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Test Code MISCLM Fragile X Syndrome, Molecular Analysis

Additional Codes



Useful For

Determination of carrier status for individuals with a family history of fragile X syndrome or X-linked mental retardation


Confirmation of a diagnosis of fragile X syndrome, fragile X tremor/ataxia syndrome, or premature ovarian failure caused by expansions in the FMR1 gene


Prenatal diagnosis of fragile X syndrome when there is a documented FMR1 expansion in the family

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
CULFB Fibroblast Culture for Genetic Test Yes No
CULAF Amniotic Fluid Culture/Genetic Test Yes No
MATCC Maternal Cell Contamination, B Yes No
FUFXS Fragile X, Follow up Analysis No No

Testing Algorithm

When this test is ordered, fragile X follow-up analysis testing will be performed and charged dependent upon on the size of the CGG repeat found by PCR analysis.


For prenatal specimens only: If amniotic fluid (nonconfluent cultured cells) is received, amniotic fluid culture/genetic test will be added and charged separately. If chorionic villus specimen (nonconfluent cultured cells) is received, fibroblast culture for genetic test will be added and charged separately. For any prenatal specimen that is received, maternal cell contamination studies will be added.

Method Name

Polymerase Chain Reaction (PCR)-Based Assays

Reporting Name

Fragile X Syndrome, Mol. Analysis

Specimen Type


Advisory Information

Due to the complexity of prenatal testing, consultation with the laboratory is required for all prenatal testing.


FMR1-methylation status cannot be assessed on chorionic villus specimens. Contact a molecular genetic counselor/consultant at Mayo Medical Laboratories at 800-533-1710 to discuss the limitations of testing prior to sending a chorionic villus specimen for fragile X analysis.

Additional Testing Requirements

All prenatal specimens must be accompanied by a maternal blood specimen. Order MATCC / Maternal Cell Contamination, Molecular Analysis on the maternal specimen.

Shipping Instructions

Specimen preferred to arrive within 96 hours of collection.


Prenatal specimens can be sent Monday through Thursday and must be received by 5 p.m. CST on Friday in order to be processed appropriately.

Specimen Required

Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call Mayo Medical Laboratories for instructions for testing patients who have received a bone marrow transplant.


Submit only 1 of the following specimens:


Specimen Type: Whole blood


Preferred: Lavender top (EDTA) or yellow top (ACD)

Acceptable: Any anticoagulant

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.

Specimen Stability Information: Ambient (preferred)/Refrigerated


Prenatal Specimens


Specimen Type: Amniotic fluid

Container/Tube: Amniotic fluid container

Specimen Volume: 20 mL

Specimen Stability Information: Refrigerated (preferred)/Ambient


Specimen Type: Chorionic villi

Container/Tube: 15-mL tube containing 15 mL of transport media

Specimen Volume: 20 mg

Specimen Stability Information: Refrigerated



Specimen Type: Confluent cultured cells

Container/Tube: T-25 flask

Specimen Volume: 2 flasks

Collection Instructions: Submit confluent cultured cells from another laboratory.

Specimen Stability Information: Ambient (preferred)/Refrigerated

Specimen Minimum Volume

Blood: 0.5 mL
Amniotic Fluid: 10 mL
Chorionic Villi: 5 mg

Specimen Stability Information

Specimen Type Temperature Time
Varies Varies

Reject Due To

No specimen should be rejected.

Reference Values

Normal alleles: 5-44 CGG repeats

Intermediate (grey zone) alleles: 45-54 CGG repeats

Premutation alleles: 55-200 CGG repeats

Full mutation alleles: >200 CGG repeats

An interpretive report will be provided.

Day(s) and Time(s) Performed

Monday, Wednesday; 10 a.m.

Analytic Time

4 days

Performing Laboratory

Mayo Medical Laboratories in Rochester

CPT Code Information

81243-FMR1 (fragile 1 mental retardation 1) (eg, fragile X mental retardation) gene analysis; evaluation to detect abnormal (eg, expanded) alleles

Fibroblast Culture for Genetic Test

88233-Tissue culture, skin or solid tissue biopsy (if appropriate)

88240-Cryopreservation (if appropriate)


Amniotic Fluid Culture/Genetic Test

88235-Tissue culture for amniotic fluid (if appropriate)

88240-Cryopreservation (if appropriate)


Maternal Cell Contamination, B

81265-Comparative analysis using Short Tandem Repeat (STR) markers; patient and comparative specimen (eg, pre-transplant recipient and donor germline testing, post-transplant non-hematopoietic recipient germline [eg, buccal swab or other germline tissue sample] and donor testing, twin zygosity testing or maternal cell contamination of fetal cells (if appropriate)


81244-FMR1 (Fragile 1 mental retardation1) gene analysis, characterization of alleles (eg, expanded size and methylation status)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
FXS Fragile X Syndrome, Mol. Analysis In Process


Result ID Test Result Name Result LOINC Value
52870 Result Summary 50397-9
52871 Result 81856-7
52872 Interpretation 69047-9
52873 Reason for Referral 42349-1
52874 Specimen 31208-2
52875 Source 31208-2
52876 Method 49549-9
52877 Released By 18771-6

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.


1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.

2. Molecular Genetics: Congenital Inherited Diseases Patient Information (T521) in Special Instructions

3. If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen (