George Herrin

The Frequency of Heteroplasmy in the HVII Region of mtDNA Differs across Tissue Types and Increases with Age

An immobilized sequence-specific oligonucleotide (SSO) probe system consisting of 16 SSO probes that detect sequence polymorphisms within five regions of the mtDNA control region was used to investigate the frequency of heteroplasmy in human mtDNA. Five regions of hypervariable region II (HVII) of the control region were studied in blood-, muscle-, heart-, and brain-tissue samples collected from 43 individuals during autopsy. An initial search for heteroplasmy was conducted by use of the SSO probe system. Samples in which multiple probe signals were detected within a region were sequenced for the HVII region, to verify the typing-strip results. The frequency of heteroplasmy was 5 of 43 individuals, or 11.6%. The frequency of heteroplasmy differed across tissue types, being higher in muscle tissue. The difference in the frequency of heteroplasmy across different age groups was statistically significant, which suggests that heteroplasmy increases with age. As a test for contamination and to confirm heteroplasmy, the samples were sequenced for the HVI region and were typed by use of a panel of five polymorphic nuclear markers. Portions of the tissues that appeared to be heteroplasmic were extracted at least one additional time; all gave identical results. The results from these tests indicate that the multiple sequences present in individual samples result from heteroplasmy and not from contamination.

Isolation of Deoxyribonucleic Acid (DNA) from Saliva and Forensic Science Samples Containing Saliva

Saliva and saliva-stained materials were examined as potential sources of deoxyribonucleic acid (DNA) for DNA analysis and identity testing. In this paper, the authors demonstrate that DNA was isolated and DNA banding patterns suitable for DNA typing were obtained from fresh saliva and various saliva-stained materials, such as envelopes, buccal swabs, gags, and cigarettes. Furthermore, DNA and DNA banding patterns were obtained from actual forensic evidentiary samples containing mixed saliva/semen stains. The DNA banding patterns obtained from saliva or saliva-stained material were indistinguishable from the patterns obtained from blood or hair from the same individual. Intact DNA was readily isolated and DNA banding patterns were obtained from saliva stored at -20 degrees C and dried saliva stains stored under varying conditions. We conclude that saliva and saliva-stained material can be good sources of DNA for analysis and for DNA typing in certain forensic settings.

Evaluation of the AmpliType® PM DNA Test System on Forensic Case Samples

Evidence material from sexual assault cases which had been submitted to the laboratory for routine processing were examined to determine the usefulness of the AmpliType® PM PCR Amplification and Typing Kit developed by Roche Molecular Systems for forensic evidence. In all cases in which a conclusive answer was reached for the AmpliType PM system, the results agreed with or surpassed results previously obtained with RFLP testing. The AmpliType PM DNA test system has promise as a quick and easy method for elimination or inclusion of suspects.

A SIMPLIFIED AMPLIFICATION PROCEDURE FOR TWO REGIONS OF THE GLYCOSYL TRANSFERASE (ABO BLOOD GROUP) GENE

The ability to classify the ABO blood group of physiological stains has been an important tool for forensic scientists. A streamlined method for the determination of glycosyl transferase (ABO) genotypes using PCR amplification is described and validated here. Successful amplification and typing is possible with 1-2 ng template DNA. Concordance studies with samples of known types and nonprobative forensic casework samples were performed. Bloodstains from a single individual from one case produced results discrepant from those obtained by conventional serological ABO typing. All other samples produced results in complete agreement with expected ABO phenotypes. The method described here is relatively simple to perform, requires minimal template DNA and can be completed in less than one day.

Use of Deoxyribonucleic Acid (DNA) Fingerprints for Identity Determination: Comparison with Traditional Paternity Testing Methods—Part II

Six red blood cell (RBC) antigen systems, coupled with human lymphocyte antigen (HLA) phenotyping, were used to establish paternity on 28 mother/child/alleged-father trios. Samples were subsequently examined using the deoxyribonucleic acid (DNA) fingerprinting test with the multilocus Jeffreys DNA probes 33.6 and 33.15. In 27 of 28 paternity cases, the DNA fingerprinting test results supported and enhanced the results of RBC and HLA typing by resolving disputed paternity cases conclusively. One discrepancy between conventional serological methods and DNA analysis is discussed.

Deduction of the Order of Sexual Assaults by DNA Analysis of Two Condoms

Differential DNA extraction procedures were performed on two condoms found at a rape scene. One of the condoms was recovered intact (A), while the second condom (B) had apparently ruptured during the alleged attack. Two related suspects (cousins 1 & 2) were identified as the potential semen donors. Condom B contained DNA from the female and from one of the suspects. Condom A contained DNA from the suspect identified on condom B and from an unidentified individual. The presence of DNA from suspect 2 on both condoms led to the deduction that his sexual activity preceded that of the unidentified suspect. The ability to determine such a sequence of events using DNA typing is unusual.

American Forensic Roundtable: Progress, Status, and the Future

ABSTRACT In February 2014, a group of forensic experts was convened to discuss current topics in the profession. The topics ranged from progress since the National Research Council report in 2009, to education and training, certification, research, and other professional issues, including ethics. This transcript, which represents the dynamic interaction of the participants, has been edited for clarity and length.