TAP 1 and TAP 2 transporter gene polymorphisms in multiple sclerosis: no evidence for disease association with TAP.

Multiple sclerosis (MS) is known to be associated with HLA-DR2, but it is possible that additional major histocompatibility complex (MHC) genes confer disease susceptibility. The most recent candidate genes for MHC-encoded susceptibility are the TAP genes, which are located between the HLA-DQ and DP loci, and encode for proteins believed to transport antigenic peptides from the cytoplasm into the endoplasmic reticulum. We studied TAP 1 and TAP 2 gene polymorphisms in 65 chronic progressive MS patients and 66 healthy subjects. No significant differences in the frequencies of TAP polymorphisms were observed between both groups. These data suggest that TAP is not a susceptibility gene for MS and that the disease-predisposing haplotype does not extend as far as TAP.