史蒂芬斯－強森症候群
Stevens–Johnson syndrome

context: zh_tw: 史提芬強生症候群是一種罕見疾病，每年大約有 1,000,000 分之 2.6 至 6.1 個個案。在美國，每年大約有 300 個新症。比較兒童，情況較多發生於成人，而女性較男性普遍，兩性的比例為 3:2。
en: SJS is a rare condition, with a reported incidence of around 2.6 to 6.1 cases per million people per year. In the United States, about 300 new diagnoses are made each year. The condition is more common in adults than in children.
qas: question: zh_tw: 哪裡每年有 300 個史提芬強生症候群新症？
en: Where are 300 new cases of SJS found each year?
answers: zh_tw: text: 美國
en: text: United States

context: zh_tw: 在一些東亞人口研究 (漢人與泰人)，卡馬西平（Carbamazepine）和苯妥英鈉（Phenytoin）與 HLA-B*1502 (HLA-B75) 會導致史提芬強生症候群有強烈的反應，HLA-B serotype 較寬闊 serotype HLA-B15。一項在歐洲的研究建議指出指標基因 (Genetic marker) 只是與亞洲東部的人有關。根據亞洲人的發現，在歐洲進行相似的研究顯示 61% 的黃嘌呤誘導史提芬強生症候群 / 中毒性表皮壞死病患者帶有 HLA-B58 (B*5801 對偶基因 - 歐洲人的顯性頻率具代表性地有 3%)。一項研究推斷 "即使當 HLA-B 等位基因表現是高風險因素，至於別嘌醇，它們既不充分也不必要的去解釋疾病。"
en: SJS is a type IV hypersensitivity reaction in which a drug or its metabolite stimulates cytotoxic T cells (i.e. CD8+ T cells) and T helper cells (i.e. CD4+ T cells) to initiate autoimmune reactions that attack self tissues. In particular, it is a type IV, subtype IVc, delayed hypersensitivity reaction dependent in part on the tissue-injuring actions of natural killer cells. This contrasts with the other types of SCARs disorders, i.e., the DRESS syndrome which is a Type IV, Subtype IVb, hypersensitivity drug reaction dependent in part on the tissue-injuring actions of eosinophils and acute generalized exanthematous pustulosis which is a Type IV, subtype IVd, hypersensitivity reaction dependent in part on the tissue-injuring actions of neutrophils.Like other SCARs-inducing drugs, SJS-inducing drugs or their metabolites stimulate CD8+ T cells or CD4+ T cells to initiate autoimmune responses. Studies indicate that the mechanism by which a drug or its metabolites accomplishes this involves subverting the antigen presentation pathways of the innate immune system. The drug or metabolite covalently binds with a host protein to form a non-self, drug-related epitope. An antigen presenting cell (APC) takes up these alter proteins; digests them into small peptides; places the peptides in a groove on the human leukocyte antigen (i.e. HLA) component of their major histocompatibility complex (i.e. MHC); and presents the MHC-associated peptides to T-cell receptors on CD8+ T cells or CD4+ T cells. Those peptides expressing a drug-related, non-self epitope on one of their various HLA protein forms (HLA-A, HLA-B, HLA-C, HLA-DM, HLA-DO, HLA-DP, HLA-DQ, or HLA-DR) can bind to a T-cell receptor and thereby stimulate the receptor-bearing parent T cell to initiate attacks on self tissues. Alternatively, a drug or its metabolite may stimulate these T cells by inserting into the groove on a HLA protein to serve as a non-self epitope or bind outside of this groove to alter a HLA protein so that it forms a non-self epitope. In all these cases, however, a non-self epitope must bind to a specific HLA serotype (i.e. variation) in order to stimulate T cells. Since the human population expresses some 13,000 different HLA serotypes while an individual expresses only a fraction of them and since a SJS-inducing drug or metabolite interacts with only one or a few HLA serotypes, a drug's ability to induce SCARs is limited to those individuals who express HLA serotypes targeted by the drug or its metabolite. Accordingly, only rare individuals are predisposed to develop a SCARs in response to a particular drug on the bases of their expression of HLA serotypes: Studies have identified several HLA serotypes associated with development of SJS, SJS/TEN, or TEN in response to certain drugs. In general, these associations are restricted to the cited populations.In some East Asian populations studied (Han Chinese and Thai), carbamazepine- and phenytoin-induced SJS is strongly associated with HLA-B*1502 (HLA-B75), an HLA-B serotype of the broader serotype HLA-B15. A study in Europe suggested  the gene marker is only relevant for East Asians. This has clinical relevance as it is agreed upon that prior to starting a medication such as allopurinol in a patient of Chinese descent, HLA-B*58:01 testing should be considered.Based on the Asian findings, similar studies in Europe showed 61% of allopurinol-induced SJS/TEN patients carried the HLA-B58 (phenotype frequency of the B*5801 allele in Europeans is typically 3%). One study concluded: "Even when HLA-B alleles behave as strong risk factors, as for allopurinol, they are neither sufficient nor necessary to explain the disease."Other HLA associations with the development of SJS, SJS/TEN, or TEN and the intake of specific drugs as determined in certain populations are given in HLA associations with SCARs.
qas: question: zh_tw: 藥物反應的關聯通常僅限於誰？
en: Associations in drug responses are often restricted to who?
answers: zh_tw: text: 人口
en: text: cited populations