β地中海贫血杂合子的特点是小红细胞症和每个红细胞血红蛋白量减少.然而缺失型杂合的(-α/αα)或纯合的(-α/-α)α~+地中海贫血复合β地中海贫血的杂合子,与具有四个完整的α珠蛋白结构基因的β地中海贫血杂合子相比,能产生含有更多血红蛋白量的红细胞,只有少数红细胞指数在正常范围内.根据MCV/MCH值筛检β地中海贫血能够漏掉较多的杂合子.使用渗透脆性试验筛检人群中β地中海贫血亦有少部分呈假阴性. Beta-thalassemia heterozygotes are characterized by microcytic disorder and a decrease in the amount of hemoglobin per erythrocyte whereas deletional heterozygous (-α / αα) or homozygous (-α / -α) α-thalassemia complex β mediterranean Anemic heterozygotes produce red blood cells containing more hemoglobin than only beta thalassemia heterozygotes with four intact alpha-globin structural genes, with only a few red blood cell indices within the normal range.According to the MCV / MCH value sieve Beta-thalassemia can be missed more heterozygotes.There is also a small portion of beta-thalassemia in the population that is screened to be false negative using the Immersion Brittleness Test.