Fragile X (FMR1) with Reflex to Methylation Analysis
Ordering Recommendation
Preferred test to diagnose fragile X syndrome in individuals with characteristic clinical symptoms or screen healthy individuals for carrier status with or without a positive family history.
Polymerase Chain Reaction/Capillary Electrophoresis
4-14 days  
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).  
Specimen Preparation
Transport 5 mL whole blood. (Min: 1.5 mL)  
Storage/Transport Temperature
Room temperature. If transport time will exceed 48 hours: Refrigerated.  
Unacceptable Conditions
Patient History Form is available on the ARUP website or by contacting ARUP Client Services.  
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable  
Reference Interval
By report  
Interpretive Data
Background Information for Fragile X (FMR1)
Fragile X syndrome, the most common heritable form of mental retardation, is characterized by moderate mental retardation in males and mild mental retardation in females, hyperactivity, perseverative speech, social anxiety, poor eye contact, hand flapping or biting, autism spectrum disorders behavioral phenotype, and connective tissue anomalies. Adult males may have physical findings including: macroorchidism, a long narrow face, prominent ears and jaw, and a single palmar crease.
1 in 4,000 Caucasian males and 1 in 8,000 Caucasian females; unknown in other ethnicities.
X-linked dominant.
Reduced in females.
Expansion of the FMR1 gene CGG triplet repeat.
Full mutation:>200-230 CGG repeats (methylated)
Premutation: 55-200 CGG repeats (unmethylated)
Intermediate: 45-54 CGG repeats (unmethylated)
Normal: 5-44 CGG repeats (unmethylated)
Clinical Sensitivity:
99 percent.
Triplet repeat-primed polymerase chain reaction (PCR) followed by size analysis using capillary electrophoresis. Methylation-specific PCR analysis is performed for CGG repeat lengths of 55 or greater. Methylation analysis is used to distinguish between premutation and full mutation alleles.
Analytic Sensitivity and Specificity:
99 percent.
Diagnostic errors can occur due to rare sequence variations.

Compliance Statement C: The performance characteristics of this test were validated by ARUP Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test; however, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. ARUP is authorized under Clinical Laboratory Improvement Amendments (CLIA) and by all states to perform high-complexity testing.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
Phenotype Number of CGG Repeats
Unaffected <45
Intermediate 45-​54
Premutation 55-​200
Affected >200
If a CGG repeat of 55 or greater is detected by PCR and Capillary Electrophoresis; methylation analysis will be added. Additional charges apply.
CPT Code(s)
81243; if reflexed add 81244
Component Test Code*Component Chart NameLOINC
0050556Fragile X Allele 145321-7
0050558Fragile X Allele 245322-5
0050559Fragile X Methylation Pattern41107-4
0050579Fragile X Interpretation36913-2
2001310FRAG X Specimen66746-9
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • Inherited Mental Retardation (Fragile X (FMR1) Diagnostic)
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