Institute of Transfusion Medicine and Immunology, Medical Faculty Mannheim, Heidelberg University; German Red Cross Blood Service Baden-Württemberg - Hessen, Mannheim, Magdeburg, Germany.
Institute of Transfusion Medicine and Immunohematology, Otto-von-Guericke University Hospital, Magdeburg, Germany.
Transfus Med Hemother. 2013 Dec;40(6):454-8. doi: 10.1159/000356378. Epub 2013 Oct 27.
Discrepant results in antigen and reverse ABO blood typing are often caused by a variant ABO gene. Molecular analysis can help to characterize such variants. Here, we describe the identification of a novel ABO gene variant in a patient with aberrant ABO phenotype and discrepant genotyping results.
A patient with discrepant results in automated forward and reverse ABO phenotyping was further investigated by serological (gel and tube technique) and molecular (commercial and inhouse PCR-SSP, DNA sequencing) methods. A PCR-SSP system was established to screen the novel mutation in 1,820 blood donors.
Standard serological tests confirmed blood group O, however, only anti-B isoagglutinins were present. A monoclonal anti-AB antibody detected very weak agglutination in gel technique. Standard ABO genotyping using PCR-SSP led to discrepant results (O(1)/O(1) or O(1)/A) depending on the test system used. ABO exon re-sequencing identified a novel missense mutation in exon 6 at position 248A>G (Asp83Gly) in the binding region of PCR-SSP primers for the detection of 261G alleles. Blood donors with regular ABO blood groups were all negative for the 248G allele designated Aw34.
The novel ABO gene variant Aw34 is associated with very weak A antigen expression and absent anti-A isoagglutinins. The mutation is located in exon 6 close to the O(1)-specific 261G deletion in the binding region of PCR-SSP primers. Presumably, depending on the primer concentration used in commercial ABO genotyping kits, the mutation could lead to a false-negative reaction.
抗原和反向 ABO 血型定型不一致的结果通常是由变异的 ABO 基因引起的。分子分析有助于对这些变体进行特征描述。在此，我们描述了一名具有异常 ABO 表型和不一致基因分型结果的患者中新型 ABO 基因变体的鉴定。
通过血清学（凝胶和试管技术）和分子（商业和内部 PCR-SSP、DNA 测序）方法进一步研究了在自动正向和反向 ABO 表型不一致的患者。建立了 PCR-SSP 系统来筛选 1820 名献血者中的新型突变。
标准血清学测试证实血型为 O，但只存在抗-B 同种抗体。单克隆抗-AB 抗体在凝胶技术中仅检测到微弱的凝集。使用 PCR-SSP 进行标准 ABO 基因分型导致不一致的结果（O(1)/O(1) 或 O(1)/A），具体取决于使用的测试系统。ABO 外显子重新测序在结合 PCR-SSP 引物用于检测 261G 等位基因的位置 248A>G（天冬氨酸 83 甘氨酸）的第 6 外显子中发现了一个新的错义突变。具有常规 ABO 血型的献血者均为 Aw34 指定的 248G 等位基因阴性。
新型 ABO 基因变体 Aw34 与非常弱的 A 抗原表达和不存在抗-A 同种抗体相关。该突变位于 6 号外显子，靠近 PCR-SSP 引物结合区域中的 O(1)-特异性 261G 缺失。据推测，由于商业 ABO 基因分型试剂盒中使用的引物浓度不同，该突变可能导致假阴性反应。
