HLA-DRB1 and hematocrit: In the Greek population, the frequencies of HLA-DRB1*04:05, -DQB1*02:01, -DQB1*03:02, and -DQA1*03:01 were significantly higher in the group of 125 HT patients than those in the control group with 500 healthy individuals, while the frequency of HLA-DRB1*07, -DQB1*05:02 and -DQB1*06:04 were significantly lower [64].