广西地区α2珠蛋白基因密码子30缺失导致非缺失型血红蛋白H病

目的　分析广西地区血红蛋白 (hemoglobin,Hb) H病的基因型 ,了解其表型与基因型的相互关系。方法　对 2 98个病例进行血液学分析、血红蛋白分析 ,及用聚合酶链反应方法和 DNA测序确诊基因突变。结果　在 2 98例 Hb H病患者中发现 1例罕见的 Hb H病。患者为男性 ,2 5岁。自幼有黄疸、脾肿大 ,从未输过血。血液学分析示血红蛋白 10 7g/ L,RBC4 .9× 10 1 2 / L,MCV76 .2 fl,血红蛋白分析 Hb H Hb Bart's34.4 1%。基因分析证实其为 α2珠蛋白基因密码子 30缺失复合东南亚缺失型 α地中海贫血 - 1。结论　我国曾报道的非缺失型 Hb H病主要有 Hb CS- H,Hb QS- H及 α2珠蛋白基因密码子 31基因突变复合东南亚缺失型 α地中海贫血 - 1,临床上表现为中至重度贫血的非缺失型 Hb H病。与之不同的是 ,该患者无贫血 ,但 Hb H Hb Bart's水平高于上述疾病。此基因突变在 α地中海贫血高发区之一的广西地区的认识和发现 ,对该地区的遗传咨询和产前诊断具有重要意义。

α2 codon 30 deletion (△GAG) causing nondeletional hemoglobin H disease in Guangxi province

OBJECTIVE: To analyze genotypic profiles and understand the relationship between the genotype and phenotype of Hb H disease in Guangxi province. METHODS: Hematologic and Hb analyses on the cases were performed to detect their alpha thalassemia genotypes using PCR method and DNA sequencing. RESULTS: An unusual case was identified in one of the 298 patients with Hb H disease diagnosed in the First Affiliated Hospital of Guangxi Medical University from October 2002 to November 2003. The 25-year-old male patient, a native of Yulin in Guangxi province, had had jaundice and splenomegaly since childhood, and he had never received blood transfusion. Hematologic examinations revealed his hemoglobin 107 g/L, RBC 4.9+10(12) g/L, MCV 76.2 fl, MCH 21.8 pg, MCHC 287 g/L, HCT 0.373, reticulocyte 3%. Hb analysis showed the level of Hb H + Hb Bart's 34.41%. PCR and DNA sequencing confirmed the genotype of a deletion at codon 30 of alpha2 globin gene and SEA alpha-thalassemia-1. CONCLUSION: This unusual case had no anemia, but had higher level of Hb H and Hb Bart's when compared to those non-deletional Hb H disease cases such as Hb CS-H, HbQS-H and alpha2 codon 31 mutation combined with SEA alpha-thalassemia-1 previously reported in mainland China. The discovery and recognition of this gene mutation and related genotype and phenotype is of importance to the genetic counseling and prenatal diagnosis in Guangxi province where the incidence of alphathalassemia is very high.