• Test Code:
    6620
  • Department:
    Constitutional Cytogenetics
  • Test Synonyms:
    Chromosome Instability • Roberts syndrome
  • CPT Code(s):
    88237 • 88249
Background:

Premature sister chromatid separation is a manifestation of chromosome instability.  This test will also detect the premature centromere separation observed in Roberts syndrome, one of the cohesinopathies.  Roberts syndrome patients have mutations in a gene involved in sister chromatid cohesion.  Their metaphase chromosomes show spontaneous repulsion of centromeres and a railroad track appearance to their chromosomes.  There is clinical overlap with other genomic instability syndromes, such as Fanconi anemia.  Fanconi anemia is distinguished by increased breakage and radial formations, sometimes spontaneous.  These chromosomal states would also be observed in this test.

Methodology:

Cells from blood are cultured for 72 to 96 hours.  Skin biopsies are set up in culture flasks and maintained until there are an adequate number of cells, usually 7-10 days.  Metaphase chromosomes are prepared and stained with Wright stain.  Fifty metaphase cells are scored for premature centromere separation.  Should increased breakage or radial formation be observed, these findings would be noted.

Specimen Requirements:

Blood:  

  • Adult - 3-5 mL drawn into a GREEN top sodium heparin vacutainer tube or into a pre-heparinized plastic syringe (use 0.2 cc sodium heparin, 1000 unit/mL).  Do NOT use lithium heparin.
  • Child - 1-2 mL, as above.
  • Infant - 1-2 mL, as above. 
  • Keep at room temperature and transport to laboratory as soon as possible.
  • Contact Client Services at (855) 535-1522 for supplies and instructions.

Skin:

  • 3 mm full thickness skin biopsy obtained under sterile conditions or
  • Two T-25 flasks of cultured fibroblasts

Skin biopsy specimens must be suspended in sterile culture media (RPMI or DMEM) or non-bacteriostatic normal saline in a sterile container and shipped at ambient temperature by express overnight delivery. DO NOT REFRIGERATE OR FREEZE!

A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES.  Please include detailed clinical information,        including ethnicity, clinical history, and family history.

Test Performed (Days):

Mon-Sat

Turn Around Time:

7-14 Days, depending on tissue source

Shipment Sensitivity Requirements:

  • Keep specimen at room temperature during transit. 
  • Do not use the cold pack provided in the KDL shipping kit. 
  • Ship the specimen overnight express, using the FedEx priority overnight label provided. 
  • The specimen must arrive at the lab no more than 24 hours after collection.

References:

  1. Gerkes EH, van der Kevie-Kersemaekers A-MF, Yakin M, Smeets DFCM, van Ravenswaaij-Arts, CMA: The importance of chromosome studies in Roberts syndrome/SC phocomelia and other cohesinopathies.  Eur J Med Genet. 53:40-44, 2010.

  2. van der Lelij P, Oostra AB, Rooimans MA, Joenje H, de Winter JP: Diagnostic overlap between Fanconi anemia and the cohesinopathies: Roberts syndrome and Warsaw breakage syndrome.  Anemia. Volume 2010, Article ID 565268, 7 pages, doi:10.1155/2010/565268.

Additional Info:

After hours, please leave message at (855) 535-1522 for cytogeneticist on call.

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