CD8A and Tangier disease: Portuguese hemochromatosis patients with greater iron overload and lower blood CD8 + T-lymphocyte concentrations had a highly conserved ancestral 500 kb microhaplotype on chromosome 6p designated as A-A-T, whereas other patients with milder iron overload and higher blood CD8 + T-lymphocyte concentration had a highly conserved haplotype designated as G-G-G [74].