**3. History of HLA genotyping methods**

Many variations of the conventional HLA genotyping methods such as incorporating restric‐ tion fragment polymorphisms (RFLP) [36], single strand conformation polymorphism (SSCP) [37], sequence-specific oligonucleotides (SSOs) [38], sequence-specific primers (SSPs) [39], and sequence-based typing (SBT), like the Sanger method [33], have been used for the efficient and rapid HLA matching in transplantation therapy [40–43], research into HLA-related diseases [2, 3], population diversity studies [44–46], and in forensic and paternity testing [47]. The HLA genotyping methods mainly applied today are PCR-SSOP, such as the Luminex commercial methodology [48, 49], and SBT by the Sanger method employing capillary sequencing based on chain–termination reactions [33, 34]. However, both methods often detect more than one pair of unresolved HLA alleles because of chromosomal phase (*cis/trans*) ambiguity [50, 51]. To solve the phase ambiguity problem, new HLA genotyping technologies have been reported and commercialized that combine the PCR amplification of targeted HLA genomic regions with NGS platforms such as the ion PGM system (Life Technologies), GS Junior system (Roche), and the MiSeq system (Illumina) [52}. The PCR/NGS methods are expected to produce genotyping results that detect new and null alleles efficiently without phase ambiguity.
