Developmental Validation of a Cannabis Sativa STR Multiplex System for Forensic Analysis

• NCJ Number: 224715
• Journal: Journal of Forensic Sciences Volume: 53 Issue: 5 Dated: September 2008 Pages: 1061-1067
• Author(s): Christopher Howard Ph.D.; Simon Gilmore Ph.D.; James Robertson Ph.D.; Rod Peakall Ph.D.
• Date Published: September 2008
• Length: 7 pages
• Sponsoring Agency: Australian Federal Police; National Drug Law Enforcement Research Fund (NDLERF)
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

This article reports on a developmental validation study conducted on a multiplex system of 10 Cannabis sativa (C. sativa) short tandem repeat (STR) loci, based on recommendations of the Scientific Working Group on DNA Analysis Methods (SWGDAM).

Abstract

Following applicable SWGDAM guidelines, this developmental validation has shown that the set of 10 codominant C. sativa STR loci examined in this study can be routinely and reliably amplified and scored for the multiplex polymerase chain reaction (PCR) conditions tested. Consistent genotypes were obtained from DNA templates in the range of 10.0-1.0 ng, from leaf, root, and stem tissue of C. sativa. Despite success with root and stem tissue as a DNA source, however, the article recommends that where possible the DNA should be obtained from either fresh or air-dried leaf, since this tissue yielded the most consistent results. Leaf tissue is easily sampled, and it is the most reliable source for morphological identification. As anticipated, where DNA is limited there is a risk for allele dropout or overall amplification failure. Where possible, 1.0-10.0 ng of DNA template is recommended for casework analysis of C. sativa with this multiplex system. This study opens the way for internal validation studies within operational forensic laboratories. Given the expectation of some interlaboratory variation in optimal PCR conditions, however, some minor modification of the protocols tested in this study may be useful in subsequent internal validation studies. This article offers recommendations for forensic laboratories planning to adopt these STR markers for forensic analysis of C. sativa. It also highlights some of the issues encountered when applying SWGDAM validation guidelines to plants. The description of the methods used addresses loci and multiplex amplification conditions, tissue source and DNA extraction, the sensitivity study, and fragment detection and genotype analysis. 2 tables, 3 figures, and 32 references