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Paediatric Laboratory Medicine

Fragile X E Syndrome: FMR2 Trinucleotide Repeat Analysis

Clinical Significance

FRAXE is a form of non-syndromic X-linked intellectual disability characterized by mild intellectual disability. The FRAXE phenotype is quite variable, and tends to include slow learning, hyperactivity, attention problems and language delay. The gene associated with FRAXE is called FMR2. The normal gene contains a three base pair sequence, which is repeated on each X chromosome (called a CCG repeat). The principal mutation causing FRAXE is an expansion of the CCG repeat sequence within the FMR-2 gene.

Test Name

Fragile X E Syndrome: FMR2 Trinucleotide Repeat Analysis

Alternate Name/ Synonym

FRAXE syndrome

Gene Name

  • FMR2

Alternate Gene Name

FRAXE, AFF2

Test Code

FRAXE

Division

Molecular Genetics

Method

FMR2 5'UTR trinucleotide (CCG) repeat analysis via PCR

External Proficiency Testing

CAP

Turn Around Time

2 weeks (Prenatal samples), 2-3 weeks (Pregnancy/Urgent samples), 4-6 weeks (Routine)

Protein

AF4/FMR2 family, member 2

Disease/Condition

Fragile X E Syndrome

Specimen Type

Blood; gDNA.

For details about specimen requirements, please refer to: Specimen Type & Requirements (PDF).

Minimum Specimen Requirements

5-10 mL EDTA or ACD 0.5 mL EDTA (neonate); minimum 10 ug in 100 uL low TE (pH8.0)

Storage/Transportation

Room Temperature

Special Requirements

Special Instructions for Genome Diagnostics Samples

If sample shipment >48 hours, ship on ice.

The eligibility for this test is determined by the presence of a family history suggestive of X-linked intellectual disability; a pedigree must be provided for Fragile X E testing.

Approval is required

CPT Codes

81244

Shipping and Contact Information

The Hospital for Sick Children
Rapid Response Laboratory
170 Elizabeth Street, Room 3642
Toronto, ON
M5G 2G3
Canada
Phone: 416-813-7200
Phone: 1-855-381-3212

Interpretation

Interpretation is provided in report

Information Sheet: Fragile X E Syndrome