LAB738
FRAG X PCR
Collect
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
Internal: Deliver to lab immediatley at room temperature
Offsite: Deliver to lab at room temperature. Specimens may be accompanied by a completed DNA Analysis consent form (not required). Specimens from outside must be received within 48-72 hours of collection.
Stability (from collection to initiation)
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Remarks
Patient History Form is available on the ARUP website or by contacting ARUP Client Services.
Performed by
UCD DNA Diagnostics Laboratory
Notes
If a CGG repeat of 55 or greater is detected by PCR and Capillary Electrophoresis; methylation analysis will be added. Additional charges apply.
Laboratories.Performed
Sun-Sat
Methodology
Polymerase Chain Reaction/Capillary Electrophoresis
Reported
2 - 4 weeks
Synonyms
- LAB738
- FRAG X PCR
Additional Technical Information
Ordering Recommendations
Preferred test to diagnose fragile X syndrome and carrier screening in individuals with a positive family history.
Reference Interval
By report
Interpretive Data
Background Information for Fragile X (FMR1)
Characteristics: 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.
Incidence: 1 in 4,000 Caucasian males and 1 in 8,000 Caucasian females; unknown in other ethnicities.
Inheritance: X-linked dominant.
Penetrance: Reduced in females.
Cause: 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.
Methodology: 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.
Limitations: Diagnostic errors can occur due to rare sequence variations.
Characteristics: 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.
Incidence: 1 in 4,000 Caucasian males and 1 in 8,000 Caucasian females; unknown in other ethnicities.
Inheritance: X-linked dominant.
Penetrance: Reduced in females.
Cause: 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.
Methodology: 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.
Limitations: Diagnostic errors can occur due to rare sequence variations.
| Phenotype | Number of CGG Repeats |
|---|---|
| Unaffected | <45 |
| Intermediate | 45-54 |
| Premutation | 55-200 |
| Affected | >200 |
Performed by
UCD DNA Diagnostics Laboratory
CPT Codes
81243; if reflexed add 81244
| Collection |
LAB738
FRAG X PCR
Collect
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
Internal: Deliver to lab immediatley at room temperature
Offsite: Deliver to lab at room temperature. Specimens may be accompanied by a completed DNA Analysis consent form (not required). Specimens from outside must be received within 48-72 hours of collection.
Stability (from collection to initiation)
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Remarks
Patient History Form is available on the ARUP website or by contacting ARUP Client Services.
Performed by
UCD DNA Diagnostics Laboratory
Notes
If a CGG repeat of 55 or greater is detected by PCR and Capillary Electrophoresis; methylation analysis will be added. Additional charges apply.
| Ordering |
Performed
Sun-Sat
Methodology
Polymerase Chain Reaction/Capillary Electrophoresis
Reported
2 - 4 weeks
Synonyms
- LAB738
- FRAG X PCR
Additional Technical Information
Ordering Recommendations
Preferred test to diagnose fragile X syndrome and carrier screening in individuals with a positive family history.
| Result Interpretation |
Reference Interval
By report
Interpretive Data
Background Information for Fragile X (FMR1)
Characteristics: 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.
Incidence: 1 in 4,000 Caucasian males and 1 in 8,000 Caucasian females; unknown in other ethnicities.
Inheritance: X-linked dominant.
Penetrance: Reduced in females.
Cause: 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.
Methodology: 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.
Limitations: Diagnostic errors can occur due to rare sequence variations.
Characteristics: 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.
Incidence: 1 in 4,000 Caucasian males and 1 in 8,000 Caucasian females; unknown in other ethnicities.
Inheritance: X-linked dominant.
Penetrance: Reduced in females.
Cause: 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.
Methodology: 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.
Limitations: Diagnostic errors can occur due to rare sequence variations.
| Phenotype | Number of CGG Repeats |
|---|---|
| Unaffected | <45 |
| Intermediate | 45-54 |
| Premutation | 55-200 |
| Affected | >200 |
Performed by
UCD DNA Diagnostics Laboratory
| Administrative |
CPT Codes
81243; if reflexed add 81244