Which method is NOT used for DNA-based HLA typing?

The method that is not used for DNA-based HLA typing is Western blotting. HLA (human leukocyte antigen) typing is primarily concerned with identifying specific alleles of the HLA genes, which are important for immune response and tissue compatibility in transplantation. DNA-based methods rely on the use of genetic material for accurate typing.

Western blotting is primarily a protein analysis technique, used to detect specific proteins in a sample through the use of gel electrophoresis and antibody binding. It is not suitable for determining the genetic sequence of DNA or for typing the alleles of HLA genes. In contrast, the other methods listed—RFLP (restriction fragment length polymorphism), bead-bound assays, and sequence-specific PCR (polymerase chain reaction)—are all techniques that involve the manipulation and analysis of DNA, making them appropriate for HLA typing.

RFLP analyzes variations in DNA sequences by cutting the DNA with restriction enzymes and assessing the size of the resulting fragments. Bead-bound assays can detect specific sequences in a multiplex format, allowing for the analysis of multiple HLA types simultaneously. Sequence-specific PCR amplifies specific segments of DNA that correspond to particular HLA alleles, providing a direct and efficient method for typing.