The observed differences could be explained by involvement of another genetic factor linked with
HLA complex (MICA, TNF) subdividing the DQA1-DQB1 haplotypes in different at-risk subhaplotypes, some being more at risk than others [28-30].
(1-3) As an important gene cluster related to immune system function in humans, different genotypes of
HLA complex may influence the susceptivity and repellency of drug use combined with HIV infection.
The
HLA complex in biology and medicine; a resource book.
The challenge is now to identify the location within or outside the
HLA complex that underlies this genetic association or associations, and to determine whether the genetic change is required to be present on both of the pair of chromosomes (known as recessive homozygosity).
"We already know about the
HLA complex, one group of genes that is known to predispose people to rheumatoid arthritis in particular and autoimmunity in general," Dr.
About 224 gene loci were described out of 3.6 Mbp
HLA complex super-locus [6].
The major genetic determinants are the DR3 and DR4 alleles (or variants) of a group of genes called the
HLA complex. The strongest risk occurs when these risk alleles occur in pairs which can either be homozygous (DR3/DR3 or DR4/DR4), or compound heterozygous (DR3/DR4) genotypes.