HLA-B locus sequence-based typing.

We describe an approach for HLA-B high-resolution typing. A single locus-specific amplification generates a 1-kb fragment useful for direct sequencing. Four internal primers are necessary for exon 2 and 3 cycle-sequencing in both directions. Fluorescent dye-labelled nucleotides are incorporated during cycle-sequencing and reaction products are analyzed in an automated DNA sequencer. At present, software programs allow automatic assignment of exon 2 only; analysis of exon 3 is not automatic. In the future, the development of more sophisticated software will improve allele assignment. The approach described in this work offers a precise and efficient identification of known allele sequences and at the same time can differentiate new alleles. Furthermore, it may be applied as a model for the development of similar molecular typing approaches for other polymorphic HLA loci.