Hemoglobin E-thalassemia: a study of 16 cases

Few reports of hemoglobin E/beta-thalassemia in Northeast India: underdiagnosis or complete exclusion of beta-thalassemia by hemoglobin E

PURPOSE

India bears a major burden of homozygous beta-thalassemia. Hemoglobin (Hb) E/beta-thalassemia has been described mainly among Bengalis in Eastern India. Ethnic groups in northeastern India have among the highest known gene frequency for Hb E. However, there are few reports of Hb E/beta-thalassemia from these ethnic groups. This study aims to determine whether the paucity of reports of Hb E/beta-thalassemia from this region are because of underdiagnosis or complete elimination of beta-thalassemia by Hb E.

POPULATIONS AND METHODS

The published literature concerning Hb E, beta-thalassemia, and the syndrome of Hb E/beta-thalassemia in Indid, Tibeto-Burman, and Austro-Asiatic ethnic groups in northeast India was analyzed to determine the gene frequency of Hb E and beta-thalassemia for different ethnic groups. The expected cases of Hb E/beta-thalassemia were calculated using the Hardy-Weinberg law.

RESULTS

The Bodo-Kachari have a gene frequency of 0.50 for Hb E, the highest anywhere in the world. There are, however, no reports of beta-thalassemia in this group. Among ethnic groups in which prevalence of Hb E and beta-thalassemia are known, there is a vast discrepancy between the reported number of cases of Hb E/beta-thalassemia and the number predicted by Hardy-Weinberg law. Thus, there are only seven cases of Hb E/beta-thalassemia from northeast India reported in the literature as opposed to 67,332 predicted cases.

CONCLUSION

A potentially large pool of unsuspected Hb E/beta-thalassemia cases exist in northeast India. The significance of this finding and possible contributory factors are discussed.

Anemia and hemoglobinopathies in Southeast Asian refugee children

Hematologic evaluations of 254 Southeast Asian refugee children from 163 families are reported. Hemoglobin E trait was common in Cambodians (19%) and Laotians (18%), but rare in Vietnamese (1%). beta-Thalassemia trait was most prevalent in Vietnamese (8%), and less common in Cambodians and Laotians (3%). alpha-Thalassemia was prevalent in all three groups. Hemoglobin concentrations and mean corpuscular volumes seen with hemoglobinopathies were compared with those of Southeast Asian children with normal hemoglobin. Both Hb AE and Hb EE were shown to be benign conditions resulting in microcytosis and mild, if any, anemia. In children with Hb AE, mean corpuscular volume ranged from 64 to 78 ft and Hb E from 27% to 34%. In those with Hb EE, microcytosis was more marked (50 to 63 ft). In 15 children with Hb EE, there was a delayed fall in fetal hemoglobin, which can cause diagnostic difficulties in infants.

The laboratory evaluation of microcytic red blood cells

Microcytic red blood cell states are common clinical problems in both adult and pediatric age groups. The recent widespread availability of electronic blood cell counters for performing routine blood counts has increased the detection of microcytic red blood cells. Physicians must workup both symptomatic and asymptomatic patients with microcytic red blood cells before they can initiate proper therapy and/or counseling. The purpose of this review is threefold: (1) to discuss the causes of microcytic red blood cells in terms of disorders of decreased heme production vs. disorders of decreased globin production, (2) to review the clinical laboratory tests useful in differentiating microcytic red blood cell states, and (3) to present a practical approach for the laboratory workup of microcytic red blood cells.