Department of Clinical Pathology, Faculty of Medicine, Assiut University, Assiut Governorate, Egypt.
National Haemoglobinopathy Reference Laboratory, Oxford Radcliffe Hospitals National Health Service Trust, Oxford, Oxfordshire, UK.
Hemoglobin. 2020 Nov;44(6):442-445. doi: 10.1080/03630269.2020.1850473. Epub 2020 Nov 29.
Hb Manitoba [α102(G9)Ser→Arg] is a rare α chain variant with diverse ethnic origins. It is mildly unstable with an expression of around 10.0-14.2% in the heterozygous state in most literature. In this study, 12 cases of Hb Manitoba [11 cases carried Hb Manitoba II (: c.309C>A) and one case carried Hb Manitoba IV (: c.307A>C)] were detected during a wide-spectrum study of α chain variants in the UK. Fluctuation in variant expression from 6.9 to 15.2% of total Hb on high performance liquid chromatography (HPLC) would pose a diagnostic dilemma in routine laboratories. Focusing on the variant expression, the median of Hb Manitoba was around 11.5% of total Hb in three cases, apparently with normal hemoglobin (Hb), and normal red blood cell (RBC) indices. Two cases showed a higher expression (13.9 and 15.2%) and five cases showed a lower expression (6.9-9.9%). The common α-thalassemia (α-thal) -α (rightward) deletion coexisted with one case of increased Hb Manitoba expression. Iron (or other nutrient) deficiency was likely the cause of decreased Hb Manitoba percentage in this study. The α73(EF2)Val→Val (α2) (: c.222G>T) polymorphism is published for the first time and coexisted with two cases. The Cap +14 (C>G) (: c.-24C>G) polymorphism coexisted with another case in a heterozygous state. In conclusion, the fluctuation in variant expression can cause a diagnostic dilemma, especially in routine laboratories. Screening for the common -α deletion and iron deficiency is recommended when an α chain variant is suspected.
Hb 曼尼托巴 [α102(G9)Ser→Arg] 是一种罕见的 α 链变体，具有多种族起源。在大多数文献中，杂合状态下的表达约为 10.0-14.2%，其稳定性轻度降低。在这项研究中，在英国对 α 链变体进行广泛研究期间，检测到 12 例 Hb 曼尼托巴 [11 例携带 Hb 曼尼托巴 II（: c.309C>A），1 例携带 Hb 曼尼托巴 IV（: c.307A>C）]。高效液相色谱法（HPLC）上总 Hb 中变体表达从 6.9%波动至 15.2%，这会给常规实验室造成诊断困境。关注变体表达，在三个病例中 Hb 曼尼托巴的中位数约为总 Hb 的 11.5%，显然血红蛋白（Hb）和红细胞（RBC）指数正常。两个病例的表达较高（13.9%和 15.2%），五个病例的表达较低（6.9%-9.9%）。常见的α-地中海贫血（α-thal）-α（右侧）缺失与一个 Hb 曼尼托巴表达增加的病例共同存在。在本研究中，铁（或其他营养素）缺乏可能是导致 Hb 曼尼托巴百分比降低的原因。α73(EF2)Val→Val（α2）（: c.222G>T）多态性为首次发表，并与两个病例共同存在。Cap +14（C>G）（: c.-24C>G）多态性与另一个杂合状态的病例共同存在。总之，变体表达的波动可能会造成诊断困境，尤其是在常规实验室中。当怀疑存在 α 链变体时，建议筛查常见的-α 缺失和缺铁。
