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 drugs 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.
Norco may refer to:

Places
Norco, California, U.S.
Norco Hills, or La Sierra Heights, section of the Temescal Mountains
Norco, Louisiana, U.S.

Other uses
Norco Bicycles, a Canadian bicycle manufacturer
Norco Co-operative, an agricultural supply and marketing co-operative, New South Wales, Australia
Northern Co-operative Society (Norco), a defunct Aberdeen, Scotland co-operative society
Norco, a brand name for the fixed-dose combination opioid pain medication hydrocodone/paracetamol
NORCO (video game), a point-and-click video game set in a fictional version of Norco, Louisiana

See also
Norco shootout