Natural DNA mixtures generated in fraternal twins in utero

R. J. Rubocki, B. J. McCue, K. J. Duffy, K. L. Shepard, S. J. Shepherd, James Lowell Wisecarver

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Analysis of multiple genetic loci using short tandem repeats (STR) is widely used in human identity testing because the extensive polymorphism at these loci allows for a high degree of discrimination among individuals. We recently received a forensic case that included several pieces of evidence and reference blood samples. Upon initial testing, one of the suspects had a DNA profile that included three alleles at four of the nine loci tested (vWA, FGA, TH01, and D5S818). At each locus, two of the alleles appeared to be "major" alleles with a third "minor" allele present. The profile appeared to be a mixture of two people. Contamination of this first reference sample was suspected and a second, unopened blood specimen was requested from this individual. The DNA profile from this second reference specimen was identical to that of the original specimen at each locus. One of the evidence samples also displayed an identical mixed DNA profile matching that of the reference specimens mentioned above. The relative peak heights of the two "major" and one "minor" allele remained constant in all three samples. Additional background information revealed that the suspect had not received a bone marrow transplant or blood transfusion. However, it was disclosed that this individual is a fraternal (dizygotic) twin. We hypothesize that an exchange of blood cells between the fetuses occurred in utero and that the additional alleles present in these reference samples are derived from cells contributed by his twin sibling. No additional specimens from the suspect or his twin could be obtained for confirmation, and our hypothesis remains untested. Forensic scientists should be aware of this possibility when faced with a DNA profile in which extra alleles at multiple loci are detected.

Original languageEnglish (US)
Pages (from-to)120-125
Number of pages6
JournalJournal of Forensic Sciences
Volume46
Issue number1
StatePublished - Mar 1 2001

Fingerprint

Dizygotic Twins
Alleles
DNA
present
environmental pollution
evidence
Genetic Loci
discrimination
Blood Transfusion
Microsatellite Repeats
Siblings
Blood Cells
Fetus
Bone Marrow
Transplants

Keywords

  • DNA
  • Dizygotic
  • Forensic science
  • Fraternal twins
  • Identity testing
  • Polymerase chain reaction
  • STR
  • Short tandem repeat

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Genetics

Cite this

Rubocki, R. J., McCue, B. J., Duffy, K. J., Shepard, K. L., Shepherd, S. J., & Wisecarver, J. L. (2001). Natural DNA mixtures generated in fraternal twins in utero. Journal of Forensic Sciences, 46(1), 120-125.

Natural DNA mixtures generated in fraternal twins in utero. / Rubocki, R. J.; McCue, B. J.; Duffy, K. J.; Shepard, K. L.; Shepherd, S. J.; Wisecarver, James Lowell.

In: Journal of Forensic Sciences, Vol. 46, No. 1, 01.03.2001, p. 120-125.

Research output: Contribution to journalArticle

Rubocki, RJ, McCue, BJ, Duffy, KJ, Shepard, KL, Shepherd, SJ & Wisecarver, JL 2001, 'Natural DNA mixtures generated in fraternal twins in utero', Journal of Forensic Sciences, vol. 46, no. 1, pp. 120-125.
Rubocki RJ, McCue BJ, Duffy KJ, Shepard KL, Shepherd SJ, Wisecarver JL. Natural DNA mixtures generated in fraternal twins in utero. Journal of Forensic Sciences. 2001 Mar 1;46(1):120-125.
Rubocki, R. J. ; McCue, B. J. ; Duffy, K. J. ; Shepard, K. L. ; Shepherd, S. J. ; Wisecarver, James Lowell. / Natural DNA mixtures generated in fraternal twins in utero. In: Journal of Forensic Sciences. 2001 ; Vol. 46, No. 1. pp. 120-125.
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