Note:
For paediatric samples a minimum of 0.5ml blood EDTA can be processed. (Microcollect)
Transport all bloods at room temperature within 24-48 hours. If necessary specimens can be refrigerated overnight for transport at room temperature the following day.
For testing of other sample types please contact the laboratory prior to sending.
Urgent TAT for prenatal analysis: 2 weeks
METHOD: The Asuragen AmplidexTM FMR1 PCR kit and fluorescence-based capillary electrophoresis are used to detect CGG repeat expansions within the FMR1 gene - NM_002024.6, NP_002015.1. Due to the nature of the assay, we estimate that the CGG repeat allele sizing is correct to +/-1 repeat for alleles within the normal to intermediate range, and +/-2 repeats for alleles within the premutation range.
LIMITATION: This test cannot exclude the possibility of mosaicism; it cannot exclude the possibility of a null allele due to the inability of the primers to bind (as a consequence of variant genomic sequences); it cannot detect a deletion or point mutation within the FMR1 gene.
More than 99% of individuals with fragile X syndrome have a full mutation in the FMR1 gene caused by an increased number of CGG trinucleotide repeats (>200 typically) accompanied by aberrant methylation of the FMR1 gene. All individuals with FXTAS and all females with FMR1-related POI (Primary Ovarian Insufficiency) have an FMR1 premutation (increased number of trinucleotide repeats ranging from 55 to ~200).
REFERRAL REQUIREMENTS:
Diagnostic referral <15yrs through a Specialist Service.
Diagnostic referral >15yrs requires referral through Neurology, Psychiatry or Genetic Services.
All predictive/carrier only through Genetic Services.
Premature ovarian failure referrals can be accepted through Obstetrics.
LabPlus does NOT perform Fragile X analysis for preconception carrier testing unless there is a proven family history or the patient has clinical features consistent with a diagnosis of Fragile X syndrome.
IMPORTANT NOTES: Clinical details must be provided. Failure to provide the relevant details may delay testing.
CONTACT:
Genetic Health Service NZ can be contacted on 0800 476 123.
Neurology can be contacted on (09) 307 4949 ext. 25662.
To contact the Molecular Genetics team:
Auckland City Hospital
(09) 307 4949
Lablink
ext 22000
Molecular Genetics Office
ext 22014
Transport all bloods between >8 degrees C to < 25 degrees C within 24-48 hours. If necessary specimens can be refrigerated overnight (4 degrees C) for transport at the temperatures stated above the following day.
For testing of other sample types please contact the laboratory prior to sending.