Drop-out probabilities of IrisPlex SNP alleles

Research output: Contribution to journalJournal articleResearchpeer-review

  • Jeppe Dyrberg Andersen
  • Torben Tvedebrink
  • Helle Smidt Mogensen
  • Claus Børsting
  • Niels Morling

Abstract

In certain crime cases, information about a perpetrator's phenotype, including eye colour, may be a valuable tool if no DNA profile of any suspect or individual in the DNA database matches the DNA profile found at the crime scene. Often, the available DNA material is sparse and allelic drop-out of true alleles is possible. As part of the validation of the IrisPlex assay in our ISO17025 accredited, forensic genetic laboratory, we estimated the probability of drop-out of specific SNP alleles using 29 and 30 PCR cycles and 25, 50 and 100 Single Base Extension (SBE) cycles. We observed no drop-out when the amount of DNA was greater than 125 pg for 29 cycles of PCR and greater than 62 pg for 30 cycles of PCR. With the use of a logistic regression model, we estimated the allele specific probability of drop-out in heterozygote systems based on the signal strength of the observed allele. The probability of drop-out in heterozygote systems depended on the signal strength of the observed allele as well as the number of PCR and SBE cycles.
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In certain crime cases, information about a perpetrator's phenotype, including eye colour, may be a valuable tool if no DNA profile of any suspect or individual in the DNA database matches the DNA profile found at the crime scene. Often, the available DNA material is sparse and allelic drop-out of true alleles is possible. As part of the validation of the IrisPlex assay in our ISO17025 accredited, forensic genetic laboratory, we estimated the probability of drop-out of specific SNP alleles using 29 and 30 PCR cycles and 25, 50 and 100 Single Base Extension (SBE) cycles. We observed no drop-out when the amount of DNA was greater than 125 pg for 29 cycles of PCR and greater than 62 pg for 30 cycles of PCR. With the use of a logistic regression model, we estimated the allele specific probability of drop-out in heterozygote systems based on the signal strength of the observed allele. The probability of drop-out in heterozygote systems depended on the signal strength of the observed allele as well as the number of PCR and SBE cycles.
Original languageEnglish
JournalForensic Science International: Genetics. Supplement Series
Volume4
Issue number1
Pages (from-to)238-239
Number of pages2
ISSN1875-1768
DOI
Publication statusPublished - 2013
Publication categoryResearch
Peer-reviewedYes
ID: 167526453