Targeted Deletion/Duplication Testing

TEST NAME:   High Resolution Deletion/Duplication Testing
Also known as:   Del/Dup

INDICATIONS FOR TESTING:   High resolution deletion/duplication testing is recommended for any single gene condition for which another genetic etiology, such as a pathogenic sequencing mutation, is not identified. Additionally, this assay is useful for patients with a single suspicious or pathogenic mutation in a gene known to be associated with a recessive condition, as it has the potential to unveil a second aberration in the gene of concern. It is also helpful for patients who have findings suspicious of multiple potential genetic causes, generally as a result of either clinical ambiguity due to marked phenotypic overlap between various syndromes or numerous genetic causes for a single disorder, without an identified genetic etiology. Detailed information about the clinical indications for each of our gene panels can be found by accessing the indication-specific gene panel testing pages of our test menu.

TEST INFORMATION:   High resolution deletion/duplication testing interrogates the gene(s) of interest for intragenic or whole-gene dosage anomalies. This assay is able to analyze the target gene(s) at the exon level, allowing for enhanced detection and aberration mapping. While this testing is available for any single gene studied in our laboratory, this assay is most cost-effective when a panel of phenotypically-related genes is analyzed simultaneously. Please refer to our laboratory's Indication-Specific Gene Panel tests on the test menu.

ADVANTAGES:

  • High resolution deletion/duplication analysis allows for the detection of both whole-gene and intragenic dosage anomalies.
  • The design of this assay provides copy number information at the exon level, which is not consistently available with whole genome copy number assays.
  • For patients with an identified single mutation in a gene known to be associated with a recessive condition, this assay looks for small-scale genomic dosage anomalies that may be the second pathogenic aberration contributing to the phenotype.
  • High resolution deletion/duplication analysis is a cost-effective method of testing many potentially causative genes simultaneously rather than ordering separate deletion/duplication assays sequentially.
  • It allows for large scale testing on a small sample of blood.

LIMITATIONS:

  • This assay detects only genomic dosage anomalies (deletions and duplications) in the genes interrogated.
  • It does not provide whole-genome analysis or identify regions of homozygosity (ROH).
  • Unlike whole-genome copy number assays, this high resolution deletion/duplication test cannot be reliably used for breakpoint determination or refinement.
  • Despite dense probe coverage throughout the genes of interest, this assay is limited in its detection of genomic dosage anomalies by the probe density at a given locus.

RESULTS:

  • A normal result indicates that the high resolution deletion/duplication analysis of the target genes did not reveal any genomic dosage anomalies classified as pathogenic or as being of uncertain clinical significance.
  • An abnormal result indicates that a pathogenic genomic dosage anomaly was identified. Any available information regarding the phenotype (physical, developmental, and cognitive findings) associated with the deletion or duplication will accompany the technical details on the report.
  • In some cases, the clinical significance of an identified genomic dosage anomaly may not be well understood. These findings will be reported as variants of uncertain clinical significance. Any available information about the molecular characteristics of the genetic change and the relationship of the genetic change to phenotype will be included on the report.
  • Parental testing may be recommended in order to classify the result as de novo or familial for the purpose of recurrence risk calculation.

COMPLEMENTARY TESTING:

  • For comprehensive analysis of the genes of interest, it is often indicated to couple gene sequencing with targeted high resolution deletion/duplication analysis.

For assistance determining which testing options are most useful for your patient, please call our laboratory at 402-559-5070 and ask to speak with a laboratory genetic counselor.

REQUIRED FORMS:   Postnatal Test Request Form

OTHER FORMS:   Request for Pre-Authorization for Genetic Testing (Postnatal Diagnoses on peripheral blood)


SPECIMEN COLLECTION & SHIPPING

SPECIMEN REQUIREMENTS:

  • Blood >3 mo of age: 3-5 ml in an EDTA tube (purple top) 
  • Blood (newborn minimum requirement): 1 ml in an EDTA tube (purple top)
  • Buccal swab: kits available upon request
  • Extracted DNA: 5 µg

CPT CODES and PRICING:   Contact the laboratory billing staff for current codes and costs.


TURN-AROUND-TIME:   Results are typically available in 1-2 weeks; 1 week for newborn studies.


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contact us
Phone:  402-559-5070 
1-800-656-3937 x95070
Fax:  402-559-7248
humangenetics@unmc.edu

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