Glutaric Acidemia, Type I (GCDH) Sequencing
| Disorder | Glutaric Acidemia, Type I | |
| Gene Name | GCDH | |
| Clinical info | Glutaric acidemia, type 1 (GA1) is an autosomal recessive inborn error of lysine, hydroxylysine and tryptophan metabolism caused by the deficiency of glutaryl-CoA dehydrogenase (GCDH). Patients are often identified via newborn screening. However, some patients are “low excretors” and can exhibit normal or mildly elevated biochemical analytes making a definitive diagnosis of GA1 difficult without molecular analysis. GA1 is a neurodegenerative disorder with loss of neurons in the basal ganglia. Clinical features vary, but often include macrocephaly, gait abnormalities, hypotonia, spasms, rigidity and seizures. Retinal or subdural hemorrhages can also occur. Other than possible macrocephaly, patients appear normal at birth. Clinical features are typically preceded by an acute encephalopathic illness with fever before five years of age. | |
| Indications | Molecular testing is useful to confirm the diagnosis and to identify the disease causing mutations within a family to allow for carrier testing and prenatal diagnosis. | |
| Detection | Sequencing of the gene will detect mutations in 95% of individuals with glutaric acidemia type I. | |
| Associated Tests | C5-DC (glutarylcarnitine) | |
| Specimen Requirements | 5 to 10 ml of peripheral blood collected in an EDTA (lavender top) Vacutainer tube is preferred. The minimal blood needed for reliable DNA isolation is 3 ml | |
| Transport | The specimen should be kept at room temperature and delivered via overnight shipping. FedEx is preferred. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Samples collected on Friday can be safely designated for Monday delivery. | |
| Turnaround time | 2 weeks | |
| Prenatal testing | Prenatal diagnosis is available if the familial mutations are known. Additional fees for cell culture and maternal cell contamination may apply. Maternal cell contamination studies are required for all prenatal molecular tests Contact the laboratory prior to sending a prenatal specimen. | |
| CPT Codes | Unknown mutation 81406 Known mutation 81403 |
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| Cost | $1000 for sequencing $350 for known mutation |
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| Contact | For further information contact This email address is being protected from spambots. You need JavaScript enabled to view it. , MS, Lab Counselor at 1-800-473-9411. | |
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Kellie King, MS, CGC
Molecular Diagnostic Lab
The Molecular Diagnostic Lab offers DNA analysis for many genetic disorders via gene sequencing, targeted mutation analysis, MLPA deletion/duplication testing, trinucleotide repeat analysis and next generation sequencing panels.