With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: Serious skin reactions such as Stevens–Johnson syndrome or toxic epidermal necrolysis due to carbamazepine therapy are more common in people with a particular human leukocyte antigen allele, HLA-B*1502. Odds ratios for the development of Stevens-Johnson syndrome or toxic epidermal necrolysis (SJS/TEN) in people who carry the allele can be in the double, triple or even quadruple digits, depending on the population studied. HLA-B*1502 occurs almost exclusively in people with ancestry across broad areas of Asia, but has a very low or absent frequency in European, Japanese, Korean and African populations. However, the HLA-A*31:01 allele has been shown to be a strong predictor of both mild and severe adverse reactions, such as the DRESS syndrome form of severe cutaneous reactions, to carbamazepine among Japanese, Chinese, Korean, and Europeans. It is suggested that carbamazepine acts as a potent antigen that binds to the antigen-presenting area of HLA-B*1502 alike, triggering an everlasting activation signal on immature CD8-T cells, thus resulting in widespread cytotoxic reactions like SJS/TEN.
text_B: Would it be out of the ordinary for someone who is of Korean heritage to learn that they have the HLA-B*1502 allele?
YES.