发绀患者，男，29岁，因血氧饱和度低（SaO₂ 89.3%）而超声心动图和胸片正常就诊。取患者的外周血进行血液学一般检查和溶血相关筛查，高效液相色谱技术（high performance liquid chromatography，HPLC）进行血红蛋白（Hb）分析；采用聚合酶链反应和反向点杂交技术检测17种中国人群常见的β-珠蛋白生成障碍性贫血基因突变和非缺失型α-珠蛋白生成障碍性贫血基因突变；采用跨越断裂点聚合酶链反应（gap-polymerase chain reaction，Gap-PCR）法结合琼脂糖凝胶电泳技术检测缺失型α-珠蛋白生成障碍性贫血基因；采用PCR和DNA测序法对α、β珠蛋白基因（HBA1、HBA2与HBB）进行序列分析。患者的血液学一般检查和其他溶血相关检查均无异常发现；HPLC结果显示存在异常Hb 8.1%（位于4.53 min处，S窗），基因分析显示α2-珠蛋白（hemoglobin A2，HBA2）基因c.175C>T，导致α珠蛋白肽链第58位的组氨酸（His）被酪氨酸（Tyr）替换，为杂合型血红蛋白M病（Hb M病）Boston型。Hb M为结构异常的Hb变异体，该异常使血红素铁稳定在氧化状态（Fe³⁺），从而影响Hb的正常释氧功能。该病可能会与引起高铁血红蛋白血症的其他原因混淆，如红细胞高铁血红蛋白还原酶系统的遗传性改变等。该例为中国人群中罕见的Hb M病Boston型，临床呈典型终身发绀表现，预后较好，不需要治疗。

A 29-year-old male with cyanosis had low oxygen saturation (SaO₂ 89.3%) with normal echocardiography and chest X-ray findings. The patient's peripheral blood was analyzed by routine blood analysis and screening tests for hemolysis, and hemoglobin detection was performed by high performance liquid chromatography (HPLC). The polymerase chain reaction (PCR) and reverse dot blot (RDB) technique were used to detect 17 common β-thalassemia gene mutations and non-deletional α-thalassemia in Chinese. Gap-PCR combined with agarose gel electrophoresis was used to detect deletional α-thalassemia. PCR and DNA sequencing for α- and β-globin gene (HBA1, HBA2 and HBB) were simultaneously performed. Both of the routine blood analysis and hemolysis screening tests were with normal findings. The HPLC pattern showed a peak with 8.1% of area at 4.53 min position (S window). Gene analysis showed a heterozygous mutation of HBA2 c.175C>T, Hb M-Boston^{α58 His>Tyr}. Hb M is a kind of Hb with the structural variant that stabilizes heme iron in the oxidized (ferric) state. It can be confused with other causes of methemoglobinemia, like genetic alterations in methemoglobin reductase enzyme systems of red cells. The heterozygotes of Hb M-Boston with typical lifelong cyanosis and good prognosis is really unusual in Chinese population, which does not require any treatment.