CD4 and heterotaxy, visceral, 5, autosomal: However, the M2 MHC haplotype has also been associated with significant control of chronic phase SIV viremia [49], yet we failed to detect significant CD4+ or CD8+ T cell cytokine responses against HIV-1 F4 peptides in the M2/M3 heterozygote F54, despite two immunisations.