Analysis of Ambiguities of HLA-B Typing using the Dynal RELI(TM) SSO HLA-B Test and Development of an`Interpretation Program for Koreans'

Roh, Eun Youn; Park, Sungkeun; Kim, Hyun Soo; Park, Hyejin; Lim, Young Mi; Han, Bok Youn; Park, Myoung Hee

Abstract

BACKGROUND
In recent years, DNA typing has been increasingly used in HLA-A and B typing, and commercial kits based on the PCR-SSO method are most commonly used in Korea. However, SSO typing kits show ambiguities to some extent in the generic level typing of HLA-B alleles. We analyzed the ambiguities in the Dynal RELI(TM) SSO HLA-B test (Dynal B test) with confirmatory typing results, and developed and evaluated the accuracy and efficacy of an `Interpretation Program for Koreans'. METHODS: A total of 2, 169 Korean marrow donor registry samples were typed for HLA-B alleles using the Dynal B test (56 probes) and all of the 222 cases showing ambiguities were subjected to confirmatory typing. We have developed an `Interpretation Program for Koreans' for the Dynal B test on the basis of the allele frequencies of Korean, Japanese and Asian populations. The samples showing ambiguities in the Dynal B test were interpreted using the `Interpretation Program for Koreans' and the results were compared with confirmatory typing results. RESULTS: The Dynal B test showed 10.2% (222/2, 169) of ambiguities and these ambiguities were classified into 47 different band patterns. These ambiguity patterns were interpreted using the `Interpretation Program for Koreans', which showed ambiguities in 14 band patterns and 3.4% (73/2, 169) of the total samples. Among these ambiguities, 4 band patterns (55 samples) arose from those alleles which are not found in Koreans and rarely found in Japanese or Asians (B*1522, *3521, *7802). Thus, excluding these rarities, only less than 1% (18/2, 169) of samples resulted in ambiguities, and most (16/18) of these were B55 vs. B56 ambiguities. The results from the `Interpretation Program for Koreans' were fully concordant with the confirmatory typing results. CONCLUSIONS: The Dynal B test showed around 10% ambiguities and the `Interpretation Program for Koreans' showed 3.4% of ambiguities. Excluding the ambiguities with extremely low probabilities arising from rare alleles in Japanese or Asians, actually >S99% of the samples could be typed accurately using the program without additional confirmatory tests.