Hb I-Toulouse in association with homozygosity for the α3.7 deletion in a Pacific Island woman

Abstract

Only four cases of Hb I-Toulouse have been reported to date. Current literature associates Hb I-Toulouse in the heterozygote with a mild chronic hemolytic anemia. The variant is mildly unstable with a tendency to form metHb. The quantity of the variant in heterozygotes has been reported as varying between 33 to 40%. This report confirms the finding from a single case, that a reduced percentage of Hb IToulouse along with microcytosis can be attributed to the co-inheritance of an abnormal α globin genotype. This current case was found in a woman of Pacific People ethnicity residing in New Zealand. There is a high prevalence of α thalassemia in this ethnic group and New Zealand has the highest Pacific population in the world. Therefore, if a reduced percentage of Hb I-Toulouse is found with microcytosis and normal iron studies, co-inheritance with α thalassemia should be considered. 目前仅有四例Hb I-Toulouse的病例报告。 当前的文献将杂合子中的Hb I-Toulouse与慢性溶血性贫血相关联。 这种变异体轻度不稳定，有形成高铁血红蛋白（metHb）的倾向。 杂合子中变异体数量据报道为33%至40%不等。 本报告证实从单一病例得到的结果，即伴有小红细胞症的更低Hb I-Toulouse百分比可被归结为异常α球蛋白基因型的合并遗传。 该例当前病例在一名居住在新西兰的太平洋诸岛族裔女性身上发现。 在这个族群中存在较高的α地中海贫血患病率，而在全世界新西兰的太平洋诸岛族裔人口最多。 因此，如果发现Hb I-Toulouse的百分比更低，同时伴有小红细胞症并且检查铁含量正常，则应考虑α地中海贫血的合并遗传。