RESUMO
BACKGROUND: We describe two case studies in the antenatal setting where human immunodeficiency virus (HIV) antibody results were discrepant in serial sera. Root cause analysis including genomic DNA fingerprinting was performed. OBJECTIVE: To analyze serial sera with HIV antibody discrepant results using genomic DNA "finger-printing" to determine whether the sera were from the same or different individuals. STUDY DESIGN: In case study 1, two serial sera with HIV antibody discrepant results, supposedly from a pregnant lady were subjected to root cause analysis. In case study 2, four serial sera 'from' a pregnant lady were subjected to root cause analysis. All sera were analyzed forensically using genomic DNA (gDNA) fingerprinting. In the case study 1, public health look-back exercise was done prior to forensic analysis unlike case study 2, when it was planned for later. RESULTS: Case study 1 gDNA results showed that both sera had identical genotypes and sex indicating that these were from the same individual and that the problem was within automated serum separator pipette syringe. Case study 2 gDNA analysis showed that the 3 of 4 sera were from three different unrelated females indicating an intentional sample mix-up. CONCLUSIONS: Forensic gDNA "finger-printing" in diagnostic virology changed the direction of the investigations; one pointing to a laboratory issue and the other to an intentional deception by the patient. We recommend considering gDNA fingerprinting in any sample discrepancy investigation prior to any public health investigation. This is the first reported use of gDNA analysis in diagnostic virology.