China

Genetic testing is highly recommended before carbamazepine is administered to patients from China, due to high risk for carrying HLA-B*1502. Patients carrying HLA-B*1502 are at strongly increased risk for life treatening carbamazepine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Prevalence of  HLA-B*1502 is high in several Asian countries, including China.
The first report stated (Han-Chinese living in Taiwan): The odds ratio if positive for HLA-B*1502 for developing carbamazepine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis was 2504 (95% CI: 126−49,522) (Ferrel, 2008). Later a systematic review yielded a summary odds ratio of 115.32; (95% CI, 18.17-732.13) among Han-Chinese. (Tangamornsuksan et al., 2013).

See also: Special topics.

Haloperidol plasma concentrations after equal oral dose administration are 40 to 50% higher in Chinese patients compared to Caucasian, Afro-American and Hispanic Americans. Likewise: to achieve similar haloperidol plasma levels the Chinese patients required lower doses (40-50% less) compared to Caucasians and Afro-American patients (Jann, 1992)

There is an association (odds ratio: 4.98, 95% confidence interval 1.43–17.28; P < 0.05) between the human leukocyte antigen HLA-B*1502 allele and lamotrigine-induced Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) in Han Chinese subjects. The HLA-B*1502 allele was present in 33.3% of lamotrigine-induced SJS/TEN patients and in only 9.4% of lamotrigine tolerant patients (Zeng et al. 2015).