Lab Test

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Prenatal Fragile X Syndrome, Amniotic Fluid or CVS

Test Codes

EPIC: LAB7961, Beaker: XPFRGX, DMC: 332122 and 323022

Department

Send Outs

Instructions

Prior to specimen collection, contacting the Send Outs Laboratory at 248-551-9045 is required to arrange for analysis of the sample.

Specimen Collection Criteria

Collect: Amniotic fluid or T-25 Flasks, collected as follows:

  • Amniotic Fluid: Collect 20-30 mL amniotic fluid into sterile 15 mL centrifuge tubes.
  • T-25 Flasks: Amniotic fluid cells, chorionic villus cells, or products of conception cells in two sterile, confluent T-25 flasks containing tissue culture transport medium.

Additionally, collect 3-5 mL of maternal peripheral blood in one Lavender-top EDTA tube for maternal contamination studies.

Physician Office/Draw Specimen Preparation

Do not freeze specimen. Maintain specimens refrigerated (2-8°C or 36-46°F) prior to transport.

Preparation for Courier Transport

Transport: Amniotic fluid or T-25 Flasks, and whole blood, refrigerated (2-8°C or 36-46°F).

Rejection Criteria

  • Specimens received without prior Laboratory notification and review.
  • Frozen specimens.
  • Specimens not collected and processed as indicated. 

In-Lab Processing

Do not freeze specimen. Maintain specimens refrigerated (2-8°C or 36-46°F) prior to transport.

Transport: Amniotic fluid or T-25 Flasks, and whole blood, refrigerated (2-8°C or 36-46°F).

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 72 hours
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Detroit Medical Center (DMC) University Laboratories, Detroit, MI.

Performed

Once a week.
Results available in 14 days.

Reference Range

By report.

Test Methodology

Cell Culture, DNA Extraction from Cells and Analysis of the Fragile X Gene.

Interpretation

Limitations of the procedure include:

  • Failure of cells to grow in culture may preclude analysis.
  • Admixture of maternal cells is a rare source of error.
  • The limits of reliability for determination of FMR-1 status have not been established.
  • Data should be combined with phenotypic and pedigree data for accurate interpretation.

Clinical Utility

This assay aids in the evaluation of FMR-1 status in a fetus at-risk of inheriting a mutation in the FMR-1 gene. An at-risk fetus is one with a documented Fragile X syndrome family member.

CPT Codes

81243, 81265.

Contacts

Last Updated

9/18/2023

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