Hereditary Hyperferritinaemia Cataract Syndrome: FTL Sequencing

Diagnostic Use

Hereditary hyperferritinaemia cataract syndrome is an autosomal dominant disorder caused by heterogeneous mutations on the iron-responsive element of ferritin L-chain subunit mRNA. The mutations abolish or reduce affinity with iron-regulatory-proteins and this determines a constitutive up-regulation of ferritin L-chain in serum and all tissues. The high accumulation of L-ferritin in serum and tissues has no effect on body iron but the aggregation of the protein in the lens is associated with early bilateral cataract onset. Sequencing the 5’ untranslated flanking region of ferritin L-chain DNA will be able to identify the mutation.

Department

Genetics - Molecular Pathology

Delphic Registration Code

MOLP

Constituent Tests

• Genomic DNA Extraction

Synonyms

L-ferritin

Turnaround Time

4 weeks

Test Code

7312

Specimen Type

• Whole Blood

Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

4.0

No of Samples Required

1

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

1.0

Minimum Sample Volume (ml)

0.5

Additional Specimen Information

This test requires nucleated cells. Please do not centrifuge or freeze blood samples
If storing blood tube prior to delivery please refrigerate at 4 degrees (transport still at ambient temperature).

Aliquot Instructions

Sample Type

• Whole Blood

Transport to Lab

Ambient (8 - 24 degrees Celsius)

Additional Referral/Aliquot Information

Please do not centrifuge or freeze blood samples
If storing blood tube prior to delivery please refrigerate at 4 degrees (transport still at ambient temperature).

Test Method

The 5’ untranslated flanking region and exon 1 of ferritin L-chain DNA is amplified by PCR and sequenced by bi-directional automated fluorescent DNA sequencing. The remaining 3 exons and flanking intronic sequences can also be analysed if clinically appropriate.

Contact Canterbury Health Laboratories on +64 3 364 0484 or email LabInfo@cdhb.health.nz

Uncertainty of Measurement:
Automated bidirectional DNA sequencing has an analytical sensitivity and specificity of >99%. Note that the lower limit of variant detection of sequencing analysis is ~10%, this is important to consider in the case of mosaicism, mitochondrial, and somatic variation that is not expected to be present at 50% or 100%. This analysis will not detect variants located within intronic regions, except at the intron-exon boundaries.

Genomic DNA must be extracted from the specimen prior to testing. This incurs an additional charge (see GDNA). Laboratories may prefer to submit DNA for testing. Please provide a minimum of 5 micrograms of DNA at 20 nanograms/microlitre.

Contact Information

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