Survey of β-Mediterranean anemia (β-TA) prevalence in ethnic minority She of the southwest area in Zhejiang province

Abstract

Objective There are eighty thousand ethnic minority She people in the southwest area of Zhejiang province, which accounts for 12.5 per cent of She in China. Since there is no report on β-TA in She people, this study aimed at exploring the morbidity of β-TA in She population in this area and related hereditary factors. Methods Lishui district were selected, because 70 per cent of the inhabitants were She people. Nineteen counties of Lishui city were included, such as Yunhe county, Jingning county, Suichang county, Songyang county, Longquan county and so on. Five folk primary and high schools and 17 general primary and high schools from forty-two natural villages as well as in Lishui city were surveyed. Ninety per cent of them were located in remote counties. Totally 1 650 cases were sampled by multiple-degree sampling survey, 1 391cases were by total sampling survey and 424 cases were by supplement survey. Totally 3 465 persons were surveyed, among whom 1 561 were males (45.1%), 1 904 were females (54.9%). There were 483 people aged from 0 to 10 years (13.9%), 1 634 aged -20 years (47.2%), 212 aged -30 years (6.1%), 402 aged -40 years (11.6%), 302 aged -50 years (8.7%), and 432 aged -51 years or older (12.5%). The survey process was as follows, firstly, specimen were anti-coagulated by EDTA-K2 reagent and tested for RBC analysis by Counter -JT3 automatic blood cell analyzer. Secondly, the hemoglobin electrophoresis was performed. All the cases were tested with the automatic blood cell analyzer. There were 316 cases with microcytic and/or hypochromic anemia tested by the hemoglobin electrophoresis. Thirdly, 34 of 48 family members from 5 unrelated probands with intermediate advanced congenital β-TA were surveyed for hereditary genealogy. Fourthly, liquids extracted from white blood cells of people who had had survey of hereditary genealogy and part of those with microcytic hypochromic anemia were tested with the methods of reverse-cross testing (RDB) for the type of gene mutation of β-TA and with PCR for the type of gene deficiency of α-TA. Results Among 3 465 inhabitants, 316 cases were found to have microcytic hypochromic anemia, 235 cases were abnormal and diagnosed with the hemoglobin electrophoresis. Of the 211 abnormal cases, 200 cases showed HbA2>3.5%, 35 cases HbF>1%, which indicated that the morbidity in this area was 6.78%. Tested in the same way, there were 18 cases and 6 cases respectively in 34 cases with congenital β-TA, which showed that there was conglomerate family mobility of β-TA . The relationship among HbA2, HbF and MCV in 235 cases with β-TA showed that MCV≤81f l (91.5%) in 215 cases and MCV≥81fl in 20 cases (8.5%). Most of the 20 cases belonged to the congenital β-TA family members, of whom 2 children had advanced β-TA with the history of splenectomy and splenic embolism, respectively. The two children also showed increased MCV, markedly higher RDW (RBC volume distribution width) and abnormal bell-shaped graph for HRD (Histogram RBe volume distribution width) postoperatively. There were 2 992 (86.3%) cases with the intra-ethnic marriage and 473 (13.7%) cases with the She-Han marriage, of whom 227 (7.59%) cases and 8 (1.69%) cases had β-TA, respectively (χ2=22.47, P<0.005). So the intra-ethnic marriage had a higher morbidity of β-TA. The 41 cases with β-TA as the first diagnosis were further analyzed with molecular biology and showed that 4 cases had mutation at -28(A-G)/-28(A-G), 25 cases and 6 cases had-28(A-G)/N and IVS-Ⅱ-654 (C-T)/N, respectively, which showed that there might be two types and three kinds of combinations of the gene mutation in β-TA patients of this area. Conclusion The higher morbidity of β-TA in this area might be related to the intra-ethnic marriage, the conglomerate family mobility and the narrow marriage radius. The type of gene mutation was characterized by transcription mutation and RNA copy mutation. The application of molecular biological analysis could avoid missing stationary type of β-TA. Key words: Beta-Thalasemia; Prevalence Point mutation; Minority groups