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Ataxia/Episodic Ataxia Disorders (NGS Panel and Copy Number Analysis + mtDNA)

CPT: 81460, 81465, 81175, 81185, 81189, 81286, 81302, 81304, 81325, 81324, 81403, 81404 (x18), 81405 (x34), 81406 (x32), 81407 (x8), 81408 (x3), 81479 (x1)

Special Instructions

This assay is available for New York state.

Test orders should now be placed through Labcorp using test code 630930
 


Genes Assessed


      Specimen Requirements


      Specimen

      Room Temp whole blood, oral swab, extracted DNA (from blood, oral swab, or muscle only) OR frozen muscle tissue


      Volume

      Whole blood: 4 ml
      Oral swab: 3 swabs
      Muscle:  75 milligrams
      Extracted DNA: Contact MNG Genetic Services 844-664-8378 (844-MNGTEST)


      Minimum Volume

      Whole blood: 2 ml
      Oral swab: 1 swab
      Muscle:  50 milligrams
      Extracted DNA: Contact MNG Genetic Services 844-664-8378 (844-MNGTEST)


      Container

      Whole blood: Lavender-top (EDTA) 
      Oral swab: OCD-100 DNA Genotek
      Muscle:  Sterile screw capped vial
      Extracted DNA: Contact MNG Genetic Services 844-664-8378 (844-MNGTEST)


      Collection

      Whole blood: standard phlebotomy. 
      Oral swab: follow kit instructions
      Muscle: Snap freeze in liquid nitrogen and maintain at -80°C
      Extracted DNA: Contact MNG Genetic Services 844-664-8378 (844-MNGTEST)


      Storage Instructions

      Maintain whole blood and oral swab specimens at room temperature or refrigerate at 4°C. Do not freeze.  Muscle specimen: maintain frozen and ship on dry ice.


      Stability Requirements

      • Room temperature: Whole blood: 14 days; Swab: 60 days; Muscle:  0 days
      • Refrigerated: Whole blood: 30 days; Swab: 60 days; Muscle: 0 days
      • Frozen: Muscle: 15 years


      Causes for Rejection

      Hemolyzed, quantity not sufficient for analysis, improper container, improper storage temperature


      Test Details


      Use

      The hereditary ataxias are a group of genetic disorders characterized by slowly progressive incoordination of gait, and often associated with poor coordination of hands, speech, and eye movements. Frequently, atrophy of the cerebellum occurs. Inherited (genetic) forms of ataxia must be distinguished from the many acquired (non-genetic) causes of ataxia. The hereditary ataxias can be inherited in an autosomal dominant (AD), autosomal recessive (AR), X-linked, or mitochondrial manner, and multiple genes are involved. Early-onset ataxias, under 20 years of age, tend to be of autosomal recessive inheritance (e.g. Friedreich’s ataxia) whereas the spinocerebellar ataxias (SCAs) are autosomal dominant and tend to present mostly after 20 years of age; although both recessive and dominant can occur at any age. The prevalence of genetic childhood ataxia varies from 0.1 to 10 cases per 100,000 people. Ataxias due to mitochondrial disease may be an under-diagnosed cause of ‘inherited’ ataxia, but the pattern of inheritance may be complex, including maternal transmission, AD and AR inheritance. The diagnosis of hereditary ataxia is based upon detection and neurologic examination of typical clinical signs and symptoms, a positive family history, and molecular analysis. Hereditary ataxias can be subdivided first by mode of inheritance, and secondarily by the gene in which the pathogenic variants occur.


      Limitations

      This assay will not consistently detect mosaicism or rule out the presence of large chromosomal aberrations, including rearrangements and inversions that do not change copy number of genomic regions. This NGS assay does not detect repeat expansions. False positive or false negative results may occur for reasons that include insufficient information available about rare genetic variants, sex chromosome abnormalities, pseudogene interference, homologous regions, blood transfusions, bone marrow transplantation, somatic or tissue-specific mosaicism/heteroplasmy, mislabeled samples, or erroneous representation of family relationships. For panels with mitochondrial DNA assessment, low levels of heteroplasmy may not be reliably detected. Interpretation of the clinical significance of gene variations is limited by information about the variant that is available at the time of reporting, and by the quality and quantity of clinical information provided with the sample. The interpretation of the clinical significance of variants may change.

      This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.


      Methodology

      Next generation sequencing to identify single nucleotide variants (SNVs), insertions, deletions, and copy number variants (CNVs).  For the mitochondrial genome, next generation sequencing of long range PCR products. 


      Recommended MNG Kits

      SINGLE Blood Genetic Testing, Buccal Swab Genetic Testing