Preferred molecular genetic test following biochemical testing suggestive of guanidinoacetate methyltransferase (GAMT) deficiency.
- 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
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: Intellectual disability and seizure disorder of variable severity. May also include speech / language delays, movement disorder, and behavioral disorders such as autism, hyperactivity, and self-injury.
Incidence: Unknown. More than 50 cases have been described.
Inheritance: Autosomal recessive.
Cause: Pathogenic GAMT gene mutations.
Clinical Sensitivity: Based on limited data, may be as high as 99 percent.
Methodology: Bidirectional sequencing of the entire coding region and intron/exon boundaries of the GAMT gene.
Analytical Sensitivity and Specificity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Regulatory region mutations, deep intronic mutations, and large deletions/duplications will not be detected. Mutations in genes other than GAMT are not evaluated.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.
|Component Test Code*||Component Chart Name||LOINC|
|2011141||GAMT Sequencing Specimen||31208-2|
|2011142||GAMT Sequencing Interpretation|
- GATM, Arginine:Glycine Amidinotransferase (AGAT) Deficiency, SLC6A8, creatine deficiency, creatine t