Carrier screening or diagnostic testing for glycogen storage disease type 1A for individuals of Ashkenazi Jewish descent.
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Plasma or serum. Specimens collected in sodium heparin or lithium heparin tubes.
- Ambient: 72 hours; Refrigerated: 2 weeks; Frozen: 1 month
Characteristics: Infants typically present at 3 to 4 months of age with hepatomegaly, lactic acidosis, hyperuricemia, hyperlipidemia, hypertriglyceridemia and/or hypoglycemic seizures. Other characteristics include growth delay leading to short stature, osteoporosis, delayed puberty, renal disease, and hepatic adenomas with potential for malignancy. With treatment, affected individuals often live into adulthood.
Incidence: 1 in 20,000 in Ashkenazi Jewish individuals.
Inheritance: Autosomal recessive.
Cause: G6PC pathogenic variants.
Variants Tested: p.Q27Rfs (c.79delC), Y128Tfs (c.379_380dupTA), p.R83H (c.248G>A), p.R83C (c.247C>T), p.G188R (c.562G>C), p.Q242X (c.724C>T), p.Q347X (c.1039C>T), p.G270V (c.809G>T), p.F327del (c.979_981delTTC).
Clinical Sensitivity: 99 percent in Ashkenazi Jewish individuals; varies by ethnicity in non-Ashkenazi Jewish individuals.
Methodology: Polymerase chain reaction (PCR) and fluorescence monitoring.
Analytical Sensitivity and Specificity: Greater than 99 percent.
Limitations: Variants other than those tested will not be detected. Diagnostic errors can occur due to rare sequence variations.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|2013741||Glycogen Storage Disease, Specimen|
|2013742||Glycogen Storage Disease, Allele 1|
|2013743||Glycogen Storage Disease, Allele 2|
|2013744||Glycogen Storage Disease, Interp|
- Gierke disease