- OHSU Service Code:
- 102-8856
- Lab Section:
- Molecular Diagnostic Center
- Synonyms:
- Frax A Mental Retardation
- Test Schedule:
- Weekly. Result turnaround is 2 weeks.
- Specimen
Requirements:
- 6.0 mL whole blood in EDTA vacutainer tube. Prenatal testing is available; please consult with the lab at 503-494-5400 prior to obtaining or sending prenatal specimens. For requisition slips.
- Pediatric Specimen
Requirements:
- 3.0 mL blood, EDTA vacutainer tube.
- Reference Range:
- Measurement of CGG trinucleotide repeat number in exon 1 of the FMR-1 gene at Xq27.3.
Allele Types #CGG Repeats
Normal ~5 - ~44
Intermediate ~45 - ~54
Premutation ~55 - 200
Full mutation (i.e. disease-causing) >200
- Interpretation:
- 5 - 44 repeats: No clinical phenotype
45 -200 repeats: No clinical phenotype but genetic counseling
recommended.
>200 repeats: Clinically affected males; females at risk
for Fragile X syndrome.
- Comments:
- Testing is diagnostic for normal/carrier/disease states.
Fragile X Syndrome is the most common
hereditary cause of mental retardation.
Testing is indicated in mentally retarded
individuals and in individuals with a family
history of mental retardation or learning
disability of unknown etiology. Please call
the laboratory at 503-494-5400 for further
information and requisition forms.
