123With >1 million patients undergoing coronary stenting per year in the US, this
extrapolates to >14,000 stent thrombosis events per year! Moreover, the meta-anal-
ysis did not test for heterogeneity among patients who underwent stenting versus
those who were medically treated. They pointed out that prior pharmacogenomic
studies on clopidogrel have shown CYP2C19 loss-of-function variants to be impor-
tant in coronary stenting patients and does not show up in those medically treated.
It is obvious that a metal implant in a coronary artery would pose a particular vul-
nerability to inadequate platelet suppression.
Role of Pharmacogenetics in Carbamazepine Therapy
Carbamazepine is responsible for severe ADRs such as Stevens-Johnson syndrome
(SJS) and toxic epidermal necrolysis (TEN) and there is a high incidence of these
ADRs in Taiwan compared to other countries. In 2007, Taiwan’s Department of
Health updated the label for the anticonvulsant drug carbamazepine (CBZ) to warn
patients of a genetic link to potentially serious side effects of CBZ and recommends
testing patients for predisposition to these ADRs. A series of retrospective studies
has shown that the human leukocyte antigen (HLA)-B1502 marker, which is pres-
ent in about 5 % of the Taiwanese population has a very strong association with
these serious ADRs. The updated label notes this risk and warns that a patient who
carries the HLA-B1502 gene will have at least 193 times higher risk of developing
ADR than a patient who is not a HLA-B1502 carrier (Lee et al. 2010 ). Identifi cation
of subjects carrying the HLA-B1502 allele and the avoidance of carbamazepine
therapy in these subjects was strongly associated with a decrease in the incidence of
carbamazepine-induced SJS–TEN (Chen et al. 2011 ).
The presence of the HLA-A3101 allele was associated with carbamazepine-
induced hypersensitivity reactions among subjects of Northern European ancestry.
The presence of the allele increased the risk from 5.0 % to 26.0 %, whereas its
absence reduced the risk from 5.0 % to 3.8 % (McCormack et al. 2011 ).
The strong association between CBZ and HLA-B1502 has prompted the FDA
to update the label for CBZ to include genetic information and to recommend
genetic testing before prescribing CBZ. Patients with Asian ancestry or who are
from regions prevalent in HLA-B*1502 should be screened before CBZ treatment.
Role of Pharmacogenetics in Statin Therapy
Lowering low-density lipoprotein cholesterol with statin therapy results in substan-
tial reductions in cardiovascular events, and larger reductions in cholesterol may
produce larger benefi ts. In 10–20 % of cases, myopathy occurs in association with
statin therapy, especially when the statins are administered at higher doses and with
certain other medications and is a reason for discontinuation. Only half of the
patients remain on statin therapy after starting to use it. A genome wide association
study of patients on simvastatin (Zocor) therapy has identifi ed SNP rs4363657
Role of Pharmacogenetics in Pharmaceutical Industry