase (GAD) antibodies
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DescriptionThere are two forms of Glutamic acid decarboxylase (GAD): GAD65 and GAD67. This ELISA assay detectes autoantibodies to GAD65. Anti-GAD Ab are specific for Type 1 insulin dependent diabetes mellitus (IDDM) and Stiff Persons Syndrome (SPS). GAD protein is most highly expressed in the brain and in the islets of Langerhans.
IndicationAutoantibodies to GAD are associated with IDDM and Stiff-person syndrome.
Additional InfoGAD converts glutamic acid to gamma-aminobutyric acid that is involved in the control of release of insulin from secretory granules. It is not specific for pancreatic beta cells as it is also found in the cerebellum, sympathetic ganglia and testis.
Concurrent TestsPancreatc Islet Cell Ab
Dietary Requirementsna
Interpretation70-80% of newly diagnosed IDDM are positive for anti-GAD antibodies as are 50% of relatives. These antibodies disappear with progression of disease (1-2 yrs). The presence of anti-GAD Ab can confirm the clinical diagnosis of SPS. 60-70% of patients with Stiff-person syndrome have anti-GAD antibodies. Note, as SPS can co-exist with IDDM, false positive results may occur where IDDM is present and the diagnosis of SPS is not clear.

DepartmentClinical Immunology
TubeSerum Gel
Tube Picture
Collection ConditionsNo restrictions
Min. Vol5ml
Freq.Referred to Sheffield

Ref. Range (Male)
Ref. Range (Female)
Ref. Range (Paed)
Ref. Range NotesInterpretative - Pos/Neg
Units - Not Defined -
IP Acute TAT- Contact Laboratory
IP Routine TAT7 days
GP Acute TAT- Contact Laboratory
GP Routine TAT7 days
Turnround CommentNA

Originally edited by : T.Bradley. Review due on 14/09/2018 14:28:27. Published By AM on 14/09/2017 14:28:27.