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|Utilization Guidelines||Used in the assessment of patients with mental retardation, adult onset tremor/ataxia in men and/or premature ovarian failure in women.
Tests with long turn-around times (ie. Molecular based tests and Microarrays) should only be requested on an inpatient if the result is going to affect the inpatient management.
If the patient will likely be discharged before the result will be available, the test should be requested after discharge. (NOTE: UCSF Medical Center is not reimbursed for inpatient testing).
An exception to the above may be appropriate if there is a possibility the patient will not survive to be discharged and the information is important for diagnosis and/or family decisions/management (ie. recurrence risk).
|Performed by||Molecular Diagnostics|
|In House Availability||Run 2x per week, Wednesday & Friday, day shift only|
|Method||Southern blot for methylation analysis
PCR for number of CGG repeats
|Collection Instructions||If collecting in citrate, check the expiration date on the label of the blue top vacutainer before drawing the patient.
Do not collect sample in heparin. Keep sample refrigerated for overnight or longer storage.
For UCSF Samples (from remote sites) Click here for sample collection instructions
For NON-UCSF Samples Click here for Requisition form & Account set-up instructions. Note we only do institutional billing.
|Container type||Lavender top preferred, Blue (citrate) and Yellow (ACD) tops acceptable|
|Amount to Collect||3 mL blood|
|Sample type||EDTA whole blood, Amniocyte culture|
|Preferred volume||3 mL blood|
|Min. Volume||2 mL blood|
|UCSF Rejection Criteria||Samples collected in outdated blue top vacutainer.|
|Processing notes||Do not centrifuge the specimen. Store at room temperature. Refrigerated samples are acceptable.|
|Normal range|| Results are reported as "No Mutation Detected", "Pre-mutation Present" or "Full Mutation Present".
Number of CGG repeats is also reported.
|Synonyms||Mental retardation; ataxia; ovarian failure; FRAXA; FMR-1|
|Turn around times||10-14 days|
|Additional information|| An interpretation of this test by a laboratory physician will automatically be performed and billed for separately.
Presence of a full mutation with complete methylation is associated with mental retardation. Methylation mosaicism and/or premutation along with a full mutation has been shown to reduce the severity of mental retardation.
A premutation in a female is not associated with mental retardation. The presence of a full mutation in a female carries approximately 30% risk of mild mental retardation.
The chance that a premutation could expand to a full mutation when passed from a female carrier to her offspring is shown in the following table:
Adult onset disease:
Fragile X-associated tremor / ataxia syndrome (FXTAS). An FMR-1 premutation may confer an adult risk for tremor and ataxia. Not all men with an FMR-1 premutation will develop FXTAS. The risk of developing FXTAS is age dependent and ranges from 17% (age 50- 59), 38% (age 60-69), 45% (age 70- 79) and 75%(age ≥ 80). However, it is estimated that only 20-30% of men with an FMR-1 premutation will develop the syndrome.
FMR-1 related premature ovarian failure (POF): Women with an FMR-1 premutation have an approximately 21% risk of developing POF as opposed to 1% in the general population.
If a mutation is detected it is recommended that the patient seek genetic counseling.
This test was developed and its performance characteristics determined by the Clinical Laboratories at the Medical Center at UC San Francisco. It has not been cleared or approved by the U.S. Food and Drug Administration.
|CPT coding||81243, 81244|
|LDT or Mod FDA?||Yes|
|Last Updated||9/10/2013 8:45:29 AM|
If you have additional questions regarding this test, please call: 415-353-1667