title: Evaluation of the long-term storage stability of saliva as a source of human DNA.
abstract: OBJECTIVE
  The objectives of this paper are to determine the storage stability of saliva at 37 °C over an 18-month period, and its influence on the DNA yield, purity, PCR protocols and genotyping efficacy.
  
  
  METHODS
  Of the 60 participants, blood samples were obtained from 10 and saliva from 50. Samples were subjected to different storage conditions: DNA extracted immediately; DNA extracted following storage at 37 °C for 1, 6, 12 and 18 months. Subsequently, DNA yield, OD(260/280) and OD(260/230) ratios were measured. The isolated DNA was used to amplify exons 0-7 of the RUNX2 gene and subsequently sequenced. Furthermore, 25 SNPs were genotyped.
  
  
  RESULTS
  The mean DNA yield, OD(260/280) and OD(260/230) ratios obtained from blood were 67.4 ng/μl, 1.8 ± 0.05 and 1.8 ± 0.4 respectively. DNA yield obtained from saliva was significantly higher than blood (p < 0.0001), ranging from 97.4 to 125.8 ng/μl while the OD(260/280) ratio ranged from 1.8 ± 0.13 to 1.9 ± 0.1. The success rates for the 25 SNPs ranged from 98 to 100 % for blood and 96-99 % for saliva samples with the genotype frequencies in Hardy-Weinberg equilibrium (>0.01).
  
  
  CONCLUSIONS
  Saliva can be stored at 37 °C for 18 months without compromising its quality and ability to endure genetic analyses.
  
  
  CONCLUSIONS
  Saliva is a viable source of human DNA to facilitate the feasibility of large-scale genetic studies.
authors.affiliation: Paediatric Dentistry, School of Dentistry, The University of Western Australia, Perth, Australia. robert_prashanth@yahoo.com
authors.forename: Robert P
authors.initials: RP
authors.lastname: Anthonappa
authors.forename: Nigel M
authors.initials: NM
authors.lastname: King
authors.forename: A Bakr M
authors.initials: AB
authors.lastname: Rabie
mesh_terms: D002648:Child; D002675:Child, Preschool; D004247:DNA / Q000235:genetics / Q000302:isolation & purification*; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D012463:Saliva / Q000737:chemistry*; D013048:Specimen Handling / Q000379:methods*; D013696:Temperature
chemical_list: D004247:DNA