title: DNA Yield From Tissue Samples in Surgical Pathology and Minimum Tissue Requirements for Molecular Testing.
abstract: BACKGROUND
  Complex molecular assays are increasingly used to direct therapy and provide diagnostic and prognostic information but can require relatively large amounts of DNA.
  
  
  OBJECTIVE
  To provide data to pathologists to help them assess tissue adequacy and provide prospective guidance on the amount of tissue that should be procured.
  
  
  METHODS
  We used slide-based measurements to establish a relationship between processed tissue volume and DNA yield by A260 from 366 formalin-fixed, paraffin-embedded tissue samples submitted for the 3 most common molecular assays performed in our laboratory (EGFR, KRAS, and BRAF). We determined the average DNA yield per unit of tissue volume, and we used the distribution of DNA yields to calculate the minimum volume of tissue that should yield sufficient DNA 99% of the time.
  
  
  RESULTS
  All samples with a volume greater than 8 mm(3) yielded at least 1 μg of DNA, and more than 80% of samples producing less than 1 μg were extracted from less than 4 mm(3) of tissue. Nine square millimeters of tissue should produce more than 1 μg of DNA 99% of the time.
  
  
  CONCLUSIONS
  We conclude that 2 tissue cores, each 1 cm long and obtained with an 18-gauge needle, will almost always provide enough DNA for complex multigene assays, and our methodology may be readily extrapolated to individual institutional practice.
authors.affiliation: From the Department of Laboratory Medicine, University of Washington Medical Center, Seattle. Dr Austin is now with the Department of Pathology, Walter Reed National Military Medical Center, Bethesda, Maryland.
authors.forename: Melissa C
authors.initials: MC
authors.lastname: Austin
authors.forename: Christina
authors.initials: C
authors.lastname: Smith
authors.forename: Colin C
authors.initials: CC
authors.lastname: Pritchard
authors.forename: Jonathan F
authors.initials: JF
authors.lastname: Tait
mesh_terms: D001706:Biopsy / Q000379:methods*; D004247:DNA / Q000032:analysis / Q000302:isolation & purification*; D004252:DNA Mutational Analysis / Q000379:methods*; D006801:Humans; D010340:Pathology, Surgical / Q000379:methods*; D012189:Retrospective Studies
chemical_list: D004247:DNA