Volume 39, Issue 1 (January 1994)

    Analysis and Interpretation of the HLA DQα “1.1 Weak-Signal” Observed During the PCR-Based Typing Method

    (Received 10 December 1992; accepted 22 June 1993)

    CODEN: JFSOAD

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    Abstract

    The Perkin-Elmer (PE) AmpliType DQα Forensic Kit is currently available for amplification and typing of a polymorphic region in the Human Leukocyte Antigen (HLA) DQα DNA sequence. Following amplification of the DQα region with the PE kit, typing strips are processed. These strips contain immobilized DNA probes designed to distinguish six possible HLA DQα alleles. It has been observed in this laboratory and others that in a single source DNA sample, it is possible to detect a weak signal on the 1.1 specific allele dot when the samples' genotype clearly does not contain the 1.1 allele. It has been suggested that a potential source of this weak-signal is the non-specific amplification of a HLA DXα gene sequence. To demonstrate the relationship of the DXα gene to the 1.1 non-specific signal, we designed biotinylated DXα PCR primers specific for a 178 bp region in which the amplified product spans the homologous DQα region encompassing the DNA probes present on the typing strips. DXα DNA sequences from various DQα genotypes were amplified and hybridized to DQα typing strips. We have demonstrated that DXα PCR products do not always hybridize to the 1.1 probe on the typing strips. Sequence analysis of DXα PCR products show that this region is polymorphic which may explain why the occurrence of the “1.1 weak-signal” is unpredictable. We have further analyzed the effect of DNA template concentration for the DQα amplification protocol and have shown that regulation of PCR input DNA optimizes the amplification and typing protocols for HLA DQα alleles and minimizes the potential observation of the “1.1 weak-signal.”


    Author Information:

    Caraballo, BK
    Forensic Scientist and Serology Supervisor, Palm Beach County Sheriff's Crime Laboratory, West Palm Beach, FL

    Crouse, CA
    Forensic Scientist and Serology Supervisor, Palm Beach County Sheriff's Crime Laboratory, West Palm Beach, FL

    Vincek, V
    Assistant Professor, University of Miami School of Medicine, Miami, FL


    Stock #: JFS13569J

    ISSN: 0022-1198

    DOI: 10.1520/JFS13569J

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    Title Analysis and Interpretation of the HLA DQα “1.1 Weak-Signal” Observed During the PCR-Based Typing Method
    Symposium , 0000-00-00
    Committee E30