• Test Code:
    1550
  • Department:
  • Test Synonyms:
    Neurodegeneration with Brain Iron Accumulation NBIAFerritinopathyFerritin Light ChainFTL1
  • CPT Code(s):
    81479
Background:

NBIA is a group of neurodegenerative diseases caused by iron accumulation in the basal ganglia leading to dystonia, parkinsonism, neurocognitive anomalies, and ophthalmologic disorders.  Neuroferritinopathy is caused by mutations in the FTL gene (Ferritin Light chain), and is inherited in an autosomal dominant manner.  This disease is characterized by progressive adult-onset chorea or dystonia and cognitive deficits, and shows the presence of focal spherical inclusions in the brain and other organs, including liver and muscle.  In addition, mutations in the iron response element (IRE) of the FTL gene cause hereditary hyperferritinemia cataract syndrome (HHCS), a syndrome of early-onset cataract and hyperferritinemia.  The IRE is located in the 5’ untranslated region of the FTL mRNA.

Reasons for Referral:

  • Confirmation of a suspected clinical diagnosis in patients with the hallmark findings of neuroferritinopathy.
  • Further assessment of patients with clinical diagnosis of idiopathic Neurodegeneration with Brain Iron Accumulation (NBIA) who have had mutations ruled out in other NBIA genes.
  • Carrier testing of family members of FTL patients with known mutations.

Methodology:

Sequencing can be performed by either Sanger Sequencing or Next-Generation Sequencing.

Sanger Sequencing: Sequencing of FTL is carried out by amplification of all exons and intron/exon boundaries followed by bi-directional Sanger sequencing. The sensitivity of full gene sequencing is estimated to be approximately 99% for single nucleotide substitutions and small insertions/deletions. All nucleotide changes are analyzed within the context of current databases and literature to predict pathogenicity.

NGS: Next generation sequencing will analyze the exons or coding regions of FTL using Illumina NextSeq 500 technology. Samples are prepared using hybridization probes to enrich exonic regions. Promoter, intronic, etc. regions are not assessed on our assay, but may contain variants that impact gene function.Test reporting follows the ACMG Standards & Guidelines for Clinical Genetics Laboratories.

Specimen Requirements:

Blood: EDTA (purple top) or ACD (yellow top) (Solutions A or B):

  • Adult: 5 mL
  • Child: 5 mL
  • Infant: 2-3 mL

Prenatal:

  • Direct Amniotic Fluid (10-20mL)
  • Direct CVS
  • Cultured Amnio or CVS (2-T25 flasks)

DNA: 10µg at a minimum of 100ng/µL

Notice Regarding Molecular Genetic Testing on CVS or Amniotic Fluid Specimens:

  • Maternal cell rule-out testing will be performed on all prenatal specimens received. Please provide maternal blood in addition to the fetal specimen. Additional charges apply for the maternal cell rule-out test.
  • All genetic testing performed on Direct CVS or Amniotic Fluid specimens will be confirmed on cell cultures prepared by Knight Diagnostic Laboratories. Cell cultures will be prepared from the specimen received. Additional charges apply for confirmatory testing.

Test Performed (Days):

Weekly

Turn Around Time:

14-21 days

Shipment Sensitivity Requirements:

  • Package and ship specimen to remain cold, but not frozen. 
  • Ship via overnight express, using the FedEx priority overnight label provided. 
  • Contact Client Services for shipping kits and instructions at (855) 535-1522.

References:

  1. Curtis AR et al., (2001) Nat Genet. 28:350-354.
  2. Vidal R et al., (2004) J Neuropathol Exp Neurol. 63:363-380.
  3. Chinnery PF et al., (2006) Brain 130:110-119.
  4. Maciel P et al., (2005) Neurology 65:603-605.
  5. Mancuso M et al., (2005) J Neuropathol Exp Neurol. 64:280-294.

Additional Info:

Prior to any genetic testing we recommend genetic counseling.

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